Production of RNA by yeasts with recombinant pseudo-viral particles (2024)

The text file named New SEQ, created on Jun. 14, 2023, and sized 81,714 bytes, which contains sequence ID listings, is herein expressly incorporated by reference.

The application relates to the production of RNA of interest, more particularly messenger RNA (mRNA) of interest or long non-coding RNA (lncRNA) of interest, by recombinant yeasts, more particularly by yeasts with recombinant pseudo-viral particles.

The application concerns these yeasts, as well as the pseudo-viral particles produced thereof.

The application also relates to means for their production, including nucleic acid vectors and kits, as well as medical applications, more particularly vaccine, anti-tumor, anti-infectious and pro-regenerative.

Different methods of producing RNA are known in the art. These methods comprise in vitro synthesis methods that use in particular RNA polymerases.

The production of RNA, in particular mRNA, which are competent for the translation into proteins in mammalian cells, poses the particular problem of post-transcriptional modifications such as the presence of a polyA tail at the 3′ end, a 7-methylguanosine (m7G) cap at the 5′ end, or even certain methylations of adenines and cytosines.

In vitro synthesis methods of the prior art, for example, propose placing cap analogs in the transcriptional mixture, such as m7G5′ppp5′G. In order to stimulate the incorporation of the dinucleotide at the beginning of the chain, the in vitro synthesis methods of the prior art also propose to reduce the concentration of guanosine triphosphate (GTP) in the transcriptional mixture relative to the other nucleoside triphosphates (NTPs), which decreases transcription efficiency. In addition, the cap analog can then be incorporated in both orientations resulting in 50% poorly capped RNA. These methods of in vitro synthesis of RNA are therefore not very effective.

Other in vitro synthesis methods propose to use a chimeric enzyme comprising the catalytic domains of an RNA triphosphatase, a guanylyltransferase, an N7-guanine methyltransferase, and a DNA-dependent RNA polymerase (cf. for example, WO 2011/128444 in the name of EUKARYS). These in vitro RNA synthesis methods nevertheless remain expensive.

RNA recombinant production methods have been further developed. For example, one method proposes using the machinery of the mitochondria, to make it an RNA production and storage unit (see for example WO 2010/084371 in the name of MITOPROD). The RNA thus produced do not, however, have a cap at the 5′ end, which limits their medical applications.

The application provides means for producing RNA that do not have all the drawbacks of the prior art.

The application relates to the production of RNA, more particularly messenger RNA (mRNA) or long non-coding RNA (lncRNA), by recombinant yeasts, more particularly by yeasts with recombinant pseudo-viral particles. Yeasts have been genetically engineered to produce recombinant virus-like particles that contain this RNA, and do not retro-transcribe this RNA or retro-integrate it into their genome.

The RNA thus produced can advantageously have a polyA tail at the 3′ end and a 7-methylguanosine (m7G) cap at the 5′ end. They may therefore be competent for possible translation into mammalian cells. In addition, RNA can be produced in relatively large amounts.

The demand concerns these yeasts, as well as the pseudo-viral particles that they produce.

The application also relates to means for their production, including nucleic acid vectors and kits, as well as medical applications, more particularly vaccine, anti-tumor and pro-regenerative.

This RNA fragment is not intended to be translated into protein in yeast: it serves as an addressing sequence, which guides the RNA (of interest) to the Gag protein, thereby forming a complex between this RNA and Gag protein. This complex takes the form of a particle, in this case a recombinant pseudo-viral particle, which is formed by the polymerization of the Gag protein, and in which the RNA is encapsulated.

The yeast Ty retrotransposon elements used do not comprise the Ty reverse transcription means. More particularly, they do not comprise the integrase means of Ty, or more generally the precursor protein means Pol of Ty.

Some of the figures in the application are in color. The application as filed contains the color version of these figures, which can therefore be viewed by inspection of the application file as filed.

FIG. 1A illustrates the expression of Gag protein (Ty1) in yeasts Saccharomyces cerevisae and Saccharomyces paradoxus. Gag protein expression analysis was performed by Western anti-Gag transfer (49 kDa) on cell lysate samples. Unlike S. cerevisiae, S. paradoxus lacks Ty1 retrotransposon.

FIG. 2A illustrates the confocal fluorescence microscopy analyzes of eGFP expression and Gag-eGFP fusion protein in yeast S. paradoxus. eGFP=Enriched Green Fluorescent Protein; bright field=transmitted light exposure; Ex. 488 nm=exposure at 488 nm wavelength.

FIG. 2C illustrates the flow cytometric analysis of the expression of T-bodies eGFP (Gag-eGFP fusion protein) in the transcriptional mutant of S. paradoxus ΔSrb2 yeast after an 8 hours treatment at the tunicamycin (TUNI). T-bodies expression is under the control of a galactose inducible promoter. CTRL=control; −TUNI=without tunicamycin; +TUNI=with tunicamycin.

FIG. 4 illustrates the transmission electron microscopy image of T-bodies following the protein extraction by two different techniques (left: the pellet obtained by the method of lysis by the beads, on the right the pellet obtained by the method of sonication). The samples were stained with 2% uranyl acetate.

FIG. 5A illustrates the confocal fluorescence microscopy observation of T-bodies by immunofluorescence (anti-Ty1/GAG antibody) in the S. paradoxus ΔSrb2 yeast expressing the Gag protein, the 6His-Gag fusion protein, Gag-6His, 6His-Gag-6His. Bright field=transmitted light exposure; λ488 nm=exposure at a wavelength of 488 nm.

FIG. 5B illustrates the detection of the expression of the Gag protein by western blot (anti-Ty1/Gag antibody) in S. paradoxus ΔSrb2 yeast expressing the Gag protein, the 6His-Gag fusion protein, Gag-6His, 6His-Gag-6His. YAM13 ΔSrb2=S. paradoxus YAM13 yeast strain deleted for the Srb2 gene.

FIG. 5C illustrates western blot analysis (anti-Ty1/GAG antibody) of fractions eluted with imidazole increasing concentration buffers (100 mM, 200 mM, 400 mM, 800 mM). These fractions correspond to the T-bodies extracted from yeast strains expressing Gag, 6His-Gag and Gag-6His and then purified on a column loaded with nickel.

FIG. 8 illustrates the mass spectrometric study of the chemical changes present at the level of messenger RNA bioproduced. This technique is based on mass spectrometry (LC-MS) analysis of the fragments obtained after complete RNase T1 hydrolysis of the RNA studied. The bars of black histograms (RNA before «pull out») correspond to the average of 2 samples of RNAs extracted from T-bodies resulting from mechanical lysis. The white histogram bars (RNA after «pull out») correspond to the average of 2 samples of RNAs extracted from T-bodies resulting from a mechanical lysis followed by a «pull out» protocol allowing the exclusive purification of the RNA of interest.

D=dihydrouridine; Psi=pseudouridine; m5U=5-methyluridine; m5C=5-methylcytidine; m2G=N2-methylguanosine; mlA=1-methyladenosine; m1G=1-methylguanosine; Gm=2′-O-methylguanosine; m22G=N2, N2-dimethylguanosine; m7G=7-methylguanosine; Am=2′-O-methyladenosine; Cm=2′-O-methylcytidine; mcm5s2U=5-methoxycarbonylmethyl-2-thiouridine; m3C=3-methylcytidine and m6A=N6-methyladenosine.

The application describes the objects defined in the claims as filed, the objects described below and the objects illustrated in part «examples».

The application relates in particular to a method for producing (recombinant) RNA, to a method for producing a pharmaceutical composition, and to products that may be used or produced in these methodes, in particular nucleic acids (more particularly nucleic acid vectors, such as plasmids), kits, recombinant bacteria cells, recombinant yeast cells, as well as recombinant pseudo-viral complexes, granules or particles.

The application implements some Ty retrotransposon elements of yeast (but not all elements of this retrotransposon). It implements in particular yeast genetic modification means, which derive from the Gag protein of a yeast Ty retrotransposon and the RNA of this protein. However, the application does not implement the reverse transcript Ty reverse transcription means.

The application makes it possible in particular to produce RNAs, especially messenger RNAs (mRNAs) or long non-coding RNAs (lncRNAs), which have a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end, or even methylation of adenine and/or cytosine and/or pseudouridine residue (s). The means of demand also make it possible to produce these RNAs in a relatively large amount, and at a reduced cost. The means of the request therefore make it possible to clinically access the medical applications of RNAs (such as mRNA and lncRNA), particularly in the field of immunotherapy and gene therapy.

This RNA advantageously comprises an addressing sequence, namely a sequence which enables it to be addressed to a Gag protein of a yeast Ty retrotransposon. In addition to the addressing sequence, the RNA may in particular comprise at least one RNA of interest, such as at least one prokaryotic RNA (especially bacteria), viruses (especially Zika or Influenza), or eukaryotic, in particular of eukaryote other than yeast (for example of human), and/or at least one artificial or non-natural RNA (for example an RNA whose translation is a sequence which comprises various epitopes of viruses and/or bacteria), This RNA can advantageously be an mRNA or a lncRNA, more particularly an mRNA.

This RNA can be a yeast-heterologous RNA that produces it, or even a heterologous yeast in general.

The genetic modifications that have been made to the yeast cells to produce this RNA comprise in particular the transfer into these yeast cells (in particular by transfection or transformation) of a nucleic acid construct which codes for a Gag protein of a yeast Ty retrotransposon.

RNA (more particularly mRNA or lncRNA) is produced by yeast cells with a Gag protein of a yeast Ty retrotransposon, in the form of a structure that can be described as complex, granule or pseudo-viral particle.

One or more different RNAs can thus be produced.

The, or at least one, of the transferred nucleic acid construct (s) may be integrated into the genome, or may not be integrated into the genome but may be present in the nucleus or cytoplasm, for example as an episome.

For example, a nucleic acid construct that encodes the yeast Ty retrotransposon Gag protein can be integrated into the yeast genome, while the nucleic acid construct of which the RNA transcript comprises said addressing sequence and/or the RNA sequence of interest, may not be integrated into the chromosome (but be present in the nucleus and/or the cytoplasm, especially in the form of an episome).

The term prokaryotic is understood according to its usual meaning in the field. It relates more particularly to a bacteria, especially a bacteria with potential infectious and/or pathogenic for the human species.

The term virus is understood according to its usual meaning in the field. It relates more particularly to a virus, in particular a virus with potential infectious and/or pathogenic for the human species, in particular Zika or Influenza.

The term eukaryotic is understood according to its usual meaning in the field. When it relates to the RNA, the mRNA or the mRNA of the application, it relates more particularly to a eukaryotic other than yeast, more particularly a multicellular eukaryote such as a mammal (more particularly a human or a non-human mammal), more particularly a human.

The term Ty is understood according to its usual meaning in the field. It relates more particularly to a Ty1, Ty2, Ty3, Ty4 or Ty5 retrotransposon, more particularly a Ty1, Ty2 or Ty3 retrotransposon, more particularly a Ty1 retrotransposon.

The term yeast is understood according to its usual meaning in the field.

It relates more particularly to a yeast of the genus Saccharomyces or the genus Pichia, more particularly of the genus Saccharomyces.

Among the yeasts of the genus Saccharomyces, the species paradoxus and cerevisiae, in particular the species paradoxus, are more particularly targeted.

Among the yeasts of the genus Pichia, the species P. pastoris is particularly targeted. An example of S. paradoxus strain is the strain that is accessible from ATCC under the number 76528™. ATCC® is the American Type Culture Collection (10801 University Blvd.; Manassas, Virginia 20110-2209; USA.).

An example of S. cerevisiae strain is strain YAM510, which does not contain functional Ty1 retrotransposon, and which has been described in Rothstein et al. 1983 and Thomas et al. 1989.

Alternatively or additionally, the yeast can be devoid of Ty2, Ty3, Ty4 and Ty5 retrotransposon, or (although it is naturally provided with it) has been genetically modified so as not to produce a T retrosome which would be encoded by a Ty2, Ty3, Ty4 or Ty5 retrotransposon.

Advantageously, the yeast is a yeast which is (naturally) devoid of retro-transposon Ty, or is a yeast which is naturally provided in one or more retro-transposon Ty but whose sequence of these or these retro-transposons Ty has been genetically modified so as not to produce a T-retrosome.

Advantageously, the yeast is devoid of retro-transposon Ty, or has been genetically modified so as not to produce a T-retrosome.

The fact of using a yeast which is devoid of this (these) retrotransposon(s) Ty, or which does not produce this (these) Ty retrosome (s), makes it possible in particular to limit or avoid that the RNA (mRNA or lncRNA) produced is retro-transposed (into cDNA) (and thus to limit or avoid the «loss» of mRNA or lncRNA by unwanted cDNA backtranscription).

The yeast Saccharomyces paradoxus is an example of yeast which is naturally devoid of Ty retrotransposon, in particular Ty1 retrotransposon. S. paradoxus can therefore be directly implemented for the transfer of nucleic acids from i. and/or ii. The yeast Pichia pastoris is a yeast which is naturally free of Ty retrotransposon, and can therefore be directly used for transferring nucleic acids from i. and/or ii.

The yeast Saccharomyces cerevisiae is an example of yeast which is naturally provided with Ty retrotransposons, in particular a Ty1 retrotransposon. It must therefore be genetically modified so as not to produce a Ty retrosome, in particular a Ty1 retrosome.

A genetic modification that makes it possible not to produce Ty retrosome (s) may, for example, comprise the deletion (in the chromosome of the yeast) of the expression promoter of the Ty retrotransposon (s), and/or a mutation of this chromosome (by deletion and/or replacement and/or insertion of one or more nucleotides) interrupting at least one of the open reading frames of the Ty retrotransposon (s).

The nucleic acid of i. may for example be in the form of episomes that replicate autonomously or be integrated with the chromosomes of the yeast.

The nucleic acid of ii. may for example be in the form of episomes that replicate autonomously or be integrated with the chromosomes of the yeast.

The nucleic acid of i. code the expression of the Gag protein which will form the pseudo-viral particle, or be comprised in the protein polymer which forms this particle (cf. FIGS. 7A, 7B and 7C).

The nucleic acid of ii. «encodes» the transcription of the RNA which contains the RNA of interest to be produced, linked to an addressing RNA sequence which guides this RNA of interest towards the Gag protein of the pseudo-viral particle in formation (cf. FIGS. 7A, 7B and 7C).

The combination of nucleic acids of i. and ii. thus produces a pseudo-viral particle containing the RNA of interest (for example an mRNA or lncRNA) (cf. FIGS. 7A, 7B and 7C).

The nucleic acid of ii. (or each of the sequences it contains) is therefore intended to be transcribed into RNA in yeast, but it is not particularly intended to be translated into protein. The nucleic acid of ii. (or each of the sequences it contains) can therefore be a sequence which, in a yeast, cannot be translated into protein (or polypeptide). On the other hand, the RNA thus transcribed and produced in the yeast cell may be an RNA which encodes the expression of a protein (or a polypeptide) in a mammalian cell (for example an RNA which encodes expression of one or more antigens in a mammalian cell).

For example, the Gag protein may in particular be a Gag protein of another yeast retrotransposon other than the Ty1 retrotransposon of S. cerevisiae (retrotransposon of S. cerevisiae other than Ty1, and/or retrotransposon of yeast other than S. cerevisiae, for example yeast Ty1 retrotransposon other than S. cerevisiae), the sequence of which is at least 90% identical to the sequence of SEQ ID NO: 3.

The Gag protein of a yeast Ty retrotransposon may thus be in particular a protein whose sequence is the sequence of SEQ ID NO: 3 or a sequence which is at least 90% (more particularly at least 95%) identical to the sequence of SEQ ID NO: 3, and which is a Gag protein of a yeast Ty1, Ty2 or Ty3 retrotransposon.

In the second nucleotide sequence, the “b. sequence” has the particular function of addressing the “a. sequence” (in this case, the RNA of interest) to the Ty retrotransposon Gag protein which is produced by the first nucleotide sequence, more particularly to address it to a protein polymer containing this Gag protein which is synthesized in the yeast cell genetically modified.

The second nucleotide sequence is intended to be transcribed into RNA, but it is not particularly intended to be translated into protein in yeast. It is indeed in RNA form that it carries out its addressing or guide function. The second nucleotide sequence may therefore be advantageously devoid of a reading frame whose first codon would be the start codon of translation [start] (ATG). Advantageously, the addressing sequence or “b. sequence” comprises a fragment of the RNA sequence whose translation into amino acids is the sequence of said Gag protein of a yeast Ty retrotransposon.

This fragment may comprise a fragment of at least 150 nucleotides, more particularly at least 200 nucleotides, more particularly at least 250 nucleotides, more particularly at least 300 nucleotides, more particularly at least 350 nucleotides, more particularly at least 398 nucleotides, more particularly at least 500 nucleotides, more particularly at least 1000 nucleotides, more particularly at least 1078 nucleotides. In what follows, the expression «at least 150 nucleotides» explicitly comprises each of the upper thresholds that are above indicated (at least 200 nucleotides, etc.).

Advantageously, the “b. sequence” does not comprise the [start] translation start codon (AUG) of the RNA sequence of said Gag protein of yeast Ty retrotransposon. In the RNA sequence whose translation would be the sequence of SEQ ID NO: 3 (S. cerevisiae Ty1 Gag protein), this start codon is the AUG codon which is the transcript of the ATG codon at the 1-3 positions of the sequence SEQ ID NO: 2. This translation start codon may be deleted, or may be mutated to a codon other than «start», for example a stop codon (UAA, UAG or AGA).

More generally, the RNA fragment that is comprised in said b. addressing sequence and which is a fragment of the RNA sequence whose translation into amino acids would be the sequence of said Gag protein of a yeast Ty retrotransposon, does not advantageously comprise a reading frame whose first codon would be a translation start codon (AUG). More generally, this RNA fragment does not comprise a reading frame which, in a yeast, would be an open reading frame (this sequence is intended to be transcribed into RNA in yeast, but it is not particularly intended to be translated into protein).

More generally, the b. addressing sequence advantageously does not comprise a reading frame whose first codon would be the translation start codon (AUG). More generally, it does not comprise a reading frame which, in a yeast, would be an open reading frame (this sequence is intended to be transcribed into RNA in yeast, but it is not particularly intended to be translated into protein).

Complementarily to the absence of this translation start codon, the “b. sequence” may comprise one or more stop codons (UAA, UAG, or AGA) in at least one, if not all, of the three reading frames.

More generally, the second nucleotide sequence advantageously does not comprise a reading frame whose first codon would be the translation start codon [ATG], more generally it does not comprise a reading frame which, in a yeast, would be an open frame of reading (this sequence is intended to be transcribed into RNA in yeast, but it is not particularly intended to be translated into protein).

Advantageously, the nucleic acid of ii. does not comprise a DNA sequence that encodes a complete RNA sequence of said Gag protein of a yeast Ty retrotransposon.

The term «encode» (and its grammatical equivalents) is understood in its usual meaning in the field. This term is applied both to the expression of a DNA sequence in protein, that is to say its transcription and its translation (DNA codons transcribed in RNA codons, then translated into amino acids according to the universal genetic code, and taking due account of the degeneracy of this code).

For simplicity, this term can here also be applied to the (simple) transcription of a DNA sequence in RNA sequence (for example, nucleotides A, T, G and C transcribed in nucleotides A, U, G and C, respectively), or the (simple) translation of an RNA sequence into amino acids (according to the universal genetic code, and with due regard to the degeneracy of this code). The expression «code the expression» or «code transcription» may be understood by the person skilled in the art as implying the presence in the DNA sequence of sequence (s) allowing to induce, in particular to initiate, transcription, by example the presence of the sequence of (at least) a promoter.

The first nucleotide sequence thus advantageously comprises a DNA sequence (or cDNA, or gDNA) which is the coding sequence [CDS] of the open reading frame of the Gag protein of a yeast Ty retrotransposon, under the control of a promoter for the expression of this open framework.

The DNA sequence of the second nucleotide sequence advantageously comprises a DNA sequence which is the retro-transcript of an RNA sequence which comprises the RNA (mRNA or lncRNA) of interest, under the control of a promoter for the transcription of this DNA (but preferably without comprising reading frame, which, in a yeast, would be an open reading frame).

Advantageously, the nucleic acid of i. and the nucleic acid of ii. are nucleic acid vectors, more particularly nucleic acid vectors adapted to the transfer of nucleic acids into yeast cells, for example suitable for transfection or transformation of these yeast cells. Nucleic acid i. and the nucleic acid of ii. can (each independently of each other) be or not be integrative (that is to say, be or not be intended to integrate with the chromosome of the cell that receives them in transfer).

The term «nucleic acid vector» is intended in accordance with its usual meaning in the art. It relates more particularly to a plasmid, more particularly a replicative plasmid or an episomal plasmid. Thus, the nucleic acid of i. and the nucleic acid of ii. may each independently of one another be plasmids, especially episomal plasmids or replicative plasmids.

The nucleic acid of i. may for example be a nucleic acid vector, in particular a plasmid (episomal or non-integrative), which comprises the first insert nucleotide sequence for its transcription and its translation into a yeast cell.

The nucleic acid of ii. may for example be a nucleic acid vector, in particular a plasmid (episomal or non-integrative), which comprises the second insert nucleotide sequence for its transcription in a yeast cell. For example, the nucleic acid of i. is an episomal plasmid, while the nucleic acid of ii. is a non-integrative plasmid, more particularly a replicative vector.

The nucleic acid of i. and the nucleic acid of ii. can be a single molecule, or be two distinct or separate molecules. For example, the nucleic acid of i. and the nucleic acid of ii. can be a single nucleic acid vector, in particular a single plasmid, or be two distinct or distinct nucleic acid vectors, in particular two distinct or separate plasmids.

Advantageously, the nucleic acid of i. and the nucleic acid of ii. are each (independently of each other) present in multiple copies. Advantageously, the number of copies of the nucleic acid of ii. is greater (for example 2, 3, 4, 5 or 6 times greater) than the number of copies of the nucleic acid of i. The first nucleotide sequence can be integrated into the yeast genome that has received the nucleic acid of i. in transfer, or not to be integrated.

The second nucleotide sequence can be integrated into the genome of the yeast that has received the nucleic acid of ii. in transfer, or not to be integrated.

For example, the first nucleotide sequence is integrated into the genome of the yeast, and the second nucleotide sequence is not integrated (but is present in the nucleus and/or cytoplasm, for example by being comprised in the nucleic acid of the yeast. ii.).

The nucleic acid of i. and the nucleic acid of ii. thereby encoding the formation, in (the cytoplasm of said) yeast cells, of a pseudo-viral particle which is formed by a protein polymer which comprises the translated Gag protein from the first nucleotide sequence, and which encapsulates said RNA (mRNA or lncRNA) of interest transcribed from the second nucleotide sequence.

In addition to the DNA sequence which encodes the expression of the Gag protein of a yeast Ty retrotransposon, the first nucleotide sequence, the nucleic acid of i, may comprise a DNA sequence which encodes the expression of a marker. for the detection of the Gag protein (e.g., a DNA sequence which encodes a fluorescent label, e.g. a fluorescent marker linked to or fused to a green fluorescent protein (GFP), especially an eGFP) and/or the expression of a label for the purification of the Gag protein (for example, a DNA sequence which encodes a poly-histidine tag and/or the bacteriophage MS2 sequence, fused the Gag protein) (cf. FIGS. 7A, 7B and 7C).

In addition to the addressing sequence, the second nucleotide sequence advantageously comprises an RNA (mRNA or lncRNA) of interest linked to this addressing sequence. The second nucleotide sequence may further comprise a DNA tag purification sequence, such as one or more (e.g., three) copies of the bacteriophage MS2 sequence (cf. FIGS. 7A, 7B and 7C).

The nucleic acid of i. can be integrated into the genome of the yeast, or not be integrated in the genome but be present in the nucleus and/or the cytoplasm of the yeast, for example in the form of an episome.

The nucleic acid of ii. can be integrated in the genome of yeast, or not be integrated into the genome but be present in the nucleus and/or cytoplasm of the yeast.

For example, the nucleic acid of i. can be integrated into the genome of yeast, and the nucleic acid of ii. may not be integrated into the genome but be present in the nucleus and/or cytoplasm of the yeast, for example as an episome.

For example, the nucleic acid of i. and the nucleic acid of ii. can both be integrated into the yeast genome (they can then be one and the same nucleic acid molecule).

Most generally, the nucleic acid of i. and the nucleic acid of ii. are each DNA. Most generally, the first nucleotide sequence and the second nucleotide sequence are each a DNA sequence, more particularly cDNA. The first nucleotide sequence is (or comprises) a DNA sequence that encodes the expression of the Gag protein of a yeast Ty retrotransposon. It therefore comprises, or is, an open reading frame that encodes the sequence of this protein.

Most generally, in the second nucleotide sequence, the bond between the sequence a. said RNA (mRNA or lncRNA) of interest, and the b. addressing sequence, is a covalent bond, or a direct bond, or a covalent and direct bond. This binding may in particular be at the 5′ or 3′ end of the sequence of the RNA of interest. For example, the b. addressing sequence is covalently linked to the 5′ end of the sequence of the RNA of interest. For example, the b. addressing sequence is linked directly and covalently to the 3′ end of the sequence of the RNA of interest.

The first nucleotide sequence advantageously contains (at least) a promoter for its expression, or for the transcription and translation of the open reading frame that it contains. The first nucleotide sequence may therefore comprise an open reading frame that encodes the sequence of the Gag protein of a yeast Ty retrotransposon, under the control of a promoter for the transcription and translation of this open reading frame into a yeast cell.

The second nucleotide sequence advantageously contains (at least) a promoter for its transcription, in particular for its transcription in a yeast cell.

The promoter of the first nucleotide sequence may be the same as that of the second nucleotide sequence, or it may be different promoters.

These promoters may each independently of one another be a constitutive promoter or an inducible promoter (e.g., a galactose-inducible promoter).

These promoters can each independently of one another be a strong promoter, that is to say a promoter to which the transcription complex (and in particular the RNA polymerase) can bind to initiate transcription, without which there must necessarily be additional factors (such as the sigma factor). For example, the promoter of the second nucleotide sequence may be a strong promoter.

Advantageously, the promoter of the first nucleotide sequence is a promoter for the expression of this first nucleotide sequence in a eukaryotic cell, more particularly a yeast cell (more particularly, for transcription and translation, in a eukaryotic cell, especially in a yeast cell, of the open reading frame which is contained in this first nucleotide sequence).

Advantageously, the promoter of the second nucleotide sequence is a promoter for the transcription of the second nucleotide sequence in a eukaryotic cell, more particularly a yeast cell.

Any inducible or constitutive promoter that the person skilled in the art considers appropriate may be implemented. Examples of inducible promoters comprise in particular promoters Gal1, Gal10, Tet07, Met.

Examples of constitutive promoters comprise, in particular, the promoters ADH, CYC, PGK1, GPD.

Advantageously, the first nucleotide sequence contains (at least) an origin for its replication, or for the replication of the open reading frame that it contains.

Likewise, the second nucleotide sequence advantageously contains (at least) an origin for its replication.

The origin of replication contained in the first nucleotide sequence is advantageously an origin of replication in prokaryote and eukaryote, more particularly an origin of replication in bacteria and yeast.

Similarly, the origin of replication contained in the second nucleotide sequence is advantageously a prokaryotic and eukaryotic origin of replication, more particularly an origin of replication in bacteria and yeast.

Advantageously, the yeast cells are yeast cells which do not comprise a nucleotide sequence which would allow the retrotransposition of the RNA (mRNA or lncRNA) of interest. One objective here is to limit or avoid the loss of RNA (mRNA or lncRNA) produced by their retro-transcription into cDNA.

Thus, advantageously, the nucleic acid of i. and the nucleic acid of ii. do not comprise a sequence encoding a reverse transcriptase of a yeast Ty retrotransposon, more generally any sequence encoding the expression of a reverse transcriptase.

Alternatively or additionally, the nucleic acid of i. and the nucleic acid of ii. may be devoid of sequence encoding the expression of an integrase of a yeast Ty retrotransposon, more generally any sequence coding the expression of an integrase. In other words, the sequence of the nucleic acid of i. and the sequence of the nucleic acid of ii. may lack an open reading frame, which encodes the integrase of a yeast Ty retrotransposon, or more generally an integrase, and/or they may be devoid of an expression promoter of such an integrase.

The nucleic acid of i. and the nucleic acid of ii. may furthermore be devoid of a sequence encoding the expression of a protease of the yeast Ty retrotransposon, more generally any sequence encoding the expression of a protease. In other words, the sequence of the nucleic acid of i. and the sequence of the nucleic acid of ii. may be devoid of an open reading frame, which encodes the protease of a yeast Ty retrotransposon, or more generally a protease, and/or they may be devoid of an expression promoter of such a protease.

The nucleic acid of i. and the nucleic acid of ii. may therefore be devoid of sequence encoding the expression of the Pol protein of the yeast Ty retrotransposon, more generally any sequence encoding the expression of a Pol protein.

In other words, the sequence of the nucleic acid of i. and the sequence of the nucleic acid of ii. may be devoid of an open reading frame, which encodes the Pol protein of a yeast Ty retrotransposon, or more generally a Pol protein, and/or they may be devoid of an expression promoter of such a Pol protein.

Said RNA (mRNA or lncRNA) of interest may in particular be the yeast strain implemented, or even all yeasts.

Said RNA (mRNA or lncRNA) of interest may comprise at least 120 nucleotides, in particular at least 150 nucleotides, in particular at least 180 nucleotides, in particular at least 210 nucleotides, in particular at least 240 nucleotides, in particular at least 270 nucleotides, in particular at least 2300 nucleotides.

Alternatively or additionally, said RNA (mRNA or lncRNA) to be produced may comprise less than 6000 nucleotides, less than 5800 nucleotides, in particular less than 5000 nucleotides, in particular less than 4000 nucleotides, in particular less than 3000 nucleotides, in particular less than 2000 nucleotides, in particular less than 1800 nucleotides. All combinations of minimum number and maximum number of nucleotides are here explicitly targeted. Said RNA (mRNA or lncRNA) of interest may for example comprise at least 150 nucleotides and less than 2000 nucleotides.

Several different RNAs (mRNA or lncRNA) can be produced in the same yeast recombinant cell. Each of these different RNAs has a second nucleotide sequence of its own (DNA sequence whose RNA transcript comprises the RNA sequence of interest linked to an addressing sequence). Each of these second nucleotide sequences may be comprised or carried on the same nucleic acid molecule of ii, or on separate nucleic acid molecules of ii. The yeast which has been genetically modified to produce the complexes, granules or pseudo-viral (recombinant) particles of the application may advantageously have genetic mutations, in particular chromosomal mutations, which are intended to stimulate or increase the production of these pseudo-viral particles.

The yeast genes may for example be one or more genes among the Rpb1, Spt21, Srb2 and Srb5 genes.

For example, the Rpb1 gene may comprise a codon substitution that confers the amino acid mutation C67Y, C70Y or H80Y. For example, the Rpb1 gene of the strain may be replaced by the Rpb1 gene of another yeast strain, in particular another yeast strain which belongs to the same genus of yeast, and which carries at least one of these substitutions of codons. For example, the Rpb1 gene of S. paradoxus can be replaced by the Rpb1 gene of S. cerevisiae, into which one or more of the codon mutations that confer the amino acid mutations C67Y, C70Y and H80Y have been introduced.

For example, one or more of the Spt21, Srb2 and Srb5 genes may be (at least partially) deleted [ΔSpt21, ΔSrb2 and ΔSrb5].

Alternatively or additionally to genetic mutations, including chromosomal mutations, which are intended to stimulate or increase the production of these pseudo-viral particles, one or more products may be used to stimulate or increase this production. This or these products may in particular be present in the transfection or culture medium in which the yeast is placed.

Yeast (recombinant) cells which have been genetically modified to comprise nucleic acids of i. and ii. can be placed under conditions allowing the nucleic acid of i. (at the first nucleotide sequence) to express the Gag protein that it encodes, and to the nucleic acid of ii. (at the second nucleotide sequence) to transcribe the AR that it codes. They can in particular be placed on or in a culture medium adapted to the growth or multiplication of yeast (cf. below). If the first nucleotide sequence and/or the second nucleotide sequence carry inducible promoters, this medium may especially comprise any compound or product that would be necessary for the induction of the promoter (s).

The complexes, granules, or virus-like particles produced by the (recombinant) yeast cells are collected, for example by lysis of the cells, in particular by chemical or mechanical lysis (by beads, rather than by sonication), and the RNA contained in these complexes, granules or pseudo-viral particles, and in particular the mRNA or lncRNA thus contained, are purified.

Alternatively, the RNAs contained in these complexes, granules or pseudo-viral (recombinant) particles, and in particular the mRNAs or lncRNAs contained therein, are directly extracted or purified from the yeast cells, without extraction or prior collection of the complexes, granules or pseudo-viral particles that contain them. Large amounts of RNA (mRNA or lncRNA) can thus be produced, for example at least 0.9 gram of RNA (mRNA or lncRNA) per liter of yeast culture.

Advantageously, the RNA, which is present or produced in the complex, granulates, pseudo-viral particle of the application, comprises post-transcriptional modifications that make it competent for translation into mammalian cells.

Advantageously, the complex RNA, granule, pseudo-viral particle of the application can be provided with a polyA tail at the 3′ end.

Advantageously, the complex RNA, granule, pseudo-viral particle of the application can be provided with a cap at the 5′ end, more particularly a cap as known to those skilled in the art, more particularly a cap which comprises a 7-methylguanosine (linked to the mRNA by three phosphates in 5′-5′ configuration). This cap may block the action of exonucleases and may be necessary to stimulate the (future) translation of the RNA of interest (mRNA or lncRNA) into mammalian cells.

Advantageously, the complex RNA, granule, pseudo-viral particle of the application can be methylated, especially at one or more of its adenine and/or cytosine and/or pseudouridine residue(s), especially at one or more of its adenine and/or cytosine residue(s).

Advantageously, the RNA, which is present or produced in the complex, granulates, the pseudo-viral particle of the application, comprises post-transcriptional modifications such as methylation of cytosine and/or adenine and/or pseudouridine residue(s), more particularly of cytosine and/or adenine residue(s) which increase its translational efficiency in mammalian cells.

The means of the application are therefore particularly suitable for the production of RNA (mRNA or lncRNAc) which is intended for administration in a eukaryote, in particular a multicellular eukaryote, in particular a mammal, in particular a human.

Several examples of yeast strains according to the application have been filed with the CNCM (see below).

The application also relates to each of the means implemented or produced by the RNA production method described herein, so that for their use the production of mRNA or lncRNA exhibiting a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or methylation of adenine and/or cytosine and/or pseudouridine residue(s), including adenine and/or cytosine residue(s)).

The application is thus relative to the nucleic acid of i. as described herein.

The application also relates to the nucleic acid of ii. as described herein.

The application is thus related to the association of the nucleic acid of i. and the nucleic acid of ii. as described herein, and their combination for simultaneous, separate or delayed use, more particularly for their simultaneous, separate or delayed use in the transfection or transformation of yeast cells, more particularly yeast as described.

More particularly, the application relates to a kit which comprises a nucleic acid i. and/or, preferably and, a nucleic acid ii. as here described. This kit is especially adapted to the recombinant production of RNA, in particular mRNA or lncRNA, as described here.

Advantageously, the kit does not comprise a protein or nucleic acid allowing retrotransposition of the mRNA or lncRNA to produce, more particularly its retrotransposition in a yeast cell.

Advantageously, the kit does not comprise a reverse transcriptase of a yeast Ty retrotransposon, or nucleic acid encoding such a reverse transcriptase.

Alternatively or additionally, the kit does not comprise an integrase of a yeast Ty retrotransposon, or nucleic acid encoding such an integrase.

Advantageously, the kit does not comprise a protease of a yeast Ty retrotransposon, or nucleic acid encoding such a protease.

More generally, the kit may not comprise a reverse transcriptase or nucleic acid encoding a reverse transcriptase.

More generally, the kit may not comprise an integrase or nucleic acid encoding an integrase.

More generally, the kit may not comprise a protease or nucleic acid encoding a protease.

The kit may not comprise yeast retrotransposon reverse transcriptase, or nucleic acid encoding such a reverse transcriptase, or nucleic acid comprising a sequence encoding such a reverse transcriptase.

The yeast cell(s) of the kit may advantageously not comprise a protein which would allow the retrotransposition of the RNA (mRNA or lncRNA) to be produced (reverse transcriptase, in particular), or of nucleic acid which would code such a protein.

Advantageously, the yeast cell(s) of the kit do not comprise a reverse transcriptase of a yeast Ty retrotransposon, or nucleic acid encoding such a reverse transcriptase.

Alternatively or additionally, the yeast cell(s) of the kit do not comprise an integrase of the yeast Ty retrotransposon or nucleic acid encoding such an integrase.

Advantageously, the yeast cell or cells of the kit do not comprise a protease of a yeast Ty retrotransposon, or nucleic acid encoding such a protease.

More generally, the yeast cell (s) of the kit may not comprise a reverse transcriptase or nucleic acid encoding a reverse transcriptase.

More generally, the yeast cell (s) of the kit may not comprise an integrase or nucleic acid encoding an integrase.

More generally, the yeast cell (s) of the kit may not comprise a protease or nucleic acid encoding a protease.

Of course, the yeast of the kit may comprise one or more copies of at least one of the nucleic acid of i. and the nucleic acid of ii.

The kit may further comprise a leaflet containing instructions for its use in the transfection or transformation of yeast cells, and/or for its use in the (recombinant) production of RNA, more particularly mRNA or lncRNA, such as described here, especially for this production in yeast cells.

The kit may in particular comprise a leaflet containing instructions for genetically modifying cells of a yeast, in particular yeast as described here (or, where appropriate, as contained in the kit), these genetic modifications comprising the transfection or transformation of these yeast cells by nucleic acids i. and ii. of the kit.

The kit may advantageously be used for the production of mRNA or lncRNA exhibiting a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of adenine and/or cytosine and/or pseudouridine residue(s), especially adenine and/or cytosine residues(s)).

The application also relates to a bacteria cell that has been genetically engineered to comprise the nucleic acid of i. and/or, preferably, and the nucleic acid of ii. as described herein, in particular to comprise them in its cytoplasm.

The application also relates to a plurality of such bacteria cells, and in particular to a strain of bacteria whose cells comprise or are such cells. The bacteria may for example be Escherichia, especially E. coli, for example the bacteria E. coli DH5a, which is accessible from the ATCC under the number 67877™. The bacteria cell or cells may advantageously be used to amplify the nucleic acids of i. and/or ii, for example before transferring them to a yeast cell.

The application also relates to a culture medium for microorganisms, in particular to an artificial medium for culturing bacteria, which comprises at least one bacteria cell of the application or at least one strain of bacteria of the application.

This medium may for example be in liquid or solid form.

The composition of this culture medium may be that of a culture medium suitable for bacteria growth or multiplication. In particular, it comprises one or more elements among tryptone, yeast extract and NaCl, more particularly at least yeast extract, more particularly at least yeast extract and tryptone. For example, the composition of this culture medium may in particular be or comprise that of a SOB medium (Super Optimal Broth), a SOC medium (Super Optimal Broth with Catabolite Repression), or an LB medium (Lysogeny Broth). This type of culture medium composition is well known to those skilled in the art. A SOB medium may for example comprise tryptone and yeast extract, for example: 2% w/v tryptone, 0.5% w/v yeast extract, 8.56 to 10 mM NaCl, 2.5 mM KCl 10 mM MgCl₂, 10 mM MgSO₄, H₂O qsp 1000 mL.

A SOC medium may differ from a SOB medium only by the addition of a sugar, for example glucose, for example 20 mM glucose.

An LB medium may for example comprise tryptone, yeast extract and NaCl.

The culture medium may advantageously be used for the production of mRNA or lncRNA having a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of adenine and/or cytosine and/or pseudouridine, especially adenine and/or cytosine residue(s)).

The application also relates to a yeast cell that has been genetically modified to comprise the nucleic acid of i. and/or, preferably, and the nucleic acid of ii. as described herein, especially to comprise these nucleic acids in its nucleus (including its chromosomes) and/or its cytoplasm.

For example, the yeast cell may comprise the first nucleotide sequence, more particularly the first nucleotide sequence integrated into its chromosomes. This yeast cell may further comprise the nucleic acid of i. in its nucleus and/or cytoplasm, in non-integrated form to its chromosomes, for example in the form of a replicative plasmid.

The yeast cell may advantageously not comprise a protein which would allow the retrotransposition of the mRNA or lncRNA to be produced (reverse transcriptase, in particular), or nucleic acid which would encode such a protein.

Advantageously, the yeast cell does not comprise a reverse transcriptase of a yeast Ty retrotransposon, or nucleic acid encoding such a reverse transcriptase.

Alternatively or additionally, the yeast cell does not comprise an integrase of a yeast Ty retrotransposon or nucleic acid encoding such an integrase.

Advantageously, the yeast cell does not comprise a protease of a yeast Ty retrotransposon, or nucleic acid encoding such a protease.

More generally, the yeast cell may not comprise a reverse transcriptase or nucleic acid encoding a reverse transcriptase.

More generally, the yeast cell may not comprise an integrase or nucleic acid encoding an integrase. More generally, the yeast cell may not comprise a protease or nucleic acid encoding a protease.

The yeast cell (s) may advantageously be used for the production of mRNA or lncRNA having a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of cytosine and/or adenine and/or pseudouridine residue(s), more particularly cytosine and/or adenine residue(s)).

The application also relates to a plurality of such yeast cells, and in particular to a yeast strain whose cells comprise or are such cells. The yeast cell or strain of the application is especially adapted to the (recombinant) production of RNA, especially RNA heterologous to this yeast, more particularly mRNA or lncRNA heterologous to this yeast.

A yeast strain of the application can in particular be the strain I-5171 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TB16»). This yeast is a strain of S. paradoxus, whose Rpb1 gene has been replaced by a mutated version of the S. cerevisiae Rpb1 gene (ie a C67Y version of the S. cerevisiae Rpb1 gene), and in which a nucleic acid of i. has been transferred. This nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA].

A yeast strain of the application may in particular be the strain I-5172 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TB17»). This yeast is a strain of S. paradoxus, whose Rpb1 gene has been replaced by a mutated version of the S. cerevisiae Rpb1 gene (ie a C70Y version of the S. cerevisiae Rpb1 gene), and in which a nucleic acid of i. has been transferred. This nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA].

A yeast strain of the application may in particular be the strain 1-5173 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TB18»). This yeast is a strain of S. paradoxus, whose Rpb1 gene has been replaced by a mutated version of the S. cerevisiae Rpb1 gene (namely an H80Y version of the S. cerevisiae Rpb1 gene), and in which a nucleic acid of i. has been transferred. This nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA].

A yeast strain of the application may in particular be the strain I-5174 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TB21»). This yeast is a strain of S. paradoxus, whose Srb2 gene has been deleted, whose Rpb1 gene has been replaced by a mutated version of the S. cerevisiae Rpb1 gene (namely an H80Y version of the S. cerevisiae Rpb1 gene), and in which a nucleic acid of i. has been transferred. This nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA].

A yeast strain of the application may in particular be the strain I-5175 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TB32»). This yeast is a strain of S. paradoxus, whose Srb2 gene has been deleted, and in which a nucleic acid of i. has been transferred. This nucleic acid of i. is integrated into the genome of yeast, and comprises a sequence encoding the Gag-eGFP-6His-3MS2 fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27; 6His of SEQ ID NO: 6; 3MS2=3 copies of the bacteriophage MS2 sequence, as a purification tag) under the influence of a galactose (Gal) promoter [selective medium URA].

A yeast strain of the application may in particular be the strain I-5176 which was deposited with the CNCM under the Budapest Treaty on Feb. 24, 2017 (strain «TBScl»).

This yeast is a strain of S. cerevisiae, which is virgin of Ty elements (TyO), and which has been transformed by an episomal plasmid containing a nucleic acid of i., In this case a nucleic acid allowing the expression of a Gag-eGFP fusion protein (Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence of a galactose (Gal) promoter [selective medium URA].

The CNCM is the National Collection of Culture of Microorganisms (Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France).

A yeast strain of the application may also be one of I-5171 to I-5176, wherein a nucleic acid of ii. has been transferred, for example in the form of a plasmid, in particular a non-integrative plasmid, more particularly a replicative plasmid.

A yeast strain of the application may especially be the I-5293 strain which was deposited with the CNCM under the Budapest Treaty on Mar. 15, 2018 (strain «TB53»).

This yeast is a S. paradoxus strain whose Srb2 gene has been deleted, and in which a nucleic acid of i. and ii have been transferred. The nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA].

The nucleic acid ii., meanwhile, corresponds to a non-integrative plasmid allowing the expression of a Luciferase model RNA (SEQ ID NO: 29) having in 3′ of a complete mutated addressing sequence (GAGm=SEQ ID NO: 14) RNA in T-bodies under the influence of a galactose promoter (GAL) [Selective Medium LEU].

A yeast strain of the application can in particular be the strain I-5294 which was deposited with the CNCM under the Budapest Treaty on Mar. 15, 2018 (strain «TB54»).

This yeast is a S. paradoxus strain whose Srb2 gene has been deleted, and in which a nucleic acid of i. and ii. have been transferred. The nucleic acid of i. is integrated in the genome of yeast, and comprises a sequence coding for the Gag-eGFP fusion protein (Ty1 Gag, in this case Gag of SEQ ID NO: 3, eGFP of SEQ ID NO: 27) under the influence a galactose promoter (Gal) [selective medium URA]. The nucleic acid ii., Meanwhile, corresponds to a non-integrative plasmid allowing the expression of a luciferase model RNA (SEQ ID NO: 29) having a partial (or minimal) addressing sequence (SEQ ID NO: 18) RNA in T-bodies under the influence of a galactose promoter (GAL) [Selective Medium LEU].

The CNCM is the National Collection of Culture of Microorganisms (Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France).

A cell of the application can in particular be a cell of one of these strains.

The yeast cell (s) may advantageously be used for the production of mRNA or lncRNA exhibiting a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of adenine and/or cytosine and/or pseudouridine residue(s), especially of adenine and/or cytosine residue(s)).

The application also relates to a microorganism culture medium, in particular to an artificial microorganism culture medium, which comprises at least one yeast cell of the application or at least one yeast strain of the application. This medium may for example be in liquid form.

The composition of this culture medium may be that of a medium adapted to the growth or multiplication of yeast cells. It may in particular comprise one or more elements among yeast extract, glucose, peptone and NaCl, more particularly at least yeast extract and/or glucose, more particularly at least yeast extract.

This medium may in particular further comprise a compound or product that would be necessary for the induction of promoter (s).

The culture medium can advantageously be used for the production of mRNA or lncRNA exhibiting a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of adenine and/or cytosine and/or or pseudouridine residue(s), especially adenine and/or cytosine residue(s)).

The application also relates to a medium for transfection or transformation of microorganisms, especially yeast, more particularly to an artificial medium for transfection or transformation of microorganisms, especially yeast. The transfection or demand transformation medium comprises at least one yeast cell of the application or at least one yeast strain of the application. This medium may be in liquid form, in particular in the form of a suspension.

The composition of this transfection or transformation medium may in particular comprise polyethylene glycol (PEG), in particular PEG 50, and may further optionally comprise denatured salmon DNA and/or lithium acetate.

The transfection or transformation medium may advantageously be used for the production of mRNA or lncRNA having a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of adenine and/or cytosine and/or pseudouridine residue(s), especially of adenine and/or cytosine residue(s).

The application also relates to a complex, a granule, a particle or a virus-like particle (VLP) (recombinant). This complex, granule, pseudo-viral particle (recombinant) is likely to be produced during the implementation of the method of production (recombinant) AR demand (and by collecting the complex, granule, pseudo-particle viral thus produced). This complex, granule, pseudo-viral particle comprises an RNA complexed with, or encapsulated by, a protein polymer, wherein the protein polymer comprises the Gag protein of a yeast Ty retrotransposon.

The nucleotide sequence of the RNA comprises said addressing sequence («b. sequence») and/or the sequence of a molecule of an RNA (in particular an mRNA or lncRNA) of interest (“sequence a.”), More particularly said addressing sequence linked to the sequence of a molecule of an RNA (in particular an mRNA or lncRNA) of interest.

Advantageously, the complex RNA, granule, pseudo-viral particle of the application, more particularly the RNA of interest, in particular the mRNA or lncRNA of interest, («a. sequence»), can be provided with a polyA tail at the 3′ end (cf. FIGS. 7A, 7B and 7C).

Advantageously, the complex RNA, granule, pseudo-viral particle of the application, more particularly the RNA, in particular the mRNA or lncRNA («a. sequence «), can be provided with a cap in the 5′ position, more particularly at its 5′ end (cf. FIGS. 7A, 7B and 7C), including a cap which comprises a 7-methylguanosine (linked to the mRNA by three phosphate). This cap can block the action of exonucleases, and may be necessary to stimulate (future) translation of said RNA into mammalian cells.

Advantageously, the complex RNA, granule, pseudo-viral particle of the application, more particularly the RNA of interest, in particular the mRNA or lncRNA («a. sequence»), can be methylated, in particular at the level of one or more of its adenine and/or cytosine and/or pseudouridine residue(s), in particular adenine and/or cytosine residue(s).

This complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise a protein that would allow the retrotransposition of the RNA (mRNA or lncRNA) of interest (transcriptase reverse, in particular), or nucleic acid that would encode such a protein. This complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise a reverse transcriptase of a yeast Ty retrotransposon, or nucleic acid encoding such a reverse transcriptase.

This complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise yeast Ty retrotransposon integrase or nucleic acid encoding such an integrase.

This complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise a protease of a yeast ty retrotransposon, or nucleic acid encoding such a protease.

More generally, this complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise a reverse transcriptase or nucleic acid encoding a reverse transcriptase. More generally, this complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise integrase or nucleic acid encoding an integrase.

More generally, this complex, granule, pseudo-viral particle (and in particular the protein polymer of this complex, granule, pseudo-viral particle) may not comprise a protease or nucleic acid encoding a protease.

The application also relates to the RNA isolated from this complex, granule, pseudo-viral particle.

The complex, granule or pseudo-viral particle may advantageously be used for the production of mRNA or lncRNA exhibiting a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end (or even a methylation of one or more adenine and/or cytosine and/or pseudouridine residue(s), especially adenine and/or cytosine residue(s)).

The application also relates to a method for producing (in vitro) DNA (in particular cDNA), which comprises producing an RNA (in particular an mRNA or lncRNA) according to the method of producing RNA from the application, and to retro-transcribe this RNA into DNA (in particular into cDNA), and to collect this DNA (or cDNA).

The application also relates to a method for producing (in vitro) protein, which comprises producing an mRNA according to the RNA production method of the application, and translating this mRNA into protein in vitro (for example in vitro). In vitro, in particular in mammalian cells, especially in human cells), and to collect this protein.

The application also relates to a method for the production of a pharmaceutical composition comprising at least one RNA of interest, in particular at least one mRNA or lncRNA of interest.

The method comprises producing at least one RNA by the RNA production method of the application, and placing the RNA in contact with (in admixture with, in suspension in) or in a pharmaceutically acceptable carrier to produce a pharmaceutical composition.

The term «pharmaceutical composition» is understood in accordance with its usual meaning in the field. It comprises the meaning of a drug, including a vaccine or immunogenic composition.

The term «pharmaceutically acceptable carrier» is meant in accordance with its usual meaning in the art. It comprises the meaning of «physiologically acceptable vehicle», including physio logically acceptable for administration to humans.

For example, a pharmaceutically (or physiologically) acceptable carrier may have one or more of the following functions: diluent functions, excipient, additive, emulsifier, dispersing agent, pH adjusting agent, preservative, surfactant, gelling agent, buffering agent, stabilizing agent, an RNA stabilizing agent (especially an agent protecting the RNA from enzymatic degradation), a solubilizing agent.

Examples of pharmaceutically (or physiologically) acceptable carriers are known to those skilled in the art, and are for example described in «Remington: The Science and Practice of Pharmacy», 20th Edition, Mack Publishing Co. and in «Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems», Ansel, Popovich and Allen Jr., Lippincott Williams and Wilkins (Ninth Edition).

Examples of pharmaceutically (or physiologically) acceptable vehicles may for example comprise injectable fluids, such as water, physiological saline, buffers, emulsions.

The fact that the RNA produced in accordance with the application can have a polyA tail at the 3′ end and/or a 7-methylguanosine (m7G) cap at the 5′ end, or even a methylation of adenine and/or cytosine and/or pseudouridine residue(s), in particular adenine and or cytosine, makes it directly competent for translation into mammalian cells, especially in human cells.

In the application, unless otherwise specified, or the context dictates otherwise, all terms have their usual meaning in the area (s) concerned. The term «comprising», with which «including» or «containing» is synonymous, is an open term, and does not exclude the presence of one or more element (s), ingredient (s) or step (s) of additional method (s) that would not be explicitly stated, while the term «consistent» or «constituted» is a closed term, which excludes the presence of any additional element, step, or ingredient that does not would not be explicitly exposed. The term «substantially consisting of» or «essentially consisting of» is a partially open term, which does not exclude the presence of one or more element (s), ingredient (s) or additional step (s) in the to the extent that such element (s), ingredient (s) or additional step (s) do not materially affect the basic properties of the invention.

Therefore, the term «comprising» (or «comprises (comprise)») comprises the terms «consisting», «consisting», as well as the terms «consisting essentially» and «essentially consisting».

In order to facilitate the reading of the application, the description has been separated into various paragraphs and sections. These separations should not be considered to disconnect the substance of a paragraph or section from that of another paragraph or section. On the contrary, the description encompasses all possible combinations of the different paragraphs, sections and sentences it contains.

The content of the bibliographic references cited in the application is specifically incorporated by reference into the content of the application.

The following examples are given for illustrative purposes only. They are in no way limiting.

The yeast cells thus transformed produce T-retrosomes (T-bodies or pseudo-viral particles) which contain the heterologous RNA, without retro-transcribing this heterologous RNA or retro-integrating it into the genome.

The heterologous RNA thus produced were purified.

Material and Methods

1. Strains and Plasmids Used

Strains:

A strain of Escherichia coli DH5 bacteria is available from ATCC® under the number 67877™

A wild yeast strain Saccharomyces paradoxus is available from ATCC® under the number 76528™

Yeast strain YAM13 is a strain of S. paradoxus MATalpha Ty0 leu2 lys2 ura3.

The yeast strain YAM13 ΔSrb2 is a S. paradoxus YAM13 strain whose Srb2 gene has been deleted.

The YAM13 yeast strain ΔSpt21 is a S. paradoxus YAM13 strain, whose Spt21 gene has been deleted.

A wild yeast strain Saccharomyces cerevisiae is available from ATCC® under the number 52530™.

ATCC® is the American Type Culture Collection (10801 University Blvd.; Manassas, Virginia 20110-2209; USA.).

S. paradoxus is naturally devoid of retrotransposon, in particular Ty1 retrotransposon, unlike S. cerevisiae which is naturally provided with Ty1 retrotransposon.

Construction encoding the Gag protein (cf. FIG. 7A):

For the construction encoding the Gag protein, two plasmids were used, one to amplify the GAG sequence (SEQ ID NO: 1) and the other to express the Gag protein with and without a poly-histidine tag (tag 6-His).

The DNA, RNA and protein sequences of the 6-His tag are the sequences of SEQ ID NO: 4, 5 and 6, respectively.

The first plasmid (pBDG1 130Apo 1) contains the GAG sequence and served as a template for the amplification and addition of the 6-His tag upstream and/or downstream (SEQ ID NO: 7, SEQ ID NO: 9 and SEQ ID NO: 11) of this sequence by PCR.

The second plasmid pAG425GAL-ccdB was used to express Gag proteins with or without 6-His tag in the N-terminal and/or C-terminal position in yeast (S. paradoxus YAM13 ΔSrb2). The proteins were inducibly expressed by the presence of the galactose GAL1 promoter. This plasmid consists of an origin of bacteria and eukaryotic replication (2μ-20-50 copies per cell) which allows the amplification of the plasmid in E. coli DH5 bacteria and an expression of the proteins in the yeast. In order to specifically select the cells transfected with the plasmid, different selection markers were used. For the E. coli bacteria, the ampicillin resistance gene allowed for the selection of transfected bacteria and the ccdB gene was used to induce the death of transfected bacteria that did not recombine between the sequence of interest and the plasmid. For the yeast strain, the leucine synthesis gene (LEU2) allowed the selection of yeasts transformed by the plasmid.

The YAM13 yeast ΔSrb2 is auxotrophic for this amino acid and the transformation with the plasmid allows the yeast to grow on a medium lacking leucine (−LEU).

The expression medium of the proteins of interest by the yeasts was thus made on a medium −LEU and containing 2% of galactose.

A similar plasmid construct was produced to express the Gag protein (SEQ ID NO: 3 in fusion with the eGFP protein within the plasmid pAG426-ccdB-eGFP (cf. FIG. 7A). The plasmid pAG426-ccdB-eGFP has the uracil synthesis gene (URA3) which allows the selection of yeasts transformed by the plasmid. The YAM13 yeast ΔSrb2 is auxotrophic for this amino acid and the transformation with the plasmid allows the yeast to grow on a medium lacking in uracil (−URA).

The DNA, RNA and protein sequences of eGFP are the sequences of SEQ ID NO: 25, 26 and 27, respectively.

Construction encoding the heterologous RNA having the Gag addressing sequence (cf. FIG. 7B; cf. construction ii) of FIG. 6A):

An mRNA encoding eGFP (Enhanced Green Fluorescent Protein) has been implemented as heterologous RNA.

Luciferase encoding mRNA has been implemented as heterologous RNA and the luciferase DNA, RNA and protein sequences are the sequences of SEQ ID NOs: 28, 29 and 30, respectively.

The Gag addressing sequence is a retrosomal addressing RNA sequence (RNA sequence which addresses the heterologous RNA to which it is linked, to the retrosomes which are otherwise formed by the Gag protein). The retrosomal addressing sequence is a non-coding Gag sequence (Gag coding sequence which has been modified by deletion of the Gag expression promoter, non-coding Gag sequence which can also be designated as «mini-GAG» or «MiniGag» or «EndGAG»).

The DNA and RNA sequences of the Gag addressing sequence are the sequences of SEQ ID NO: 13 and 14, respectively.

The DNA encoding the heterologous mRNA and the DNA encoding the Gag addressing sequence were inserted into a plasmid (plasmid pAG425-GAL-ccdB).

2. Cloning of the episomal plasmid encoding GAG protein

2.1. GAG sequence with and without Tag 6-His

2.1.1. Amplification of the GAG sequence for the addition of Tag 6-His by PCR

The strategy adopted for cloning is a strategy based on the ligation between two nucleotide sequences having cohesive ends obtained by enzymatic digestion.

Primers RQ3 and FQ4 were used to amplify GAG and add restriction sites to the extremities. The PCR reaction was carried out with final concentrations of 0.3 μM primers, 1× KAPA HIFI HOTSTART READYMIX PCR™ and 200 ng/μL of DNA. Dimethylsulfoxide (DMSO), at a final concentration of 5%, was added for the amplification reactions with the FQ4/RQ4 and FQ3/RQ4 primer pairs to avoid the secondary structures that can be taken up by the primers. The template DNA used is the plasmid pBDG1 130 containing the GAG sequence to be amplified.

The denaturation was carried out at 95° C. for 30 min, followed by 30 cycles of 20 sec at 98° C. and then 15 sec at 65° C. (pair of primers FQ3/RQ3) or at 60° C. (pairs of primers FQ4/RQ4, FQ3/RQ4 and FQ4/RQ3), and 1 min at 72° C. Terminal elongation was done at 72° C. for 3 min. At the end of the amplification reaction, 8 of PCR product were added with 2×5× loading buffer. The mixture obtained was deposited on a 0.6%+5% ethidium bromide (BET) agarose gel and the migration is then carried out for 1 hour at 80 V. The size marker used is 1 KB DNA LADDER™ (NEW ENGLAND BIOLABS). After migration, a revelation under UV allowed to verify that there was specific amplification.

Specific PCR products were extracted with CLEAN-UP PCR Kit, GEL EXTRACTION™ (MACHEREY-NAGEL) according to the supplier's recommendations. The extracted fragments are quantified with NANODROP and then digested with HindIII and SpeI to be ligated with the expression plasmid pAG425GAL-ccdB.

2.1.2. ligation

Enzymatic digestion with HindIII and SpeI of the episomal expression plasmid pAG425GAL-ccdB and inserts (GAG with C-terminal 6-His tag (SEQ ID NO: 7), GAG with N-terminal 6-His tag (SEQ ID NO: 9), GAG with C-terminal and N-terminal 6-His tag (SEQ ID NO: 11) made it possible to linearize the plasmid and form cohesive protruding ends between the plasmid and the various inserts. The digestion by the two restriction enzymes was made in one reaction under the following conditions: 1 μg of DNA (insert or plasmid), 5 U/mL of each of the two enzymes HindIII and SpeI, IX Buffer CUTSMART™ 10× for a reaction volume of 40 μL. The digestion was carried out for 1 h30 at 37° C. After digestion, the reaction mixture is deposited on 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION™ PCR kit. (MACHEREY-NAGEL) according to the supplier's recommendations.

After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the different recombinant plasmids, an amplification by E. coli DH5α was carried out of plasmids constructed pAG425GAL-GAG, pAG425GAL-6His-GAG pAG425GAL-GAG-6His, pAG425GAL-6His-GAG-6His.

2.2 GAG-eGFP Merge Sequence

2.2.1. Amplification of the GAG sequence for fusion with eGFP

The PCR reaction was carried out with final concentrations of 0.3 μM primers, 1× KAPA HIFI HOTSTART READYMIX PCR™ and 200 ng/μL of DNA. Dimethylsulfoxide (DMSO), at a final concentration of 5%, was added for the amplification reactions with the FQ5/RQ5 primer pairs. The template DNA used is the plasmid pBDG1130 containing the GAG sequence to be amplified.

At the end of the amplification reaction, 8 μL of PCR product were added 2 μL of 5× loading buffer. The mixture obtained was deposited on a 0.6%+5% ethidium bromide (BET) agarose gel and the migration is then carried out for 1 hour at 80 V. The size marker used is 1 KB DNA LADDER™ (NEW ENGLAND BIOLABS). After migration, a revelation under UV allowed to verify that there was specific amplification.

Specific PCR products were extracted with CLEAN-UP PCR Kit, GEL EXTRACTION™ (MACHEREY-NAGEL) according to the supplier's recommendations. The extracted fragments are quantified with NANODROP and then digested with SpeI and EcoRI to be ligated with the expression plasmid pAG426GAL-ccdB-eGFP.

2.2.2. Digestion and ligation

The enzymatic digestion with SpeI and EcoRI of the pAG426GAL-ccdB-eGFP expression plasmid and the insert (GAG without stop codon (SEQ ID NO: 37) made it possible to linearize the plasmid and form cohesive protruding ends between the plasmid and the insert. The digestion by the two restriction enzymes was made in one reaction under the following conditions: 1 μg of DNA (insert or plasmid), 5 U/mL of each of the two enzymes HindIII and Spe1, IX Buffer NEB 2.1 IX for a reaction volume of 40 μL. The digestion was carried out for 1 h30 at 37° C. After digestion, the reaction mixture is deposited on 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION™ PCR kit. (MACHEREY-NAGEL) according to the supplier's recommendations. After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB).

After obtaining the different recombinant plasmids, an E. coli DH5a amplification was carried out of the plasmid construct pAG426GAL-GAGeGFP.

2.3 GAG-eGFP-6-His sequence with and without 3MS2

2.3.1. Synthesis and digestion of the GAG-eGFP-6-His-3MS2 sequence

The «GAG-eGFP-6HIS-3MS2» cassette is ordered (SEQ ID NO: 38) and synthesized by GenScript and inserted into the plasmid pUC57 (pUC57-GeGHM). This sequence codes for the Gag-eGFP fusion protein with a C-terminal histidine tag with 3′ of this sequence three MS2 repeats (SEQ ID NO: 35).

Plasmid pUC57-GAG-eGFP-6HIS (pUC57-GeGH) is cloned by removing the sequence 3MS2 (SEQ ID NO: 35) by NotI digestion followed by ligation at 25° C. for 5 min (Quick ligation kit NEB).

Plasmids pUC57-GeGHM and pUC57-GeGH are digested with the restriction enzymes Spe1 and KpnI. The fragment corresponding to the sequence GAG-eGFP-6HIS-3MS2 (SEQ ID NO: 38) (2369 bp) and GAG-eGFP-6HIS (SEQ ID NO: 39) (2101 bp) are purified after deposition on gel 0.6% agarose to verify digestion and gel extraction of the fragment of interest was made with CLEAN-UP GEL EXTRACTION™ PCR Kit (MACHEREY-NAGEL) according to the supplier's recommendations.

2.3.2. Ligation

Spel and KpnI enzymatic digestion of the pAG426GAL-ccdB-eGFP expression plasmid and GAG inserts without a stop codon (SEQ ID NO: 37) made it possible to linearize the plasmid and form cohesive protruding ends between the plasmid and the inserts. GAG-eGFP-6HIS-3MS2 (SEQ ID NO: 38) and GAG-eGFP-6HIS (SEQ ID NO: 39). After digestion, the reaction mixture is deposited on 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION PCR™ kit. (MACHEREY-NAGEL) according to the supplier's recommendations. After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the different recombinant plasmids, amplification with E. coli DH5a was carried out.

After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the various recombinant plasmids, an amplification by E. coli DH5α was carried out of the plasmids constructed pAG426GAL-GeGHM and pAG426GAL-GeGH.

3. Cloning of the Integrative Plasmid Encoding the GAG Protein

3.1. Amplification of the GAL-GAG-eGFP sequence by PCR

The GAL-GAG-eGFP sequence encoding the Galactose promoter Gag-eGFP fusion protein (SEQ ID NO: 42) was amplified by PCR. The amplification primers make it possible to have the SacI and KpnI restriction sites upstream and downstream of the amplified sequence.

At the end of the amplification reaction, 8 μL of PCR product were added 2 of 5× loading buffer. The mixture obtained was deposited on a 0.6%+5% ethidium bromide (BET) agarose gel and the migration is then carried out for 1 hour at 80 V. The size marker used is 1 KB DNA LADDER™ (NEW ENGLAND BIOLABS). After migration, a revelation under UV allowed to verify that there was specific amplification.

3.2. ligation

The integrative yeast plasmid pRS306 has a URA3 marker and a Ampiciline AmpR resistance gene.

The pRS306 expression plasmid underwent enzymatic digestion with SacI and KpnI.

The digestion by the two restriction enzymes was made in one reaction under the following conditions: 1 μg of DNA (insert or plasmid), 5 U/mL of each of the two enzymes Sac1 and KpnI, IX of Buffer NEB 1.1 IX for a reaction volume of 40 μL. The digestion was carried out for 1 h30 at 37° C. After digestion, the reaction mixture is deposited on 0.6% agarose gel in order to verify that there has been digestion and carry out a gel extraction of the fragment of interest was made with the PCR kit CLEAN-UP GEL EXTRACTION™ (MACHEREY-NAGEL) according to the supplier's recommendations. The ligation is carried out using the Gibson Assembly kit under the following conditions: Gibson Master Mix+50 ng of pRS306 vector digested with SacI/KpnI (427 lpb)+0.5 pM, ie 926 ng of GAL-GAG-EGFP PCR+Qsp H20 10 μL. The reaction is incubated at 50° C. After obtaining the different recombinant plasmids, amplification with E. coli DH5a was carried out.

4. Cloning of the plasmid encoding heterologous RNA

An mRNA encoding eGFP (Enhanced Green Fluorescent Protein) has been implemented as heterologous RNA. The DNA, RNA and protein sequences of eGFP are the sequences of SEQ ID NO: 25, 26 and 27, respectively.

An mRNA encoding luciferase has been implemented as heterologous RNA. The DNA, RNA and protein sequences of luciferase are the sequences of SEQ ID NO: 28, 29 and 30, respectively

4.1 Luciferase sequence as heterologous RNA

4.1.1. EndGAG Sequence as Addressing Sequence

The «Luc-EndGAG-3M52» cassette is ordered (SEQ ID NO: 43) and synthesized by GenScript and inserted into the plasmid pUC57 (pUC57-LEGM). This sequence encodes for the 3 luciferase protein of this sequence the addressing sequence in the EndGAG T-bodies followed by three MS2 repeats (SEQ ID NO: 35).

Plasmid pUC57-Luc-EndGAG (pUC57-LEG) is cloned by removing the sequence 3MS2 (SEQ ID NO: 35) by NotI digestion followed by ligation at 25° C. for 5 min (Quick ligation kit NEB).

Plasmids pUC57-LEGM and pUC57-LEG are digested with the restriction enzymes Spe1 and HindIII. The fragment corresponding to the sequence Luc-EndGAG-3MS2 (SEQ ID NO: 43) (3425 bp) and Luc-EndGAG (SEQ ID NO: 44) (3039 bp) are purified after depositing on a 0.6% agarose gel in order to verify that digestion and gel extraction of the fragment of interest were made with the CLEAN-UP GEL EXTRACTION PCR™ Kit (MACHEREY-NAGEL) according to the supplier's recommendations. Enzymatic digestion with SpeI and KpnI of the pAG425GAL-ccdB expression plasmid and the Luc-EndGAG-3MS2 (SEQ ID NO: 43) and Luc-EndGAG (SEQ ID NO: 44) inserts made it possible to linearize the plasmid and form cohesive protruding ends between the plasmid and the inserts. After digestion, the reaction mixture is deposited on a 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION™ PCR kit. (MACHEREY-NAGEL) according to the supplier's recommendations.

After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the different recombinant plasmids, an amplification by E. coli DH5a was carried out of the plasmids constructed pAG425GAL-LEGM and pAG425GAL-LEG.

4.1.2 GAGm sequence as a addressing sequence

The sequence «GAGm» is controlled (SEQ ID NO: 13) and synthesized by GenScript and inserted into the plasmid pUC57 (pUC57-Gm). This sequence is the addressing sequence in complete and mutated T-bodies (SEQ ID NO: 14).

The plasmid pAG425GAL-LEGM is digested with the restriction enzyme NdeI and then partially with the restriction enzyme NotI. The fragments corresponding to the plasmid released from the EndGAG sequence (9850 bp) and to the plasmid released from the sequence EndGAG and 3MS2 (9464 bp) are purified after deposition on 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION™ PCR kit (MACHEREY-NAGEL) according to the supplier's recommendations.

The plasmid pUC57-GAGm is digested with the restriction enzymes NdeI and NotI. The fragment corresponding to GAGm (1336 bp) is purified after deposition on 0.6% agarose gel and a gel extraction of the fragment of interest was made with CLEAN-UP GEL EXTRACTION™ PCR kit (MACHEREY-NAGEL) according to the supplier's recommendations.

After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the various recombinant plasmids, an amplification by E. coli DH5a was carried out of plasmids constructed pAG425GAL-LGmM and pAG425GAL-LGm.

4.2 Sequence eGFP as heterologous RNA

The eGFP sequence is amplified by PCR from plasmid pCMV-eGFP. The amplification primers make it possible to have the Spel and Alel restriction sites upstream and downstream of the amplified sequence. PCR was performed using the KAPA HIFI HOTSTART READYMIX PCR kit (KAPABIOSYSTEMS) according to the supplier's recommendations, using the primer pair. At the end of the amplification reaction, 8 μL of PCR product were added 2 of 5× loading buffer. The mixture obtained was deposited on a 0.6%+5% ethidium bromide (BET) agarose gel and the migration is then carried out for 1 hour at 80 V. The size marker used is 1 KB DNA LADDER™ (NEW ENGLAND BIOLABS). After migration, a revelation under UV allowed to verify that there was specific amplification.

Plasmids pAG425GAL-LGmM, pAG425GAL-LGm, pAG425 GAL-LEGM and pAG425GAL-LEG are digested with restriction enzymes SpeI and AleI. The fragments corresponding to the plasmids released from luciferase are purified after deposition on 0.6% agarose gel and a gel extraction of the fragment of interest was made with the CLEANUP GEL EXTRACTION™ (MACHEREY-NAGEL) PCR kit according to supplier's recommendations.

After quantification of the extracts, the ligation was made according to a molar ratio of pDNA/insert of 1: 3. The reaction was carried out at 25° C. for 5 min (Quick ligation kit NEB). After obtaining the different recombinant plasmids, amplification by E. coli DH5α was carried out using plasmids constructed pAG425GAL-eGFPGmM, pAG425GAL-eGFPGm, pAG425GAL-eGFPEGM and pAG425 GAL-eGFPEG.

5. Amplification of recombinant plasmids by E. coli DH5α

The transformation of E. coli DH5a bacteria was done by adding 5 μL of the ligation product for 50 μL of competent E. coli DH5a bacteria.

A 30 min incubation on ice was made before inducing 30s heat shock at 42° C. The samples were then incubated on ice for 5 minutes before putting them at 37° C. for 50 min in 300 of SOC medium. Transformant bacteria were plated on LB+100 μg/mL ampicillin plates.

After culture of the transformants, several clones were transplanted and taken up in liquid medium in order to extract the recombinant plasmids. The extraction was done using the PLAS MID DNA PURIFICATION™ kit (MACHEREY-NAGEL) according to the supplier's recommendations. After purification, enzymatic digestion with HpaI (NEW ENGLAND BIOLABS) is carried out. This digestion was carried out under the same conditions as those by HindIII/SpeI (NEW ENGLAND BIOLABS). For the recombinant plasmids, two restriction sites were observed while for the non-recombinant plasmids a single restriction site was observed. Three profiles could be found: linearized plasmid not digested with HindIII/SpeI (9249 bp), linearized plasmid digested with HindIII/SpeI (7495 bp) and recombinant linearized plasmid (6752 bp+2036 bp). Sequencing was done for the recombinant plasmids.

6. Yeast transformation

6.1. Transformation with episomal plasmid

The different episomal recombinant plasmids obtained were used to transform the yeasts S. paradoxus and S. cerevisae (cf. FIGS. 7A and 7B).

The yeasts are washed with water and then with 0.1 M lithium acetate (LiOAc). The pellet was resuspended in 240 μL, 50% PEG, 36 μL of 1 M LiOAc+8 μL of plasmid DNA+5 μL of denatured salmon DNA. The resulting mixture was stirred for 1 min and then incubated for at least 30 min at 25° C. Heat shock was induced at 42° C. or 37° C. for 20 min. The cells are washed and resuspended in sterile distilled water. The transformed yeasts were plated on the leucine-free selective box (in the case of the transformation of a plasmid possessing the Leu2 gene whose backbone is named pAG425) into Uracil (in the case of the transformation of a plasmid containing the URA3 gene whose backbone is named pAG426), Leucine and Uracil (in the case of the transformation of two plasmids, one having the URA3 gene whose backbone is named pAG426 and the other having the Leu2 gene whose backbone is named pAG425).

Examples of S. paradoxus strains illustrating this transformation with episomal plasmid have been deposited with the CNCM under the Budapest Treaty, see Table 1 below.

6.2. Transformation with integrative plasmid

The plasmid pRS306-GAL-GAG-EGFP is linearized by digestion with AatII FastDigest (Thermo Scientific) under the following conditions: 2 μL of AatII enzyme+2 μg of pRS306-GAL-GAG-EGFP pRNA+5 μL of Green FastDigest buffer+50 H₂0. The reaction is incubated for 25 min at 37° C. After digestion, the reaction mixture is deposited on 0.6% agarose gel in order to verify that there has been digestion and a gel extraction of the fragment of interest was made with the CLEAN-UP GEL EXTRACTION™ PCR kit. (MACHEREY-NAGEL) according to the supplier's recommendations.

The yeasts are washed with water and then with 0.1 M lithium acetate (LiOAc). The pellet was resuspended in 240 μL, 50% PEG, 36 μL of 1 M LiOAc+8 μL of plasmid DNA+5 μL of denatured salmon DNA. The resulting mixture was stirred for 1 min and then incubated for at least 30 min at 25° C. Heat shock was induced at 42° C. or 37° C. for 20 min. The cells are washed and resuspended in sterile distilled water. The transformed yeasts were plated on the leucine Uracil-free selective dish (in the case of the transformation of a plasmid possessing the URA3 gene whose backbone is called pRS306), Leucine and Uracil (in the case of two plasmids, one with the URA3 gene whose backbone is named pRS306 and the other with the Leu2 gene whose backbone is named pAG425).

Examples of S. paradoxus strains illustrating this transformation with integrative plasmid have been deposited with the CNCM under the Budapest Treaty, see Table 1 below.

7. Induction of expression and extraction of T-bodies

7.1. Galactose induction

In order to produce T-bodies and to express the Gag protein (SEQ ID NO: 3) with or without a 6-His tag (SEQ ID NO: 8, SEQ ID NO: 10 and SEQ ID NO: 12), galactose induction is performed.

The cells are centrifuged for 10 min at 3000 rpm and then rinsed twice with sterile water. The cells are then resuspended in the appropriate selective medium for transformed episomal and/or integrative plasmids devoid of glucose and supplemented with 2% galactose. The induction was carried out overnight at 25° C. Various mechanical and chemical extraction techniques have been tested to optimize the conditions for obtaining T-retrosomes (T-bodies or pseudo-viral particles).

7.2. Mechanical lysis by balls

The yeasts were centrifuged for 3 mM at 3000 rpm and then washed in cold lysis buffer (50 mM Tris pH 7.6, 50 mM NaCl, 5 mM MgCl 2, 0.1% NPA, 1 mM β-mercaptoethanol, IX PROTEASE INHIBITOR COMPLETE MINI EDTA FREE™ 0.4 U/μL RNASE INHIBITOR™). The cells are centrifuged. The pellet is taken up in cold lysis buffer supplemented with beads. The resulting mixture was vortexed on ice for 1 mM A centrifugation of 2 mM at 2000g is made and the supernatant was collected and then centrifuged for 10 mM at 10000 g. The pellet was taken up in cold lysis buffer and incubated for 30 min at room temperature. Centrifugation for 10 mM at 10,000 g is made and the pellet is taken up in cold lysis buffer.

7.3. Mechanical lysis by sonication

The yeasts were centrifuged for 10 mM at 10000 g and then resuspended in BINDING BUFFER™ IX containing 80 U/mL of lyticase to obtain spheroplasts. The suspension was incubated for 10 mM at 25° C. Following this incubation, the yeasts were lysed by sonication on ice at a rate of 10×15 sec at 70% with 15 sec of cooling between each sonication. Centrifugation for 15 mM at 5000 g was done to collect inclusion bodies and cell debris.

7.4. Chemical lysis in sodium hydroxide

The yeasts were centrifuged and resuspended in a volume-to-volume mixture of H2O and 0.2M NaOH. The resulting mixture was incubated at room temperature for 5 mM and then centrifuged for 2 mM at 14000 rpm. The pellet obtained was taken up in LAEMMLI™ 2× to be denatured for 15 mM at 95° C. After denaturation, a 2 mM centrifugation at 8000 rpm was done and the supernatant was recovered in a new tube to be stored at 4° C.

7.5. Y-PERTM chemical lysis

Y-PERTM YEAST PROTEIN EXTRACTION REAGENT™ Kit (THERMO SCIENTIFIC) was used as recommended by the supplier.

7.6. Mechanical lysis by high pressure hom*ogenization

Yeasts are lysed by high pressure hom*ogenization 3 passages at 2000 bar in lysis buffer (50 mM Tris pH 7.6, 50 mM NaCl, 5 mM MgCl2, 0.1% NP-40, 1 mM β-mercaptoefhanol, 1× complete inhibitor protease mini EDTA free, 0.4 μL RNase inhibitor) (V/V).

8. Protein dosage

The determination of the protein extracts was carried out by the BCA method (INTERCHIM).

9. Western SDS-PAGE Transfer

The extracted proteins were separated on SDS-PAGE gel in 1× migration buffer. The separation gel used contained 12% acrylamide.

The migration was made during 1h at 180V. The size marker, PRECISION PLUS PROTEIN™ KALEIDOSCOPE™ (BIO-RAD), was deposited at 10 μL/well After migration, the proteins were transferred to a polyvinylidene fluoride (PVDF) membrane by semi-dry transfer. The PVDF membrane was previously activated with methanol before mounting the transfer. The assembly was done as follows, WHATMANN papers moistened in IX transfer buffer, PVDF membrane, 12% acrylamide separation gel and WHATMANN papers moistened in IX transfer buffer. The transfer was made at 2.5 A; 25 V for 7 mM. The membrane was recovered and then washed twice for 10 min with TBS +0.1% TWEEN (TBST). Saturation was done for 1 hour in 0.1% TBST+3-5% milk. After saturation, three 15 mM washes were made in 0.1% TBST and then the primary antibodies were added for overnight incubation at 4° C. Mouse anti-Ty1 primary antibodies and anti-6-His rabbit antibodies were diluted 1/2000 in 0.1% TBST+3% milk. After incubation with the primary antibodies, the membrane was washed three times for 15 mM at 0.1% TBST and the secondary antibodies were added for incubation at room temperature with shaking. The anti-mouse IgG secondary antibodies (HRP) and the anti-rabbit IgG antibody (HRP) were diluted to 1/20 000 in 0.1% TBST+3% milk. After incubation with the secondary antibodies, the membranes were washed 3 times 15 min in 0.1% TBST. The membranes are then revealed by the CLARITY WESTERN ECL BLOTTING SUBSTRATE™ (BIO-RAD). A volume-to-volume (1:1) blend of CLARITY WESTERN PEROXIDE REAGENT™ and CLARITY WESTERN LUMINOL/ENHANCER™ was made and applied to the membranes. The reading was done at PIXI™ or by photographic film.

10. Immunofluorescence analysis with a confocal microscope

In order to verify that the presence of the tag 6-His (SEQ ID NO: 5) does not interfere with the formation of T retrosomes (T-bodies), a marking of these T-bodies was made using the couple anti-Ty1/FITC antibodies.

Before labeling, the induction of the expression of the different proteins was made overnight at 25° C. in −UEU +2% galactose.

The yeasts were then fixed with 4% formaldehyde for 1 h at 25° C. The cells were recovered after centrifugation for 3 min at 2000 rpm and washed three times in 0.1 M KHPO₄ solution; pH 6.5 and once in a 1.2M solution of sorbitol; 0.1M KHPO₄; pH 6.5. The pellet was resuspended in a solution of 1.2M sorbitol; 0.1M KHPO₄; pH 6.5, then the pellet was added volume to volume in a solution composed of 1.2M sorbitol; 0.1M KHPO₄; pH 6.5 with 1/100 β-mercaptoethanol added. The resulting mixture was incubated for 5 min at room temperature. Lyticase was added at 50 U/mL final before incubation at 25° C. for 30 min. The spheroplasts obtained were recovered by centrifugation for 2 min at 2000 rpm. Washing was done with a 1.2M solution of sorbitol; 0.1M KHPO₄; pH 6.5. Cold methanol was added at equivalent volume for 6 min and then cold acetone for 30 s.

A washing with PBS supplemented with 1% BSA was done before saturating the yeasts for 5-10 min in this same solution. The saturation solution was removed and the anti-Ty1 mouse primary antibody diluted 1/1000 in PBS was contacted with the yeast overnight at 4° C. The following day, the yeasts were washed 5 times with PBS+1% BSA. The fluorescein-coupled anti-mouse IgG secondary antibody (FITC) diluted 1/2000 in PBS+1% BSA was incubated for 2 h at room temperature in the dark. After incubation, 5 washes in PBS+1% BSA and one wash with a 1.2M solution of sorbitol; 0.1M KHPO₄; pH 6.5 were made. The yeasts were resuspended in the latter solution before being deposited between slides and lamellae.

11. Fluorescence analysis by flow cytometry

To determine which extraction technique makes it possible to recover the most Gag positive cells (SEQ ID NO: 3), a pair of antibodies coupled to fluorescence was used and then the fluorescence was analyzed by flow cytometry.

Per 100 protein extracts, 400 PBS supplemented with 10% fetal calf serum (FCS) and 0.1% RNAsin (PROMEGA) were added.

The whole was incubated at 4° C. for 30 min. The mouse anti-Ty1 primary antibody diluted 1/100 was incubated for 1 h at 4° C. The anti-mouse IgG secondary antibody Cy5 diluted 1/200 was added and incubated for 30 min at 4° C. The samples were analyzed by flow cytometry.

12. Purification by nickel affinity chromatography

Purification was done using the HIS BIND™ RESIN CHROMATOGRAPHY kit (NOVAGEN).

13. RNA extraction

After protein purification, RNA extraction was performed to quantify the proportion of Gag-specific RNA.

For a minimum volume of 200 μL of purified T-bodies, a volume of phenol acid/chloroform was added. The mixture obtained was vortexed for 1 min and then centrifuged for 5 min at 14,000 rpm. The supernatant was recovered and a volume of chloroform added. The mixture obtained was vortexed for 1 min and then centrifuged for 5 min at 14,000 rpm. The supernatant was recovered and 1/10 volume 3 M sodium acetate pH 5.2 and 2.5 volumes (supernatant+sodium acetate) of 100% ethanol. The resulting mixture was incubated at −20° C. overnight. The next day, the resulting mixture was centrifuged for 15 min at 14000 rpm at 4° C. The dried pellet was resuspended in nuclease-free water (Nuclease Free Water). The extracted RNAs were quantified with NANODROP™

14. qRT-PCR

Extracted RNAs were reverse transcribed (reverse transcription; RT) for the production of complementary DNA (cDNA) by the REVERTAID RT REVERSE TRANSCRIPTION™ kit (THERMOFISHER SCIENTIFIC), according to the supplier's recommendations, using 500 ng of RNA by reaction with the random hexamer primer (random hexamer primer) of the kit.

The cDNAs obtained are quantified with NANODROP™. QPCR is performed using the QUANTIFFAST SYBR GREEN PCR™ Kit (QUIAGEN), as recommended by the supplier. The standard range was made using plasmid pBDG1130 of λg<1 μL at 0.1 μg/μL. The primers used: qGAGF (SEQ ID NO: 23) and qGAGR (SEQ ID NO: 24) allowed the amplification of 277 bp of GAG. The program used for the amplification was as follows: first a preincubation at 50° C. for 2 min, then a denaturation at 95° C. for 10 min, followed by cycles at 95° C. for 15s, at 60° C. for 30s, at 72° C. for 30s. A melting curve was produced at the end of the experiment to check the absence of contaminants: at 95° C. for 15 s then at 50° C. for 1 min and at 95° C. with acquisitions every 5° C.

Results

Selection and modification of yeast strains (for robust mRNA production in T-bodies)

The analysis of the expression of the Gag protein (49 kDa, SEQ ID NO: 3) on cell lysate samples of S. cerevisiae and S. paradoxus yeast confirms that the S. paradoxus strain is devoid of the retrotransposition element. Ty1 (cf. FIG. 1A).

Transformation of yeast S. paradoxus with a plasmid encoding eGFP under the control of a galactose-inducible promoter shows that the ΔSpt21 and/or ΔSrb2 transcriptional mutations allow a significant increase in the number of eGFP positive cells as well as in the intensity of fluorescence. The results are illustrated in FIG. 1B.

Construction of expression vectors for T-bodies formation and EGFP mRNA addressing in T-bodies

The confocal fluorescence microscopy analyzes of the expression of the eGFP and the Gag-eGFP fusion protein in the S. paradoxus yeast and the ΔSpt21 and ΔSrb2 transcriptional mutants were carried out. The results are illustrated by FIGS. 2A and 2B. An increase in the number of T-bodies positive cells (FIG. 2A) as well as an increase in the number of T-bodies per cell in the ΔSpt21 and ΔSrb2 transcriptional mutants are observed (FIG. 2B). Flow cytometric analysis of the expression of T-bodies eGFP (Gag-eGFP fusion protein) in the transcriptional mutant of the yeast S. paradoxus ΔSrb2 after an 8-hour treatment with tunicamycin (TUNI) was carried out (Tunicamycin is an antibiotic produced by bacteria of the genus Streptomyces that have an action on N-glycosylation and on the cell cycle). The results are illustrated in FIG. 2C. An 8-hour treatment with tunicamycin causes an increase in the number of T-bodies (11% YS 48%).

Fluorescence in situ hybridization experiments (fluorescence in situ hybridization, FISH) were performed to locate the model mRNAs encoding the eGFP protein by using primers addressing Cy5-labeled eGFP mRNA on yeast S. paradoxus ΔSrb2 transformed with a Gag-eGFP fusion plasmid or with a MiniGag-eGFP fusion plasmid. The results are illustrated by FIGS. 3A and 3B.

Perfect collocation between the Gag protein and the corresponding mRNA is observed (FIG. 3A). A study was conducted to look for deleted Gag nucleotide sequence that allows addressing of mRNAs in T-bodies. This sequence is called MiniGag in FIG. 3B.

Purification of T-bodies

The protocol for extracting T-bodies from yeast S. paradoxus expressing the Gag-eGFP fusion protein after galactose induction is based on a mechanical yeast lysis followed by differential centrifugations.

Two different mechanical extraction techniques (ball lysis and sonication method) were tested. The results are illustrated by FIGS. 4A (glass beads) and 4B (sonication). After extraction with the aid of glass beads (FIG. 4A), the T-bodies appear as spherical-shaped particles with a diameter of 200 nm. On the other hand, the method of sonication lysis induces a destruction of T-bodies with debris observable by electron microscopy (FIG. 4B). The method of lysis by the beads seems to be the best suited to get the most integrity T-bodies.

These constructs were transformed into the mutant ΔSrb2 of the yeast S. paradoxus. The formation of T-bodies was observed by immunofluorescence (FIG. 5A). Expression of the Gag protein was verified by Western blotting (FIG. 5B). The purification was carried out on a nickel column by competition with imidazol. The results are shown in FIG. 5C (elution of T-bodies at 800 mM imidazole for GAG-6His construction).

Yeasts thus transformed produce retrosomes containing the heterologous RNA, without retro-transcribing this RNA or retro-integrating it.

Samples of some of these yeasts were deposited with the CNCN under the Budapest Treaty.

CNCM is the National Collection of Culture of Microorganisms (Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France).

RNAs were produced as described in Example 1 and were transfected (liposomally) into mammalian cells, in this case dendritic cells.

RNA transfection experiments were performed in mouse dendritic cells (DC2.4 line, available from THERMOFISHER SCIENTIFIC).

The eGFP mRNAs produced in the T-bodies of this yeast were extracted and purified as described in Example 1 above (extraction of the T-bodies mechanically-balls, then purification of the eGFP mRNAs contained in these T-bodies), then vectorized on cationic liposomes (liposomes 100 or Lip100). Liposomes 100 are composed equally of a cationic lipid (lipid 1), and a neutral colipid pH sensitive (lipid 2). Lipid 1 is a cationic lipid of permanent charge carried by an N-methylimidazolium group, for the complexation of nucleic acids. Lipid 2 has protonable acidic pH which promotes endosomal escape after destabilization of the membrane in acidic medium. In these lipids it is not a quaternary ammonium but a phosphorus atom which is the link between the carbon chains and the imidazole nucleus. These lipids are lipophosphoramidates whose structure is inspired by those of lipid membranes which are less toxic both in vitro and in vivo.

Liposomes 100 have in particular been described in Perche et al. 2010, Perche et al. 2011, Mevel et al. 2008a, and Mevel et al. 2008b.

Mouse dendritic cells were incubated for 20 hours with these liposomes, or with RNA synthetically produced in vitro as a control. The results are illustrated in FIG. 6B. RNA synthetically produced in vitro as a control gives a very low transfection rate of 0 to 1.5%, with a dose of 100 ng mRNA eGFP in vitro (FIG. 6B, left cytogram). On the other hand, after transfection with the liposomes containing T-bodies RNA, 32.77% of the cells express the fluorescent protein (FIG. 6B, right cytogram).

These results illustrate that the ARs produced by the yeast T-bodies of the application can be transfected into a mammalian cell, more particularly into a dendritic cell, and that the protein that these mRNAs encode can be correctly translated into this cell. host cell. These results support the medical, and in particular vaccine, applications of the RNAs produced by these T-bodies (RNA vaccination).

A mass spectrometric study of the chemical modifications present at the biotech model model luciferase messenger RNA as described in Example 1 was carried out after «pull out» of the luciferase mRNA as follows.

A first hybridization step is carried out between 10 μg RNA extracted complexes, granules, pseudo-viral particles and 1 μM of biotinylated single-stranded DNA oligonucleotide, complementary to the bioproduct RNA luciferase sequence (SEQ ID NO: 45 5′-TCCATCTTCCAGCGGATAGAATGGCGCCGGGCCTTTCTTTATGTTTTTGGCGTC TTCCATAAA 3′) in 5× SSC buffer (750 mM sodium chloride and 75 mM trisodium citrate (adjusted to pH 7.0 with HCl) in a final volume of 100 μL. The reaction volume is incubated for 3 min at 90° C., then 10 mM at 65° C. The hybridization reaction is then stored at room temperature. In parallel, MyOneT1 Dynabeads magnetic beads grafted with streptavidin are washed. 100 μL of beads are collected by pipetting and vortexed at half speed. To separate the beads from the supernatant the beads are centrifuged briefly, then placed on a magnetic medium for 2 mM, the supernatant is removed gently (still tube on the magnetic medium).

The beads are resuspended in an equal volume of B & W IX buffer (5 mM Tris-HCl (pH 7.5) 0.5 mM EDTA 1 M NaCl). This step is repeated 3 times. A last wash is carried out in 5×SSC buffer. The hybridization reaction is placed in the presence of vortex-blended beads at half speed and stirred (600 rpm) for 30 min at 25° C. The beads are washed once in 50 of 1×SSC buffer and 3 times in 25 μL of 0.1×SSC. The supernatant is removed and the beads are resuspended in MilliQ water. The beads are heated at 75° C. for 3 min. The beads are centrifuged briefly, then placed on a magnetic support for 2 mM, the supernatant is collected (still on the magnetic medium) and transferred to a new tube. During the elution step, part of the immobilized oligonucleotide is cleaved from the beads, it can be removed by digestion with DNasel (RNase-free, 3.5 μg/μL final) for 2 hours at 37° C. The sample can be stored at −20° C. The volume of the sample is reduced to 180 μL with MiliQ water, 18 μl, 3 M sodium acetate solution and 2 μL of glycogen (10 mg/mL) are added and vortexed. 600 μL of 100% ethanol are added.

The reaction is vortexed and incubated at −20° C. for at least 1 hour. The reaction is then centrifuged at 10,000 g for 30 min at 4° C. The pellet is rinsed twice with 200 μL of 70% ethanol and then dried at ambient temperature for 5 minutes. The pellet is then taken up in MiliQ water.

A mass spectrometry study of the chemical modifications present at the level of the RNA messenger bioproduced was carried out on this sample. This technique is based on a mass spectrometric analysis (LC-MS) of the fragments obtained after complete hydrolysis by R ase T1 of the RNA studied. 1 μg of RNA is digested into nucleosides and the internal standard (SILIS) is added.

50 ng of each of the RNAs was vectorized using Lipofectamine Messenger Max and luciferase activity in the transfected cells was measured in vitro. It is observed that the bioproduced RNA luciferase in yeast T-bodies (TB) is more efficient (3 logs difference) than the most effective RNA synthesized in vitro (cf. FIG. 9).