NZ520270A

NZ520270A - DNA vaccines optimised by the addition of GM-CSF for protection against farm pathogens

Info

Publication number: NZ520270A
Application number: NZ520270A
Authority: NZ
Inventors: Jean-Christophe Franc Audonnet; Laurent Bernard Fischer; Simona Barzu-Le-Roux
Original assignee: Merial Sas
Priority date: 2000-01-21
Filing date: 2001-01-19
Publication date: 2004-08-27
Also published as: CN101554480A; DK1248650T3; EP1248650A2; CA2398229C; BRPI0107767B1; HUP0203974A3; AU3556601A; PT1248650E; BR0107767A; AR027926A1; EP1248650B1; WO2001052888A3; HUP0203974A2; CN1404398A; ES2277913T3; FR2804028A1; CN1404398B; CA2398229A1; KR100820893B1; DE60124862D1

Abstract

DNA vaccines against a pathogen affecting production-type animals are described, in particular cattle and swine. The vaccines comprise a plasmid containing a nucleotide sequence coding for an immunogen of a pathogen of the animal species concerned, in conditions enabling the in vivo expression of the nucleotide sequence, and a cationic lipid containing a quaternary ammonium salt, of formula (I) wherein: R1 is a linear aliphatic radical, saturated or unsaturated, having 12 to 18 carbon atoms; R2 is another aliphatic radical, containing 2 or 3 carbon atoms; and X is a hydroxyl or amine group. The lipid is preferably DMRIE (N-(2-hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1-propanammonium.

Description

<div class="application article clearfix" id="description"> 5202 70 IMPROVED DNA VACCINES FOR PRODUCTION-TYPE ANIMALS The present invention relates to improved DNA vaccines for farm animals, in particular bovines and porcines. The use of deoxyribonucleic acid (DNA) 5 molecules for vaccination has ' been known since the beginning of the 1990s (Wolf et al. Science 199 0. 247. 1465-1468). This vaccination technique induces cellular and humoral immunity after in vivo transfection of cells of the subject to be vaccinated with DNA or RNA 10 molecules encoding immunologically active proteins. A DNA vaccine is composed of at least one plasmid which may be expressed by the cellular machinery of the subject to be vaccinated and of a pharmaceutically. acceptable vehicle or excipient. The 15 nucleotide sequence of this plasmid encodes, inter alia, one or more immunogens, such as proteins or glycoproteins capable of inducing, in the subject to be vaccinated, a cellular immune respor.se (mobilization of the T lymphocytes). and a humoral immune response 20 (stimulation of the production of antibodies specifically directed against the immunogen) (Davis H.L. Current Opinion Biotech. 1997. 8. 635-640). All the immunogens derived from a pathogen are not antigens which are naturally sufficiently effective 25 for inducing an optimum protective immune response in the animal to be vaccinated. It is therefore necessary to improve the immune response. Various routes of administration of the DNA vaccine have been proposed (intraperitoneal, 3 0 intravenous, intramuscular, subcutaneous, intradermal, mucosal, and the like). Various means of administration have also been proposed, in particular gold particles coated with DNA and projected so as to penetrate into the cells of the skin of the subject to be vaccinated 35 '(Tang et al. Nature 1992. 355. 152-154) and the liquid jet injectors which make it possible to transfeet both skin cells and cells of the underlying tissues (Furth et al. Analytical Bioch. 1992. 205. 365-368). intellectual property OFFICE OF N.Z. - 5 JUL 20M received - 2 - Chemical compounds have been used for the in vitro transfeetion of DNA: A/ - cationic lipids. The cationic lipids are themselves divided into 5 four subgroups. 1) The cationic lipids containing quaternary ammonium salts, such as for example DOTMA (dioleoyl-oxypropyltrimethylammonium, produced by Gibco under the name Lipofectine), DOTAP (trimethyl-2,3-(octadec- 10 9-eneoyloxy)-1-propaneammonium; Gregoriadis et al. FEBS Letters 1997. 402. 107-110), DMRIE (N-(2-hydroxyethyl)-N, N-dimethyl-2,3-bis(tetradecyloxy)-1-propaneammonium; W0-A-9634109), DLRIE (N-(2-hydroxyethyl)-N,N-dimethyl-2 , 3-bis (dodecyloxy)-1-propaneammonium; Feigner et al. 15 Ann. N Y Acad. Sci. 1995. 772. 126-139). These cationic lipids containing quaternary ammonium salts may be combined or otherwise with an additional neutral lipid, such . as DOPC (dioleoyl-phosphatidylcholine) or DOPE (dioleoylphosphatidyl-20 ethanolamine) (J.P.. Behr, Biocoiijugate Chemistry 1994. 5 . 382-389) . 2) The lipoamines, such as for example DOGS (dioctadecylamidoglycylspermine, produced by Promega under the name Transfectam; Abdallah et al. Biol. Cell. 25 1995. 85. 1-7), DC-Choi (dimethylaminoethane-carbamoyl-cholesterol; Gao and Huang, Biochem. Biophys. Res. Commun. 1991. 179. 280-285), BGSC (bis-guanidine-spermidine-cholesterol), BGTC (bis-guanidine-tren-cholesterol) (Vigneron et al. Proc. Natl. Acad. Sci. 30 USA 1996. 93. 9682-9686). 3) The cationic lipids containing quaternary ammonium salts and lipoamines, such as for example DOSPA (N, N-dimethyl-N-(2-(sperminecarboxamido) ethyl) -2,3-bis(dioleoyloxy)-1-propaneimidium pentahydro- 35 chloride, marketed by Gibco under the name Lipof ectAmine®; Hawley-Nelson et a 1. Focus 1993. 15. 73-79), GAP-DLRIE (N-(3-aminopropyl)-N,N-dimethyl-2 , 3-bis (dodecyloxy)-1-propaneammonium; Wheeler et al. Proc. Natl. Acad. Sci. USA 1996. 93. 11454-11459; Norman et al. Vaccine 1997. 15. 801-803). 4) The lipids containing amidine salts, such as for example ADPDE, ADODE (Ruysschaert et al. Biochem. Biophys. Res. Commun. 1994. 203. 1622-1628). B/ - the polymers, such as for example SuperFect™- (molecules of activated dendrimers, produced by Qiagen; Xu et al. Mol. Genet. Metab. 1998. 64. 193-197), and C/ - the biochemical agents, such as for example toxins,.in particular cholera toxins. Some of these compounds have. also been used in the formulation of DNA vaccines with more than mitigated results. Knowledge in the field of in vitro transfection is not transposable to DNA vaccination where the final objective is to ensure a protective immune reaction. Negative effects on the induction of an effective immune protection have even been observed with compounds known to promote transfection in vitro. Some formulation chemical compounds are toxic at high doses for the transfected cells. In the work by Etchart (Etchart et al. J. Gen. Virol. 1997. 78. 1577-1580), the use of DOTAP did not have an. adjuvant effect during the administration of the DNA vaccine by the intranasal route, whereas it had an adjuvant effect by the oral route. DOTAP has also been used in DNA vaccines encoding the influenza virus hemagglutinin (HA) on the mouse model which were administered by the intranasal route (Ban et al. Vaccine 1997. 15. 811-813), but the addition of DOTAP inhibited the immune response. The use of DC-Choi or of DOTAP/DOPE in DNA vaccines encoding the hepatitis B virus surface protein (S) on the mouse model which were administered by the intramuscular route made it possible to increase the antibody response, whereas the use of Lipofectine (or DOTMA) did not increase this response (Gregoriadis et al. FEBS Letters 1997. 402. 107-110) . DC-Chol/DOPE has also been used in DNA vaccines against the human immunodeficiency virus (HIV, _ 4 - Env protein) on the mouse model, whose administration by the intramuscular route induced a more effective immune response, whereas the administration by the subcutaneous or intradermal route did not increase it 5 (Ishii et al. AIDS Res. Hum. Retro. 1997, 13. 1421-1428) . The addition of certain cytokines, in particular interleukins or interferons, can make it possible to enhance the immune response induced in 10 particular by DNA vaccines. Each cytokine triggers a reaction which is specific to it and orients the immune response to a greater or lesser .degree towards a cellular response or towards a . humoral response (Pasquini et al. Immunol. Cell. Biol. 1997. 75. 397-15 401; Kim et al. J. Interferon Cytokine Res. 1999. 19. 77-84). The adjuvant effects of a cytokine obtained from a given species are not necessarily the same if the immune context varies, in particular if this cytokine is administered to another species, therefore 20 in a heterologous immune system. The addition of cytokine may also have no adjuvant effect, or may even result in a reversal of the effect sought, that is to say a reduction or an inhibition of the immune response. Thus, a DNA vaccine encoding a single chain 25 of an immunoglobulin fused with GM-CSF does not increase the immune response, whereas direct administration of this fusion protein to mice is effective, in the same way as is the administration of a fusion protein consisting of Fv and of the cytokine 3 0 IL-Ibeta or the administration of a DNA vaccine "encoding the latter fusion protein (Hakim et al. J. Immunol. 1996. 157. 5503-5511). The use of plasmids co-expressing the cytokine IL-2 and the hepatitis B virus envelope .protein in a fused or nonfused conformation 3 5 results in an increase in the humoral and cellular immune responses (Chow et al. J. Virol. 1997. 71. 169-78). However, the use of a bicistronic plasmid encoding the human acquired . immunodeficiency virus (HIV-1) glycoprotein gpl2 0 and the cytokine IL-2 induced a - 5 - lower specific anti-gpl20 immune response than that obtained by the use of a monocistronic plasmid encoding only gpl20 (Barouch et al. J. Immunol 1998. 161. 1875-1882). The co-injection, into mice, of two expression 5 vectors, one coding for the rabies virus G glycoprotein, the other for murine GM-CSF stimulates the activity of the B and T lymphocytes, whereas .the co-injection with a plasmid encoding gamma-interferon (in place of murine GM-CSF) results in a decrease in 10 the immune response (Xiang et al. Immunity 1995. 2. 129-135) . Certain modifications in the . antigens, such as deletions of part of the nucleotide sequence encoding the antigen, insertions of a DNA fragment into the 15 nucleotide sequence encoding the antigen or into non-translated regions upstream or downstream, can also enhance the efficacy of DNA vaccines, in particular by enhancing the level of expression of the antigen or its presentation. 20 However, in practice, manipulations on the nucleotide sequence encoding the antigen may bring about a reduction or loss of the initial immunological activity. Thus, the deletion of the transmembrane domain from the gene encoding the rabies virus G 25 antigen reduced the level of protection induced in the mouse model after administration by the intramuscular route of a DNA vaccine encoding this modified antigen (Xiang et al. Virol. 1995. 209. 5 69) . The deletion of the . transmembrane domain from the gene encoding the 3 0 bovine herpesvirus (BHV) gD glycoprotein did not make it possible to increase the antibody response and induced only a partial protection in bovines vaccinated by the intramuscular route (van Drunen Little-van den Hurk et al. J. Gen. Virol. 1998. 79. 831-839). The 35 humoral and cellular immune responses and the protection conferred are identical in guinea pigs challenged after having been immunized with the. aid of either a DNA vaccine encoding the Ebola virus GP glycoprotein, or of a DNA vaccine encoding this GP - 6 - glycoprotein but in a secreted form (Xu et al. Nature Medicine 1998. 4. 37-42). The insertion of the signal sequence of the human tissue plasminogen activator (tPA) into the gene 5 encoding the malaria Pf332 antigen did not make it possible to increase the antibody response in mice vaccinated by the intramuscular route (Haddad et al. FEMS 1997. 18. 193-202) . The addition, in phase, of a tPA sequence to the gene encoding the murine rotavirus 10 VP7 antigen also did not make it possible to increase the antibody response in mice vaccinated by the intradermal route., whereas the .. fusion protein consisting of the VP4 antigen and tPA allowed this increase, but without inducing an effective protection 15 (Choi et al. Virology 1998. 250. 230-240) . The modifications carried out on the nucleotide sequence of one antigen cannot in general be directly transposed to another antigen, because antigens do not always have the same structural arrangements. 20 The applicant has as objective the enhancement of the efficacy of DNA vaccination. Its objective is in particular to obtain a better immune response and in particular an effective protection in farm animals, in particular bovines and porcines, by DNA vaccinations. 25 The applicant has as objective the production of improved DNA vaccines which induce an effective and protective immune response against the bovine herpesvirus type 1 (BHV-1) also called infectious bovine rhinotrachitis (IBR) , the bovine respiratory 3 0 syncitial virus (BRSV), the mucosal disease virus or bovine pestivirus type 1 or type 2 (bovine viral diarrhea virus or BVDV-1 and BVDV-2), the parainfluenza virus type 3 (bPI-3) in bovines. The applicant has as objective the production 3 5 of improved DNA vaccines which induce an effective and protective immune response comprising at least one valency selected from the group consisting of porcine herpesvirus or Aujeszky's disease (pseudorabies virus or PRV), the porcine reproductive respiratory syndrome - 7 - virus (or PRRSV), the swine influenza virus (or SIV), the conventional hog cholera virus (or HCV) , parvoviruses in porcines. The applicant also has as objective the 5 production of improved DNA vaccines which make it possible to obtain effective and protective immune protection in bovines, comprising at least one valency selected from the group consisting of the BHV-1, BRSV, BVDV, bPI-3 and rabies viruses. 10 The subject of the invention is improved DNA vaccines which make it possible to obtain effective protection against at least one pathogen which infects farm, in particular bovines and porcines. The DNA vaccine is improved: either by its formulation, or by 15 the addition of GM-CSF, or by the optimization of the antigen(s), or by combinations of these solutions. Preferably, the DNA vaccine is improved by its formulation, and optionally either by the addition of GM-CSF, or by the optimization of the antigen(s), or 20 finally by the addition of GM-CSF and by the optimization of the antigen(s). By definition, the DNA vaccine comprises, as active ingredient, a plasmid encoding and expressing a gene or. gene fragment e.g. epitope. The term plasmid 25 covers a DNA transcription unit comprising a polynucleotide sequence comprising the sequence of the gene to be expressed and the elements necessary for its expression in vivo. The circular plasmid form, supercoiled or otherwise, is preferred. The linear form 3 0 also falls within the scope of this invention. Each plasmid comprises a promoter capable of ensuring, in the host cells,, the expression of the gene inserted under its control. It is in general a strong eukaryotic promoter and in particular a cytomegalovirus 3 5 early promoter CMV-IE, of human or murine origin, or optionally of other origin such as rat or guinea pig. More generally, the promoter is either of viral origin or of cellular origin. As a viral promoter other than CMV-IE, there may be mentioned the SV40 virus early or - 8 - late promoter or the Rous Sarcoma virus LTR promoter. It may also be a promoter the virus from which the gene is derived, for example the promoter specific to the gene. As cellular promoter, there may be mentioned the 5 promoter of a cytoskeleton gene, such as for example the desmin promoter, or alternatively the actin promoter. When several genes are present in the same plasmid, they may be provided in the same transcription unit or in several different units. 10 According to a first mode, the DNA vaccines according to the invention are formulated by adding, as adjuvant, cationic lipids containing a quaternary ammonium salt of formula: CH3 R1 - O - CH2 - CH - CH2 - N — R2 - X 15 0Ri ch3 in which Ri is a saturated or unsaturated linear aliphatic radical having 12 to 18 carbon atoms, R2 is another aliphatic radical containing 2 or 3 20 carbon atoms, and X a hydroxyl or amine group. Preferably, this is DMRIE (N-(2-hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1-propanammonium ; W0-A-9634109) , preferably combined with a neutral lipid, in particular, DOPE (dioleoyl-phosphatidyl-25 ethanolamine), to form DMRIE-DOPE. The subject of the present invention is therefore a DNA vaccine against at least one pathogen affecting farm animals, in particular bovines or porcines, comprising at least one plasmid containing at 30 least- one nucleotide sequence encoding an immunogen of a pathogen of the animal species considered, under conditions allowing the in vivo expression of this sequence, and a cationic lipid containing a quaternary ammonium salt, in particular DMRIE, preferably combined 3 5 with DOPE. - 9 - i Preferably, the recombinant vector is mixed with this adjuvant immediately before use and it is preferable, before its administration to the animal, to allow the mixture thus prepared to form a complex, for 5 example for a period ranging from 10 to 60 minutes, in particular of the order of 30 minutes. When DOPE is present, the DMRIE .-DOPE molar ratio preferably ranges from 95:5 to 5:95, and is more particularly 1:1. 10 The plasmid:DMRIE or DMRIE-DOPE adjuvant weight ratio may range in particular from 50:1 to 1:10, in particular from 10:1 to 1:5, preferably from 1:1 to 1:2. According to a second mode, GM-CSF (granulocyte 15 macrophage-colony stimulating factor; Clark S.C. et al. Science 1987. 230. 1229; Grant S.M. et al. Drugs 1992. 53. 516) is added to the vaccines according to the invention; this may be carried out by incorporating GM-CSF protein directly into the vaccinal composition 2 0 or preferably by inserting the nucleotide sequence encoding GM-CSF into an expression vector under conditions allowing its expression in vivo. As expression vector, the use of a plasmid, e.g. the plasmid containing the nucleotide sequence encoding the 25 antigen(s) of interest or another plasmid, is preferred. The choice of GM-CSF is preferably made according to the animal species to be vaccinated; thus, for bovines, bovine GM-CSF is used; for pigs, it is porcine GM-CSF. 3 0 According to a third mode, the nucleotide sequence(s) encoding the immunogen are in an optimized form. Optimization is understood to mean any modification of the nucleotide sequence, in particular which .manifests itself at least by a higher level of 35 expression of this nucleotide sequence, and/or by an increase in the stability of the messenger RNA encoding this antigen, and/or by the triggered secretion of this antigen into the extracellular medium, and having as - 10 - direct or indirect consequence an increase in the immune response induced. In the present invention, the optimization of the antigen of interest preferably consists in the 5 deletion of the fragment of the nucleotide sequence encoding the transmembrane domain of the antigen of interest (deletion is understood to mean the complete deletion or a partial deletion sufficient for the transmembrane domain to no longer, or no longer 10 substantially, be functional), and/or in the addition, in frame, of a nucleotide sequence encoding the tPA (Montgomery et al. Cell. Mol. Biol. 1.997. 43. 285-292; Harris et al. Mol. Biol. Med 1986. 3. 279-292) signal, and/or in the insertion of a stabilizing intron 15 upstream of the gene to be expressed. The deletion of the DNA fragment encoding the transmembrane domain of the antigen of interest promotes the secretion, into the extracellular medium, of the antigens thus truncated and thus increases the possibilities of their 20 coming into contact with the cells of the immune system. The insertion of the nucleotide sequence encoding the tPA signal facilitates the translatability of the messenger RNA to which the tPA signal is joined, and thus increases the level of expression of this 25 messenger RNA and therefore the production of antigens. The tPA signal also plays a role in the secretion of the antigen synthesized. Other nucleotide sequences, encoding signal peptides may be used, in particular those for the 3 0 signal peptide of melittin obtained from bees (Sisk W.P. et al., 1994, J. Virol., 68, 766-775). The insertion of a stabilizing intron into the gene encoding the antigen of interest avoids the aberrant splicings of its messenger RNA and maintains 35 the physical integrity of the latter. Preferably, the tPA signal is of human origin. The nucleotide sequence of the human tPA signal is accessible from the GenBank database under the accession number NM_000930. Preferably, the intron is - 11 - intron II of the rabbit beta-globin gene (van Ooyen et al. Science 1979. 206. 337-344), whose nucleotide sequence is accessible from the GenBank database under the accession number V00882 and designated by a 5 reference under intron No. 2. The subject of the present invention is an improved DNA vaccine capable of inducing an effective and protective immune response in bovines against infectious bovine rhinotrachitis (IBR). 10 The virus responsible for infectious bovine rhinotrachitis is a bovine herpesvirus type 1 (BHV-1), a member of the Alphaherpesvirinae family (Babiuk L.A. et al., 1996, Vet. Microbiol., 53, 31-42). Nucleotide sequences encoding the glycoproteins gB, gC and gD are 15 known and are accessible from the GenBank database under the accession number AJ004801. According to the invention, the DNA vaccine against IBR is preferably improved by its formulation with an adjuvant according to the invention, in 20 particular DMRIE, preferably DMRIE-DOPE. Optionally, this may be combined either with the addition of bovine GM-CSF (Maliszewski et al. , Molec. Immunol., 1988, 25, 843-850) , or the optimization of at least one IBR antigen, or finally the addition of bovine GM-CSF and 25 the optimization of at least one IBR antigen. A nucleotide sequence encoding bovine GM-CSF is accessible from the GenBank database under the accession number U22385. The addition of bovine GM-CSF may be carried 3 0 out by the incorporation of the bovine GM-CSF polypeptide into the vaccinal composition or preferably by the insertion of the nucleotide sequence encoding the bovine GM-CSF into an in vivo expression vector, preferably a plasmid. Preferably, the nucleotide 35 sequence encoding bovine GM-CSF is inserted into a second expression plasmid (e.g. pLF1032 Example 13), different from that (or those) into which the gene(s) encoding the IBR antigen(s) is(are) inserted. - 12 - The optimization of the antigens derived from IBR is carried out by substitution, by a "signal" sequence, in particular that of the tPA signal of human origin (GenBank accession number NM_000930) , of the 5 sequence of the signal peptide of the glycoprotein gB and/or of the glycoprotein gC and/or of the glycoprotein gD, and/or by the deletion of the DNA fragment encoding the transmembrane domain of gB and/or of gC and/or of gD. The deletion of the DNA fragment 10. encoding the transmembrane domain of one of these glycoproteins is preferably accompanied by the contiguous C-terminal part (cytoplasmic portion of the glycoprotein). The DNA vaccine against IBR according to the invention can therefore encode and express a single 15 optimized IBR antigen (gB, gC or gD) or two of them or all three, that is to say optimized gB, optimized gC and optimized gD. Nucleotide sequences encoding the BHV-1 antigens which can be used in the present invention and 2 0 various constructs of expression vectors are given in the accompanying examples and in FR-A1-2751229, in particular in Examples 7 and 8, and in Figures 3 and 4. Preferably, according to the invention, the DNA vaccine .against BHV-1 is formulated with DMRIE-DOPE, 25 and is composed of an expression plasmid (e.g. pPB281, Example 3.1.2) encoding the BHV-1 gB antigen optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part, of a second expression 3 0 plasmid (e.g. pPB292, Example 3.2.2) encoding the BHV-1 gC antigen optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part, and of a third, expression plasmid (e.g. pPB284, Example 3.3.2) 3 5 encoding the BHV-1 gD antigen optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part. - 13 - In general, and not only for BHV-1, the C-terminal part contiguous to the sequence encoding the transmembrane domain may be conserved. It is however often easier to delete it at the same time as the 5 sequence encoding the transmembrane domain. The subject of the present invention is also an improved DNA vaccine capable of inducing an effective and protective immune response in bovines against the bovine respiratory syncitial virus (BRSV). 10 The BRSV virus is a Paramyxovirus, also a member of the Paramyxoviridae family (Baker efc al. , Vet. Clin. North Am. Food Anim. Pract., 1997, 13, 425-454). Nucleotide sequences encoding the F protein and the G glycoprotein are known and accessible from 15 the GenBank database respectively under the accession number Y1797 0 and U33539. The DNA vaccine against BRSV is preferably formulated with an adjuvant according to the invention, in particular DMRIE, preferably DMRIE-DOPE. This may be 2 0 optionally combined with either the addition of bovine GM-CSF, or the optimization of at least one BRSV antigen, or finally the addition of bovine GM-CSF and the optimization of at least one BRSV antigen. The addition of bovine GM-CSF may be carried 25 out as is described for BHV-1. The optimization of the antigens derived from BRSV is carried out by substitution, by a "signal" sequence, in particular that of the tPA of human origin, of the signal sequence of the F protein of BRSV 3 0 and/or of the G envelope glycoprotein of BRSV, and/or by the deletion of the DNA fragment encoding the transmembrane domain of F and/or of G. The deletion of the DNA fragment encoding the transmembrane domain of one of these proteins is preferably accompanied by the 3 5 contiguous C-terminal part. The DNA vaccine against BRSV according to the invention can therefore encode and express a single optimized BRSV antigen (F or G) or both (F and G). - 14 - A. Nucleotide sequences encoding the BRSV antigens which can be used in the present invention and various expression vector constructs are given in the accompanying examples and in FR-Al-2751229, in 5 particular in Examples 9 and 10, and in Figures 5 and 6. Preferably, according to the invention, the DNA vaccine against BRSV is formulated with DMRIE-DOPE, and is composed of an expression plasmid (e.g. pSB114 10 Example 4.1.3) encoding the F antigen of BRSV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of F, by the deletion of the fragment of the nucleotide sequence of F encoding the transmembrane domain and the contiguous 15 C-terminal part, and of a second expression plasmid (e.g. pSBllO Example 4.2.2) encoding the G antigen of BRSV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of G, by the deletion of the fragment of the nucleotide 20 sequence encoding the transmembrane domain of G and the contiguous C-terminal part. The subject of the present invention is also an improved DNA vaccine capable of inducing an effective and protective immune response in bovines against the 25 BVDV virus. The BVDV virus is a pestivirus of the Flaviviridae family. It is universally distributed in bovine populations and manifests itself by fetal malformations, abortions or clinical respiratory 3 0 (mucosal disease) and enteric (bovine viral diarrhea) symptoms. The BVDV viruses are distinguishable by the seriousness of the clinical signs and two groups have been formed, the BVDVs type 1 (inapparent or mild 35 clinical signs) and those of type 2 (acute clinical signs, hemorrhage, high morbidity, high mortality) (Dean H.J. and Leyh R., 1999, Vaccine, 17, 1117-1124). - 15 - When a BVDV virus type is not clearly specified, this virus is understood to be type 1 or type 2. The BVDV virus is an enveloped single-stranded 5 RNA virus composed of a single gene encoding a polyprotein which, after cleavage, gives several well-individualized proteins, in particular the EO protein (gp48) and the E2 protein (gp53) (Vassilev V.B. et al., 1997, J. Virol., 71, 471-478). 10 Nucleotide sequences encoding the E0-E2 polyproteins are known and accessible from the GenBank database under the accession number M96687 for BVDV-1 and AF145967 for BVDV-2. The DNA vaccine against BVDV is preferably 15 formulated with an adjuvant according to the invention, in particular DMRIE, preferably DMRIE-DOPE. This may be optionally combined with either the addition of bovine GM-CSF, or the optimization of at least one BVDV antigen, or finally the addition of bovine GM-CSF and 2 0 the optimization of at least one BVDV antigen. The addition of bovine GM-CSF may be carried out as is described for BHV-1. The optimization of the antigens derived from BVDV is- carried out by the addition of a "signal" 25 . sequence, in particular that of the tPA of human origin, upstream of the nucleotide sequence encoding the EO protein of BVDV and/or of the E2 protein of BVDV, and/or by the deletion of the DNA fragment encoding the transmembrane domain of E2, and/or by the 3 0 insertion of an intron, in particular intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding EO and/or E2. The DNA vaccine against BVDV according to the invention may therefore encode and express a single optimized BVDV antigen (EO or E2) 35 or both (EO and E2) . Nucleotide sequences encoding the BVDV antigens which can be used in the present invention and various constructs of expression vectors are given in the - 16 - accompanying examples and in FR-Al-27 51229, in particular in Example 13, and in Figure 9. Preferably, according to the invention, the DNA vaccine against BVDV is formulated with DMRIE-DOPE, and 5 is composed of an expression plasmid (e.g. pLF1029 Example 5.1.2, pLFl031 Example 6.2.2) encoding the EO antigen of BVDV optimized by the insertion of the signal sequence of the human tPA upstream of EO and by the insertion of intron II of the rabbit beta-globin 10 gene upstream of EO, and of a second expression plasmid (e.g. pLFl021 Example 5.2.2, pLF1023 Example 6.1.2) encoding the E2 antigen of BVDV optimized by the insertion of the signal sequence of the human tPA upstream of E2, by the deletion of the fragment of the 15 nucleotide sequence .encoding the transmembrane domain of E2 and the contiguous C-terminal part and by the insertion of intron II of the rabbit beta-globin gene upstream of E2 . A mixture of plasmids can be advantageously 20 produced. The mixture may comprise at least two expression plasmids, each expressing a different immunogen (EO or E2) and/or obtained from a different type of BVDV (BVDV-1 or BVDV-2) . In particular, a mixture made of four plasmids expressing BVDV-1 EO, 25 BVDV-1 E2, BVDV-2 EO and BVDV-2 E2. The subject of the present invention is also an improved DNA vaccine capable of inducing an effective and protective immune response in bovines against the parainfluenza virus type 3 (bPI-3). 3 0 The bPI-3 virus is a Paramyxovirus, also a member of the Paramyxoviridae family (Tsai et al. , Infect. Immun. , 1975, 11, 783-803)'. Nucleotide sequences encoding the hemagglutinin and neuraminidase proteins (HN) and the fusion protein 35 (F) of bPI-3 are known and accessible from the GenBank database under the accession number U31671. The DNA vaccine against bPI-3 is preferably formulated with an adjuvant according to the invention, in particular DMRIE, preferably DMRIE-DOPE. This may be - 17 - optionally combined with either the addition of bovine GM-CSF, or the optimization of at least one bPI-3 antigen, of finally the addition of bovine GM-CSF and the optimization of at least one bPI-3 antigen. 5 The addition of bovine GM-CSF may be carried out as is described for BHV-1. The optimization of the antigens derived from bPI-3 is carried out by substitution, by a "signal" sequence, in particular that of the tPA of human 10 origin, of the signal sequence of hemagglutinin-neuraminidase (HN) of bPI-3 and/or of the fusion protein (F) of bPI-3, and/or by the deletion of the DNA fragment encoding the transmembrane domain of HN and/or of F, and/or by the insertion of an intron, in 15 particular of intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding HN and/or F. The deletion of the DNA fragment encoding the transmembrane domain of one of these proteins is preferably accompanied by the contiguous C-terminal 20 part. The DNA vaccine against bPI-3 according to the invention may therefore encode and express a single optimized PI-3 antigen (HN or F) or both (HN and F) . Nucleotide sequences encoding the bPI-3 antigens, which can be used in the present invention and 25 various expression vector constructs are given in the accompanying examples and in FR-Al-2751229, in particular in Examples 14 and 15, and in Figures 10 and 11. Preferably, according to the invention, the DNA 3 0 vaccine against bPI-3 is formulated with DMRIE-DOPE, and is composed of an expression plasmid (e.g. pLF1025 Example 7.1.2) encoding the HN antigen of bPI-3 optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of HN, by 3 5 the deletion of the fragment of the nucleotide sequence of HN encoding the transmembrane domain and the contiguous C-terminal part and by the insertion of intron II of the rabbit beta-globin gene upstream of HN, and of a second expression plasmid (e.g. pLF1027 - 18 - Example 7.2.2) encoding the F antigen of bPI-3 optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of F, by the deletion of the fragment of the nucleotide sequence 5 encoding the transmembrane domain of F and the contiguous C-terminal part and by the insertion of intron II of the rabbit beta-globin gene upstream of F. The subject of the present invention is an improved DNA vaccine capable of inducing an effective 10 and protective immune response in pigs against porcine herpesvirus (PRV). The PRV virus is a .member of the Alphaherpesvirinae family, this virus is responsible for Aujeszky's disease (Sawitzky D., Arch. Virol. 15 Suppl., 1997, 13, 201-206). Nucleotide sequences encoding the glycoproteins gB, gC and gD are known and accessible from the GenBank database under the accession number M17321, AF158090, AF 0 8 6 7 0 2 . 20 ■ The DNA vaccine against PRV is preferably formulated with an adjuvant according to the invention, in particular DMRIE, preferably DMRIE-DOPE. This may be optionally combined with either the addition of porcine GM-CSF (Inumaru S. and Takamatsu H. , Immunol. Cell. 25 Biol., 1995, 73, 474-476), or the optimization of at least one PRV antigen, or finally the addition of porcine GM-CSF and the optimization of at least one PRV antigen. The addition of porcine GM-CSF may be carried 3 0 out by the incorporation of the porcine GM-CSF polypeptide into the vaccine composition or by the insertion of a nucleotide sequence encoding the porcine GM-CSF (e.g. accessible from the GenBank database under the accession number D21074) into an in vivo expression 35 vector, preferably a plasmid. Preferably, the nucleotide sequence encoding porcine GM-CSF is inserted into a second expression plasmid (e.g. pLFl033 Example 14), different from that (or those) into which - 19 - the gene(s) encoding the PRV antigen(s) is (are) inserted. The optimization of the antigens derived from PRV is carried out by substitution, by a "signal" 5 sequence, in particular that of the tPA signal of human origin (GenBank accession number NM_000930), of the sequence of the signal peptide of the glycoprotein gB and/or of the glycoprotein gC and/or of the glycoprotein gD, and/or by the deletion of the DNA 10 fragment encoding the transmembrane domain of gB and/or of gC and/or of gD. The deletion of the DNA fragment encoding the transmembrane domain -of one of these glycoproteins is preferably accompanied by the contiguous C-terminal part. The DNA vaccine against PRV 15 according to the invention may therefore encode and express a single optimized PRV antigen (gB, gC or gD) or two of them or the three, that is to say optimized gB, optimized gC and optimized gD. Nucleotide sequences encoding the PRV antigens 2 0 which can be used in the present invention and various expression vector constructs are given in the accompanying examples and in FR-A1-27 51224, in particular in Examples 8 and 9 and in Figures 3 and 5. Preferably, according to the invention, the DNA 25 vaccine against PRV is formulated with DMRIE-DOPE, and is composed of an expression plasmid (e.g. pSBl02 Example 8.1.2) encoding the gB antigen of PRV optimized by the deletion of the fragement of the nucleotide sequence encoding the transmembrane domain and of the 30 contiguous C-terminal part, of a second expression plasmid (e.g. pSB104 Example 8.2.2) encoding the gC antigen of PRV optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and of the contiguous C-terminal 35 part, and of a third expression plasmid (e.g. pSBl06 Example 8.3.2) encoding the gD antigen of PRV optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and of the contiguous C-terminal part. - 20 - The subject of the present invention is an improved DNA vaccine capable of inducing an effective and protective immune response in pigs against the porcine reproductive , respiratory syndrome virus 5 (PRRSV). The PRRSV virus is an Arterivirus, a member of the Arteriviridae family, (Murtaugh et al. , Arch. Virol., 1995, 140, 1451-1460). Nucleotide sequences encoding the proteins 10 encoded by the open reading frames 0RF3, 0RF5 and ORF6 are known and accessible from .the GenBank database under the accession number U87392. The DNA vaccine against PRRSV is preferably formulated with an adjuvant according to the invention, 15 in particular DMRIE, preferably DMRIE-DOPE. This may be optionally combined with either the addition of porcine GM-CSF, or the optimization of at least one PRRSV antigen, or finally the addition of porcine GM-CSF and the optimization of at least one PRRSV antigen. 2 0 The addition of porcine GM-CSF may be carried out as is described for PRV. The optimization of the antigens derived, from PRRSV is carried out by substitution, by a "signal" sequence., in particular that of the tPA signal of human 25 origin (GenBank accession number NM_00093 0), of the sequence of the signal peptide of the protein encoded . by the open reading frame 3 (0RF3, gp45 or large envelope glycoprotein) and/or of the glycoprotein ORF5 (gp25 or envelope glycoprotein E) and/or of the 3 0 glycoprotein 0RF6 (gpl8 or membrane protein), and/or by the deletion of the DNA fragment encoding the transmembrane domain of 0RF3 and/or 0RF5 and/or 0RF6. The deletion of the DNA fragment encoding the transmembrane domain of one of these glycoproteins is 35 preferably accompanied by the contiguous C-terminal part. The DNA vaccine against PRRSV according to the invention may therefore encode and express a single optimized PRRSV antigen (ORF3, 0RF5 or 0RF6) or two of - 21 - them or the three, that is to say optimized 0RF3, optimized 0RF5 and optimized 0RF6. Nucleotide sequences encoding the PRRSV antigens which can be used in the present invention and 5 various expression vector constructs are given in the accompanying examples and in FR-Al-2751224, in particular in Examples 14 to 17 and in Figures 14 to 17 . Preferably, according to the invention, the DNA 10 vaccine against PRRSV is formulated with DMRIE-DOPE, and is composed of an expression plasmid (e.g. pLF1009 Example 9.1.1, pLF1015 Example 10.1..1) encoding the ORF3 antigen of PRRSV, of a second expression plasmid (e.g. pLFl012 Example 9.2.2, pLF1018 Example 10.2.2) 15 encoding the ORF5 ' antigen of PRRSV optimized by substitution of the signal sequence of ORF5 by the human tPA signal peptide sequence and by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal 2 0 part, and of a third expression plasmid (e.g. pLF1014 Example 9.3.2, pLFlOlS Example 10.3.2) encoding the ORF6 antigen of PRRSV optimized by the substitution of the signal sequence of ORF6 by the human tPA signal peptide sequence and by the deletion of the fragment of 2 5 the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part. A mixture of plasmids may be advantageously produced. The mixture may comprise at least two expression plasmids, each expressing a different 30 iirtmunogen (ORF3, ORF5 or ORF6) and/or obtained from a different strain of PRRSV (e.g. European strain, for example Lelystad, American strain ATCC VR-2332). In particular, a mixture made of six plasmids expressing PRRSV Lelystad ORF3, PRRSV Lelystad ORF5, PRRSV 35 Lelystad ORF6, PRRSV VR-2332 ORF3, PRRSV VR-2332 ORF5 and PRRSV VR-2332 ORF6. The subject of the present invention is also an improved DNA vaccine capable of inducing an effective - 22 - and protective immune response in porcines against the swine influenza virus (SIV). The SIV virus is an influenza virus group A, a member of the Orthomyxoviridae family (Murphy B.R. and 5 Webster R.G., Virology, Second Edition, edited by B.N. Fields, D.M. Knipe et al. , Raven Press Ltd., New York 1990). Nucleotide sequences encoding the hemagglutinin (HA) and neuraminidase (NA) proteins of the SIV H1N1 10 and H3N2 strains are known and accessible from the GenBank database under the accession number K00992, U86145, U07146, AF153238. The DNA vaccine against SIV is preferably formulated with an adjuvant according to the invention, 15 in particular DMRIE, preferably DMRIE-DOPE. This may be optionally combined with either the addition of porcine GM-CSF, or the optimization of at least one SIV antigen, or finally the addition of porcine GM-CSF and the optimization of at least one SIV antigen. 20 The addition of porcine GM-CSF may be carried out as is described for PRV. The optimization of the antigens derived from SIV is carried out by substitution, by a "signal" sequence, in particular that of the tPA of human 25 origin, of the signal sequence of SIV hemagglutinin (HA) and/or of the SIV neuraminidase (NA) protein, and/or by the deletion of the DNA fragment encoding the transmembrane domain of HA and/or of. NA, and/or by the insertion of an intron, in particular of intron II of 3 0 the rabbit beta-globin gene upstream of the nucleotide sequence encoding HA and/or NA. The deletion of the DNA fragment encoding the transmembrane domain of one of these proteins is preferably accompanied by the contiguous C-terminal part. The DNA vaccine against SIV 3 5 according to the invention may therefore encode and express a single optimized SIV antigen (HA or NA) or both (HA and NA). Nucleotide sequences encoding SIV antigens which can be used in the present invention and various - 23 - expression vector constructs a^e given in the accompanying examples and in FR-A1-2751224, in particular in Examples 10 and 11, and in Figures 7 and 9 for SIV strain HlNl, and in Examples 12 and 13, and 5 in Figures 11 and 13 for SIV strain H3N2. Preferably, according to the invention, the DNA vaccine against SIV is formulated with DMRIE-DOPE, and is composed of an expression plasmid (e.g. pLF1002 Example 11.1.2, pLFlO06 Example 12.1.2) encoding the HA 10 antigen of SIV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of HA, by the deletion of the fragment of the nucleotide sequence of HA encoding the transmembrane domain and the contiguous C-terminal part, and by the 15 insertion of intron II of the rabbit beta-globin gene upstream of HA, and of a second expression plasmid (e.g. pLF1004 Example 11.2.2, pLFlO08 Example 12.2.2) encoding the NA antigen of SIV optimized by the insertion of the signal sequence of the human tPA in 20 place of the signal sequence of NA, by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain of NA and the contiguous C-terminal part, and by the insertion of intron II of the rabbit beta-globin gene upstream of NA. 2 5 A mixture of plasmids may be advantageously produced. The mixture may comprise at least two expression plasmids, each expressing a different immunogen (HA or NA) and/or derived from a different SIV strain (e.g. H1N1 or H3N2). In particular, a 3 0 mixture made of four plasmids expressing SIV H1N1 HA, SIV H1N1 NA, SIV H3N2 HA and SIV H3N2 NA. Although the invention is described in relation to specific DNA vaccines, the invention and in particular the use of the adjuvants according to the 3 5 invention also applies to DNA vaccines directed against other pathogens of these animal species. In the same line of thought, the vaccines according to the invention may be, for an animal species, combined with one another and/or with DNA ', - 24 - vaccines directed against other pathogens of the same species. These other pathogens may be in particular the rabies virus, hog cholera virus and porcine 5 . parvoviruses. An immunogenic preparation or an improved DNA vaccine according to the invention against the rabies virus comprises in particular a plasmid encoding the unmodified G glycoprotein of the rabies virus and 10 DMRIE-DOPE and optionally the addition of-GM-CSF. An improved immunogenic preparation or DNA vaccine according to the invention against the porcine parvovirus comprises in particular a plasmid encoding an antigen derived from the porcine parvovirus (e.g. 15 the VP2 protein, ' Example 18 and Figure 18 of FR-A1-2751224) and DMRIE-DOPE and optionally the addition of porcine GM-CSF (e.g. pLFl033, Example. 14) . An improved immunogenic preparation or DNA vaccine, according to the invention against the hog 2 0 cholera virus (HCV) comprises in particular a plasmid encoding an antigen derived from HCV (e.g. the El protein, Example 19 and Figure 19 of or the E2 protein, Example 20 and Figure 2 0 of the same document) and DMRIE-DOPE and optionally porcine GM-CSF (e.g. pLF1033, 2 5 Example 14). Thus, the subject of the present invention is also improved multivalent DNA vaccines which make it possible to obtain an effective protection in bovines against at least two bovine pathogens selected from the 3 0 group consisting of the BHV-1, BRSV, BVDV, bPI-3 and rabies viruses. The subject of the present invention is also improved multivalent DNA vaccines which make it possible to obtain effective protection in pigs against 35 at least two porcine pathogens selected from the group consisting of the PRV virus, PRRSV virus, SIV virus, hog cholera virus (or HCV), and porcine parvoviruses. The multivalent DNA vaccines may be improved by their formulation with an adjuvant according to the invention, in particular with DMRIE, preferably with DMRIE-DOPE. This may be optionally combined either with the addition of GM-CSF as previously described, or with the optimization of at least one antigen of .interest as previously described, or finally by the addition of GM-CSF and the optimization of at least one antigen of interest. The improved multivalent DNA vaccines according to the invention are composed of one' or more expression plasmids, such that these vaccines lead to the in vivo expression .of at least one immunogen of. a first pathogen and of at: least one immunogen of at least one other pathogen, infecting the same animal species. At least one of these immunogens is preferably selected from the members of the following group: - F of BRSV,. G of BRSV, gB of BHV-1, gC of BHV-1, gD of BHV-1, EO of BVDV-1, E2 of BVDV-1, EO of BVDV-2, E2 of BVDV-2, F of bPI-3 and HN of bPI-3 for bovines, and - gB of PRV, gC of PRV, gD of PRV, 0RF3 of PRRSV strain Lelystad, 0RF5 of PRRSV strain Lelystad, 0RF6 of PRRSV strain Lelystad, 0RF3 of PRRSSV strain VR-2332, 0RF5 of PRRSV strain VR-2332, 0RF6 of PRRSV-strain VR-2332, HA of SIV strain H1N1, NA of SIV strain H1N1,' HA of SIV strain H3N2 and NA of SIV strain H3N2 for porcines. The improved monovalent or multivalent DNA vaccines according to the invention may also be combined with at least one conventional vaccine (inactivated, attenuated live, subunit) or recombinant vaccine using an in vivo expression vector (e.g. poxvirus, adenovirus, herpesvirus.) directed against at least one , different pathogen infecting the same species , or be used as a booster for such vaccines. Persons skilled in the art may refer to FR-Al-2751229 for the methods for constructing the plasmids containing these bovine valencies, to FR-A1-2751224 for the porcine valencies. - 26 - The subject of the present invention is also a method of vaccinating farm animals, in particular bovines or porcines. This vaccination method comprises the administration of one of the monovalent or 5 multivalent improved DNA vaccines as described above. These vaccination methods concern gestating females for the passive transfer of immunity or young animals or adults. This vaccination method comprises the administration of one or more doses of the improved DNA 10 vaccine. The quantity of DNA used in the vaccines according to the present invention -is between about 10 y.g and about 100 0 ug, and preferably between about 5 0 y.g and about 50 0 ]ag, for' a given plasmid. Persons 15 skilled in the art possess the competence necessary to precisely define the effective dose of DNA to be used for each vaccination protocol. The dose volumes may be preferably between 0.2 and 5 ml, preferably between 1-and 3 ml. 2 0 The improved DNA vaccines according to the invention may be administered, in the context of this vaccination method, by various routes of administration proposed in the prior art for polynucleotide vaccination and by means of known techniques of 25 administration. According to a preferred mode of the invention, the methods of vaccination comprise the administration of the improved DNA vaccines according to the invention by the intramuscular route, the subcutaneous route or 3 0 with the aid of an injector without needle by the intradermal route. Unless the context clearly requires otherwise, throughout the description and the claims, the words ''comprise'", ''comprising'" and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, 3 5 that is to say, in the sense of "including, but not limited to'". (Followed by page 26a) intellectual property office OF N.Z. 1 6 JUN 2004 received - 26a - The invention will now be described in greater detail with the aid of embodiments taken as nonlimiting examples and referring to the drawings, in which: Figure No. 1: plasmid pVR10l'2 Figure No. 2: plasmid pABllO Sequence listing: SEO ID NO 1: oligonucleotide PB326 (Followed by page 27) intellectual property OFFICE OF N.Z. 16 JUN 2004 received SEQ ID NO 2 SEQ ID NO 3 SEQ ID NO 4 SEQ ID NO 5 SEQ ID NO 6 SEQ ID NO 7 SEQ ID NO 8 SEQ ID NO 9 - 27 - oligonucleotide PB329 oligonucleotide SB090 oligonucleotide SB091 oligonucleotide LF001 oligonucleotide LF002 oligonucleotide PB234 oligonucleotide PB235 oligonucleotide PB511 SEQ ID NO 10: oligonucleotide PB512 10 SEQ ID NO 11: oligonucleotide SB221 SEQ ID NO 12: oligonucleotide SB222 SEQ ID NO 13: oligonucleotide PB507 SEQ ID NO 14: oligonucleotide PB508 SEQ ID NO 15: oligonucleotide PB513 15 SEQ ID NO 16: oligonucleotide PB514 SEQ ID NO 17: oligonucleotide SB223 SEQ ID NO 18: oligonucleotide SB224 SEQ ID NO 19: oligonucleotide PB497 SEQ ID NO 20: oligonucleotide PB498 20 SEQ ID NO 21: oligonucleotide SB225 SEQ ID NO 22: oligonucleotide SB226 SEQ ID NO 23: oligonucleotide SB210 SEQ ID NO 24: oligonucleotide SB211 SEQ ID NO 25: oligonucleotide SB212 25 SEQ ID NO 26: oligonucleotide SB220 SEQ ID NO 27: oligonucleotide SB213 SEQ ID NO 28: oligonucleotide SB214 SEQ ID NO 29: oligonucleotide SB215 SEQ ID NO 30: oligonucleotide SB216 30 SEQ ID NO 31: oligonucleotide LF050 SEQ ID NO 32: oligonucleotide LF051 SEQ ID NO 33: oligonucleotide LF052 SEQ ID NO 34: oligonucleotide LF053 SEQ ID NO 35: oligonucleotide LF039 35 SEQ ID NO 36: oligonucleotide LF040 SEQ ID NO 37: oligonucleotide LF041 SEQ ID NO 38: oligonucleotide LF042 SEQ ID NO 39: oligonucleotide LF043 SEQ ID NO 40: oligonucleotide LF044 SEQ ID NO 41: oligonucleotide LF045 SEQ ID NO 42: oligonucleotide LF046 SEQ ID. NO 43: oligonucleotide LF064 SEQ ID NO 44: oligonucleotide LF065 SEQ ID NO 45: oligonucleotide LF066 SEQ ID NO 46: oligonucleotide LF067 SEQ ID NO 47: oligonucleotide LF047 SEQ ID NO 48: oligonucleotide LF048 SEQ ID NO 49: oligonucleotide LF058 SEQ ID NO 50: oligonucleotide LF059 SEQ ID NO 51: oligonucleotide LF060 SEQ ID NO 52: oligonucleotide LF061 SEQ ID NO 53: oligonucleotide LF062 SEQ ID NO 54: oligonucleotide LF063 SEQ ID NO 55: oligonucleotide SB201 SEQ ID NO 56: oligonucleotide SB2 02 SEQ ID NO 57: oligonucleotide SB203 SEQ ID NO 58: oligonucleotide SB217 SEQ ID NO 59: oligonucleotide SB204 SEQ ID NO 60: oligonucleotide SB205 SEQ ID NO 61: oligonucleotide SB206 SEQ ID NO 62: oligonucleotide SB218 SEQ ID NO 63: oligonucleotide SB2 07 SEQ ID NO 64: oligonucleotide SB208 SEQ ID NO 65: oligonucleotide SB209 SEQ ID NO 66: oligonucleotide SB219 SEQ ID NO 67: oligonucleotide LF027 SEQ ID NO 68: oligonucleotide LF028 SEQ ID NO 69: oligonucleotide LF019 SEQ ID NO 70: oligonucleotide LF020 SEQ ID NO 71: oligonucleotide LF021 SEQ ID NO 72: oligonucleotide LF022 SEQ ID NO 73: oligonucleotide LF023 SEQ ID NO 74: oligonucleotide LF024 SEQ ID NO 75: oligonucleotide LF025 SEQ ID NO 76: oligonucleotide LF026 SEQ ID NO 77: oligonucleotide LF037 SEQ ID NO 78: oligonucleotide LF038 SEQ ID NO 79: oligonucleotide LF029 - 29 - SEQ ID NO 80 : oligonucleotide LF030 SEQ ID NO 81: oligonucleotide LF031 SEQ ID NO 82 : oligonucleotide LF032 SEQ ID NO 83 : oligonucleotide LF033 5 SEQ ID NO 84 : oligonucleotide LF034 SEQ ID NO 85: oligonucleotide LF035 SEQ ID NO 86: oligonucleotide LF03 6 SEQ ID NO 87 : oligonucleotide LF003 SEQ ID NO 88 : oligonucleotide LF004 10 SEQ ID NO 89 : oligonucleotide LF005 SEQ ID NO 90 : oligonucleotide LF006 SEQ ID NO 91: oligonucleotide LF007 SEQ ID NO 92 : oligonucleotide LF0 08 SEQ ID NO 93 : oligonucleotide LF009 15 SEQ ID NO 94: oligonucleotide LF010 SEQ ID NO 95 : oligonucleotide LF011 SEQ ID NO 96: oligonucleotide LF012 SEQ ID NO 97 : oligonucleotide LF013 SEQ ID NO 98: oligonucleotide LF014 20 SEQ ID NO 99 : oligonucleotide LF015 SEQ ID NO 100 oligonucleotide LF016 SEQ ID NO 101 oligonucleotide LF017 SEQ ID NO 102 oligonucleotide LF018 SEQ ID NO 103 oligonucleotide LF054 25 SEQ ID NO 104 oligonucleotide LF055 SEQ ID NO 105 oligonucleotide LF056 SEQ ID NO 106 oligonucleotide LF057 EXAMPLES: 3 0 For each of the pathogens considered, each gene encoding the principal antigens (native form and modified form) was the subject of a particular construction in a eukaryotic expression plasmid. The secreted forms of the antigens were obtained by 3 5 deletion of the fragments of genes encoding the transmembrane and cytoplasmic domains. In all cases, the transmembrane domains of the proteins were identified on the basis of the hydropathy profiles (on MacVector 6.5) of the corresponding protein sequences. - 30 - Example 1: Molecular biology methods 1.1 Extraction of viral genomic DNA 5 Viral suspensions were treated with proteinase K (100 mg/ml final) in the presence of sodium dodecyl sulphate (SDS) (0.5% final) for 2 hours at 37°C. The viral DNA was then extracted with the aid of a phenol/chloroform mixture, and then precipitated with 10 two volumes of absolute ethanol at -20°C for 16 hours and then centrifuged at 10,000 g for 15 minutes at 4°C. The DNA pellets were dried, and then taken up in a minimum volume of sterile ultrapure water. 15 1.2 Isolation of viral genomic RNA ■ The genomic RNA of each virus was extracted using the "guanidinium thiocyanate/phenol-chloroform" technique described by P. Chomczynski and . N. Sacchi (Anal. Biochem. 1987. 162. 156-159). 20 1.3 Molecular biology techniques All the constructions of plasmids were carried out using the standard molecular biology techniques described by Sambrook et al. (Molecular Cloning: A 25 Laboratory Manual. 2nd Edition. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 1989). All the restriction fragments used for the present invention were isolated with the aid of the "Geneclean" kit (BI0101 Inc., La Jolla, CA) . For all the 3 0 constructs, the cloned DNA fragments, as well as the junctions with the expression vector, were sequenced by the Sanger method (Sambrook et al., 1989). 1.4 PCR and RT-PCR 35 The oligonucleotides specific to the genes or gene fragments cloned were synthesized, some of them containing, in some cases., at their 5' end, restriction sites facilitating the cloning of . the amplified fragments. The reverse transcription (RT) reactions and - 31 - the polymerase chain reaction (PCR) were carried out according to standard techniques (Sambrook et al., 1989) . 5 1.5 Large-scale purification of plasmids The production, on the scale of about ten mg, of purified plasmids entering into the vaccinal compositions was carried out by the caesium chloride-ethidium bromide gradient method (Sambrook et al., 10 1989) . Example 2: Basic plasmid constructs The eukaryotic expression plasmid pVR1020 (C.J. Luke et al. J. of Infectious Diseases, 1997, 175, 95-15 97) , derived from the plasmid pVR1012 (Figure No. 1, Figure 1 and Example 7 of W0-A-9803199) , contains the coding phase of the signal sequence of the human tissue plasminogen activator (tPA). A plasmid pVR102 0 is modified by BamHI-Bglll 2 0 digestion and insertion of a sequence containing several cloning sites (BamHI, NotI, EcoRI, Xbal, Pmll, PstI, Bglll) and resulting from the pairing of the following oligonucleotides: PB3 2 6 (4.0 mer) (SEQ ID NO 1) 2 5 5' GATCTGCAGCACGTGTCTAGAGGATATCGAATTCGCGGCC 3' and PB329 (40 mer) (SEQ ID NO 2) 5' GATCCGCGGCCGCGAATTCGATATCCTCTAGACACGTGCT 3'. The vector thus obtained, having a size of about 5105 base pairs (or bp), is called pABllO (Figure 3 0 No . 2 ) . Intron II of the rabbit (3-globin gene is cloned into the vector pCRII (Invitrogen, Carlsbad, CA, USA) after production of the corresponding DNA fragment by PCR with the aid of the following oligonucleotides: 35 SB090 (20 mer) (SEQ ID NO 3) 51 TTGGGGACCCTTGATTGTTC 31 and SB091 (21 mer) (SEQ ID NO 4) 5' CTGTAGGAAAAAGAAGAAGGC 3' - 32 - using as template the genomic DNA of rabbit peripheral blood cells. The resulting plasmid is designated pNS050. The expression plasmid pABllO is modified by 5 introducing the sequence of intron II of the rabbit globin gene into the Sail site situated upstream of the ATG of the signal peptide of tissue plasminogen activator (tPA) . The sequence of intron II of the rabbit globin gene is amplified by polymerase chain 10 reaction (PCR) from the plasmid pNS050 using the following oligonucleotide pair: LF001 (30 mer) (SEQ ID NO 5) 5' CTCCATGTCGACTTGGGGACCCTTGATTGT 31 and LF002 (30 mer) (SEQ ID NO 6) 15 51 CTCCATGTCGACCTGTAGGAAAAAGAAGAA 3' The PCR product (573 base pairs or bp) is digested with Sail and cloned into the plasmid pABllO previously linearized with Sail, to generate the plasmid pLF999 of about 5678 bp. 20 Example 3: Plasmids encoding the various forms of the bovine herpesvirus type 1 (BHV-1) antigens Fragments of viral DNA containing the gB, gC and gD genes of the B901 strain of BHV-1 are isolated 25 by digesting the viral genome with various restriction enzymes, by separating them by agarose gel electrophoresis and by analysing them by Southern blotting with the aid of probes corresponding to fragments of the gB, gC and gD genes of the ST strain 30 of BHV-1 (Leung-Tack P. et al. , Virology, 1994, 199, 409-421). The BHV-1 Colorado strain [Cooper] (ATCC number VR-864) can also be used. The fragments thus identified are cloned into the vector pBluescript SK+ (Stratagene, La Jolla, CA, USA) and are at the origin 3 5 of the clonings of the three genes into the expression vector pVRl012. 3.1 Plasmids encoding the various forms of BHV-1 gB - 33 - 3.1.1 pPB2 80: gB gene (native form) cloned into the vector pVR1012 Two Xhol-Xhol fragments containing the 5' and 3 ' portions of the BHV-1 gB gene are identified by Southern blotting and cloned into the vector pBluescript SK+ (Stratagene, La Jolla, CA, USA) previously digested with Xhol. The plasmids thus obtained are designated pPB12 8 and pPBH7 respectively. The plasmid pPB128, containing the 5' fragment of the gB gene, is digested with NotI and Xhol, generating a fragment of 1708 bp (fragment A). The plasmid pPB117, containing the 3' portion of the gB gene, is digested with Xhol and StuI, generating a fragment of 1345 bp. The latter fragment is cloned into the vector pBluescript KS+ (Stratagene, La Jolla, CA, USA) previously digested with EcoRV and Xhol. The resulting plasmid is called pPB279. The plasmid pPB279 is then digested with Xhol and BamHI, generating a DNA fragment of 1413 bp (fragment B). Fragments A and B are then cloned into a vector pBluescript KS + digested with NotI and BamHI, generating plasmid pPB27 8 (about 60 63 bp) and allowing the reconstitution of the BHV-1 gB gene. The vector pPB27 8 then serves as template during a PCR reaction carried out with the following oligonucleotides: PB23 4 (30 mer) (SEQ ID NO 7) 5 1 TTGTCGACATGGCCGCTCGCGGCGGTGCTG 3 ' and PB235 (21 mer) (SEQ ID NO 8) 5' GCAGGGCAGCGGCTAGCGCGG 3 ' . The PCR product (146 bp) is then digested with the restriction enzymes Sail and Nhel. The plasmid pPB278 is digested with Nhel and BamHI, The fragment of 2728 bp thus obtained and the PCR fragment previously digested are ligated into the vector pVRl012 (Example 2) previously digested with Sail and BamHI, thus generating the plasmid pPB2 80, having a size of about 7742 bp. ■ _ 34 - The BHV-1 gB gene encodes a protein of 933 amino acids. 3.1.2 pPB281: gB gene (A[TM-Cter] form) cloned into the 5 vector pVRl012 The truncated form (deleted for its transmembrane (TM) and carboxy-terminal (Cter) domains) of the BHV-1 gB gene is obtained by ligating into the plasmid pVR1012 (Example 2) predigested with Sail and 10 BamHI, both a fragment having a size of 223 4 bp obtained after digestion with Sall-PvuII of the plasmid pPB280 (Example 3.1.1) and a fragment .of 56 bp obtained by pairing of the following oligonucleotides: PB511 (52 mer) (SEQ ID NO 9) 15 5' CTGCACGAGCTCCGGTTCTACGACATTGACCGCGTGGTCAAGACGGACTGAG 3 ' and PB512 (57 mer) (SEQ ID NO 10) 5' GATCCTCAGTCCGTCTTGACCACGCGGTCAATGTCGTAGAACCGGAGCTCGT GCAG 3 ' 2 0 The plasmid thus generated has a size of about 7154 bp and is called pPB281. The truncated gB gene of BHV-1 encodes a protein of 759 amino acids. 3.1.3 pSB115: gB gene (tPA A[TM-Cter] form) cloned into 2 5 the vector pABllO The tPA A[TM-Cter] form of the BHV-1 gB gene is amplified by PCR from the template pPB2 81 (Example 3.1.2) and with the aid of the following primers: SB221 (39 mer) (SEQ ID NO 11) 3 0 5 ' AAAATTTCGATATCCGCCGCGGGGCGACCGGCGACAACG 3 1 and SB222 (33 mer) (SEQ ID NO 12) 5 ' GGAAGATCTTCAGTCCGTCTTGACCACGCGGTC 3 ' The amplification product (2088 bp) is digested with the enzymes EcoRV and Bglll and cloned into the 35 vector pABllO (Example 2) previously digested with EcoRV and Bglll, generating the plasmid pSBH5, having a size of about 7154 bp. - 3 5 - The tPA A[TM-Cter] form of the gB gene encodes a glycoprotein of 729 amino acids, containing the extracellular domain of the BHV-1 gB glycoprotein. 5 3.2. Plasmids encoding the various forms of BHV-1 gC 3.2.1 pPB264: gC gene (native form) cloned into the vector pVR1012 A BamHI-Hindlll fragment of 3.5 kb containing 10 the complete BHV-1 gC gene is identifed by Southern blotting and cloned into the vector pBluescript SK+. The plasmid thus obtained is called pP-B287. The plasmid pPB2 87 is then digested with Ncol-BssSI. A digestion fragment having a size of 1492 bp is 15 obtained. It is ligated with a synthetic DNA fragment obtained by the pairing of the following oligonucelotides PB507 (37 mer) (SEQ ID NO 13) 5 ' TCGTGCCTGCGGCGCAAGGCCCGGGCGCGCCTGTAGT 3' and 20 PB5 0 8 (37 mer) (SEQ ID NO 14) 5' CTAGACTACAGGCGCGCGCGGGCCTTGCGCCGCAGGC 3', into the plasmid pLitmus 28 (New England Biolabs, Inc., Beverly, MA, USA) predigested with Ncol and Xbal, generating the intermediate plasmid pPB290. 25 The fragment of 1554 bp derived from the digestion of pPB290 with PstI and Xbal is cloned into the vector pVRl012 (Example 2) previously digested with PstI and Xbal, thus generating the plasmid pPB2 64, having a size of about 6427 bp. The BHV-1 gC gene 3 0 encodes a protein of 508 amino acids. 3.2.2 pPB292: gC gene (A[TM-Cter] form) cloned into the vector pVRl012 The truncated form of the BHV-1 gC gene is 3 5 obtained by ligating the following three DNA fragments into the vector pVR1012 (Example 2) previously digested with PstI and Xbal: (a) a fragment of 103 5 bp derived from the digestion of pPB2 64 (Example 3.2.1) with PstI and Xhol, - 36 - (b) a fragment of 3 50 bp derived from the digestion of pPB2 64 with Xhol and BanI and (c) a synthetic fragment of 43 bp resulting from the pairing of the oligonucleotides PB513 and 5 PB514. These oligonucleotides are the following: PB513 (43 mer) (SEQ ID NO 15) 5' GCACCGCTGCCCGAGTTCTCCGCGACCGCCACGTACGACTAGT 3' and PB514 (43 mer) (SEQ ID NO 16) 10 5' CTAGACTAGTCGTACGTGGCGGTCGCGGAGAACTCGGGCAGCG 3'. The plasmid having a size of about 6305 bp thus obtained is called pPB292. The truncated gC gene of BHV-1 encodes a protein of 466 amino acids. 15 3.2.3 pSB116: gC gene (tPA A[TM-Cter] form) cloned into the vector pABllO The tPA A[TM-Cter] form of the BHV-1 gC gene is amplified by PCR from the template pPB292 (Example 3.2.2) and with the aid of the following primers: 20 SB22 3 (39 mer). (SEQ ID NO 17) 5' AAAATTTCGATATCCCGGCGGGGGCTCGCCGAGGAGGCG 3' and SB22 4 (32 mer) (SEQ ID NO 18) 5' GGAAGATCTCTAGTCGTACGTGGCGGTCGCGG 3' The amplification product (13 62 bp) is digested 25 with the enzymes EcoRV and Bglll and cloned into the vector pABllO (Example 2) previously digested with EcoRV and Bglll, generating the plasmid pSBH6, having a size of about 6404 bp. The tPA A[TM-Cter] form of the gC gene encodes 3 0 a glycoprotein of 47 9 amino acids, containing the extracellular domain of the BHV-1 gC glycoprotein. 3.3 Plasmids encoding the various forms of BHV-1 gD 35 3.3.1 pPB148: gD gene (native form) cloned into the vector pVR1012 A Xhol-Xhol fragment of 5 kb containing the BHV-1 gD gene is identified by Southern blotting and - 37 - cloned into the vector pBluescript SK+ predigested with Xhol, generating the plasmid pPB147. A fragment of 325 bp derived from the digestion of pPBl47 with Ndel and BsrBI and a fragment of 943 bp 5 derived from the digestion of pPB147 with Ndel and Styl are then ligated into the vector pVR1012 (Example 2) predigested with EcoRV and Xbal, thus generating the plasmid pPB148, having a size of about 6171 bp. The BHV-1 gD gene encodes a protein of 417 amino acids. 10 3.3.2 pPB284: gD gene (A[TM-Cter] form) cloned into the vector PVR1012 The truncated gD gene of BHV-1 is obtained from a fragment obtained after PCR amplification carried out 15 on the genomic DNA of the B901 strain of the BHV-1 virus previously digested with PstI and Xbal and with the aid of the following primer pair: PB497 (33 mer) (SEQ ID NO 19) 51 TTTCTGCAGATGCAAGGGCCGACATTGGCCGTG 3' and 2 0 PB498 (31 mer) (SEQ ID NO 20) 5' TTTCTAGATTAGGGCGTAGCGGGGGCGGGCG 3'. This PCR fragment is then cloned into the plasmid pVR1012 (Example 2) previously digested with PstI and Xbal, generating the plasmid pPB2 84, having a 25 size of about 5943 bp. The. truncated gD gene of BHV-1 encodes a protein of 3 55 amino acids. 3.3.3 pSBH7: gD gene (tPA A[TM-Cter] form) cloned into the vector pABllO 3 0 The tPA A[TM-Cter] form of the BHV-1 gD gene is amplified by PCR from the pPB2 84 template (Example 3.3.2) and with the aid of the following primers: SB225 (39 mer) (SEQ ID NO 21) 5' AAAATTTCGATATCCCCCGCGCCGCGGGTGACGGTATAC 3' and 35 SB226 (33 mer) (SEQ ID NO 22) 5' GGAAGATCTTTAGGGCGTAGCGGGGGCGGGCGG 3'. The amplification product (1029 bp) is digested with the enzymes EcoRV and Bglll and cloned into the vector pABllO (Example 2) previously digested with - 38 - EcoRV and Bglll, generating the plasmid pSBH7, having a size of about 6071 bp. The tPA A[TM-Cter] form of the gD gene encodes a glycoprotein of 3 68 amino acids, containing the 5 extracellular domain of the BHV-1 gD glycoprotein. Example 4: Plasmids encoding the various forms of the bovine respiratory sencitial virus (BRSV) antigens The genes encoding the F and G antigens of the 10 BRSV virus are obtained by RT-PCR from the viral RNA of the Snook strain (Thomas et al. Research in Vet. Science, 1982, 33, 170-182). The BRSV A 51908 strain (ATCC number VR-794) may also be used. 15 4.1 Plasmids encoding the various forms of BRSV-F 4.1.1 pSBl07: F gene (native form) cloned into the vector pVRl012 The F gene of the Snook strain of BRSV is 2 0 amplified by RT-PCR using the viral RNA as template and with the aid of the following primers: SB210 (34 mer) (SEQ ID NO 23) 5 ' AAATTTTCTGCAGATGGCGACAACAGCCATGAGG 3 ' and SB211 (35 mer) (SEQ ID NO 24) 25 5' TTAAGGATCCTCATTTACTAAAGGAAAGATTGTTG 3'. The amplification product, having a size of 173 9 bp, is digested with the enzymes PstI and BamHI and cloned into the vector pVR1012 (Example 2) previously digested with PstI and BamHI, thus 3 0 generating the plasmid pSB107, having a size of about 65 83 bp. The F gene of the BRSV virus encodes a protein of 574 amino acids. 3 5 4.1.2 pSB108: F gene (A[TM-Cter] form) cloned into the vector pVRl012 The truncated form of the F gene of the Snook strain of BRSV is amplified by RT-PCR using the viral - 39 - RNA as template and with the aid of the following primers: SB210 (SEQ ID NO 23) and SB212 (39 mer) (SEQ ID NO 25) 5' AATTTTGGATCCTCATGTGGTGGATTTTCCTACATCTAC 31. The amplification product (1581 bp) is digested with the enzymes PstI and BamHI and cloned into the vector pVRl012 (Example 2) previously digested with PstI and BamHI, generating the plasmid pSBl08, having a size of about. 643 0 bp. The truncated form of the F gene encodes a glycoprotein of 523 amino acids,-- containing the extracellular domain of the BRSV F glycoprotein. 4.1.3 pSBll4: F gene (tPA A[TM-Cter] form) cloned into the vector pABllO The tPA A[TM-Cter] form of the F gene of the BRSV Snook strain is amplified by RT-PCR using the viral RNA as template and with the aid of the following primers: SB212 (SEQ ID NO 25) and SB22 0 (3 8 mer) (SEQ ID NO 26) 5' AAAATTCACGTGAACATAACAGAAGAATTTTATCAATC 3'. The amplification product (1516 bp) is digested with the enzymes Pmll and Bglll and cloned into the vector pABllO (Example 2) previously digested with Pmll and Bglll, generating the plasmid pSB114, having a size of about 6572 bp. The tPA A[TM-Cter] form of the F gene encodes a glycoprotein of 53 5 amino acids, containing the extracellular domain of the BRSV F glycoprotein. 4.2 Plasmids encoding the various forms of BRSV-G In the case of the BRSV G protein (type II glycoprotein), the signal sequence and the transmembrane sequence are indistinguishable, requiring the addition of a signal sequence upstream of the sequence corresponding to the extracellular domain during the deletion of the transmembrane domain. - 40 - The plasmid pABllO (Example 2) is used for the construction of the plasmids containing the truncated forms of the gene encoding the BRSV G protein. 5 4.2.1 pSBl09: G gene (native form) cloned into the vector pVR1012 The G gene of the BRSV Snook strain is amplified by RT-PCR using the viral RNA as template and with the aid of the following primers: 10 SB213 (32 mer) (SEQ ID NO 27) 5' ACGCGTCGACATGTCCAACCATACCCATCATC 3' and SB214 (38 mer) (SEQ ID NO 28) 5' TTAAAATCTAGATTAGATCTGTGTAGTTGATTGATTTG 3'. The amplification product (784 bp) is digested 15 with enzymes Sail arid Xbal and cloned into the vector pVR1012 (Example 2) previously digested with Sail and Xbal, generating, the plasmid pSB109, having a size of about 5661 bp. . The BRSV G gene encodes a glycoprotein of 257 20 amino acids. 4.2.2 pSBllO: G gene (tPA A[TM-Cter] form) cloned into the vector pABllO The truncated form of the G gene of the BRSV 25 Snook strain is amplified by RT-PCR using the viral RNA as template and with the aid of the following primers: SB215 (33 mer) (SEQ ID NO 29) 51 TTTTAAGGATCCGCTAAAGCCAAGCCCACATCC 31 and SB216 (33 mer) (SEQ ID NO 30) 3 0 5' TTAAAATCTAGATTAGATCTGTGTAGTTGATTG 3'. The amplification product (666 bp) is digested with the enzymes BamHI and Xbal and cloned into the vector pABllO (Example 2) previously digested with BamHI' and Xbal, generating the plasmid pSBllO, having a 35 size of about 5660 bp. The tPA A[TM-Cter] form of the BRSV virus G gene encodes a glycoprotein of 218 amino acids, containing the extracellular domain of the G - 41 - glycoprotein, but preceded by the signal sequence of the tissue plasminogen activator. Example 5: Plasmids encoding the various forms of the 5 bovine viral diarrhea virus type 1 (BVD-1) antigens The genes encoding the EO (glycoprotein of 48 kDa or gp48) and E2 (gp53) antigens of the type 1 BVDV viruses are obtained by RT-PCR from the viral RNA of the Osloss strain (L. De Moerlooze et al. J. Gen. 10 Virol. 1993, 74, 1433-1438; A. Renard et al. , DNA, 1985, 4, 439-438; A. Renard et al. Ann. Rech. Vet., 1987, 18, 121-125). The NADL (ATCC VR-534) or New York (ATCC VR-524) strains may also be used. 15 5.1 Plasmids encoding the various forms of EO of the BVDV type 1 Osloss strain 5.1.1 pLFl028: EO gene (native form) cloned into the vector pVRl012 20 The complementary DNA (cDNA) of the EO gene of the Osloss strain is synthesized from the corresponding viral RNA with the aid of the primer LF051 and amplified by the PCR reaction with the aid of the following oligonucleotide pair: 25 LF050 (36 mer) (SEQ ID NO 31) 51 CATACCGTCGACATGAAGAAACTAGAGAAAGCCCTG 3' and LF051 (40 mer) (SEQ ID NO 32) 5 ' CATACCGGATCC'TCAGGCTGCATATGCCCCAAACCATGTC 3 ' . The DNA fragment of about 765 bp obtained by 30 digesting, the PCR product with Sail and BamHI is ligated with a fragment of 4866 bp resulting from the digestion of pVRl012 (Example 2) with Sail and BamHI in order to generate the plasmid pLF1028 (about 563 6 bp). The EO gene of BVDV-1 strain Osloss encodes a protein 35 of 252 amino acids. An ATG codon is introduced into the sequence of the oligonucleotide LF050 so as to allow the initiation of the translation of the corresponding recombinant EO polypeptide. - 42 - 5.1.2 pLF1029: EO gene, ((3-globin tPA-EO) form cloned into the vector pLF999. The EO gene is synthesized by a PCR reaction 5 from the pLFl028 template (Example 5.1.1) and with the aid of the following oligonucleotide pair: LF052 (39 mer) (SEQ ID NO 33) 5 ' CATGACGCGGCCGCTATGAAGAAACTAGAGAAAGCCCTG 3 ' and LF053 (40 mer) (SEQ ID NO 34) 10 5 ' CATGACAGATCTTTAGGCTGCATATGCCCCAAACCATGTC 3 ' . The DNA fragment of about 77 0 bp obtained by digesting the PCR product with NotI and Bglll is ligated with a fragment of 5642 bp resulting from the digestion of pLF999 (Example 2) with NotI and Bglll in 15 order to generate the plasmid pLFl029 (about 6417 bp). The EO gene of BVDV-1 strain Osloss thus modified ((3-globin tPA-EO) encodes a protein of 283 amino acids. 2Q 5.2 Plasmids encoding the various forms of E2 of the BVDV type 1 Osloss strain 5.2.1 pLFl020: E2 gene (native form) cloned into the vector pVR1012 25 The cDNA of the E2 gene of the Osloss strain is synthesized from the corresponding viral RNA with the aid of the primer LF040 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF039 (33 mer) (SEQ ID NO 35) 3 0 5 ' CATGACGTCGACATGACGACTACTGCATTCCTG 3 1 and LF040 (36 mer) (SEQ ID NO 36) 5 1 CATGACAGATCTTCAACGTCCCGAGGTCATTTGTTC 3 ' . The DNA fragment of 123 5 bp obtained by digesting the PCR product with Sail and Bglll is 35 ligated with a fragment of 4860 bp resulting from the digestion of pVR1012 (Example 2) with Sail and Bglll in order to generate the plasmid pLF1020 (about 6100 pb) . The E2 gene of BVDV-1 strain Osloss encodes a protein of 409 amino acids. - 43 - An ATG codon is introduced into the sequence of the oligonucleotide LF039 so as to allow the initiation of the translation of the corresponding recombinant E2 polypeptide. 5 5.2.2 pLF1021: E2 gene, ((3-globin tPA-E2 A[TM+Cter]) form cloned into the vector pLF999. The E2 gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR 10 reaction from the pLFl020 template (Example 5.2.1) and with the aid of the following oligonucleotide pair: LF041 (36 mer) (SEQ ID NO 37) 5' CATGACGCGGCCGCTATGACGACTACTGCATTCCTG 3' and LF042 (35 mer) (SEQ ID NO 38) 15 5' CATGACAGATCTCAAGCGAAGTAATCCCGGTGGTG 3. The DNA fragment of 1132 bp obtained by digesting the PCR product with NotI and Bglll is ligated with a fragment of 5642 bp resulting from the digestion of pLF999 (Example 2) with NotI and Bglll in 20 order to generate the plasmid pLF1021 (about 6779 bp) . The E2 gene of BVDV-1 strain Osloss thus modified ([3-globin tPA-E2 A[TM+Cter]) encodes a protein of 4 04 amino acids. 25 Example 6: Plasmids encoding the various forms of the bovine viral diarrhea virus type 2 (BVDV-2) antigens The genes encoding the E2 antigen (gp53) of the BVDV type 2 viruses are obtained by RT-PCR from the viral RNA of the strain 890 (J.F. Ridpath and S.R. 30 Bolin, Virology, 1995, 212, 36-46). The strain Q140 can also be used and may be obtained from the Quebec Ministry of Agriculture, Fisheries and Food, Armand-Frappier Institute (P. Tijssen et al. , Virology, 1996, 217, 356-361) . The strains 1373 and 296 may also be 35 used (J.F. Ridpath, BVDV Research Project, National Animal Disease Center, 2300 Dayton Avenue, Ames, USA). 6.1 Plasmids encoding the various forms of E2 of the type 2 - 890 strain - 44 - 6.1.1. pLFl022: E2 gene (native form) cloned into the vector pVR1012 The cDNA of the E2 gene of the strain 890 is 5 synthesized from the corresponding viral RNA with the aid of the primer LF044 amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF043 (36 mer) (SEQ ID NO 39) 51 ACTGTATCTAGAATGACCACCACAGCTTTCCTAATC 3' and 10 LF044 (39 mer) (SEQ ID NO 40) 5' ACTGTAAGATCTTTAAGTATTCACTCCAGCACCCATAGC 3'. The DNA fragment of about 1240 bp obtained by digesting the PCR product with Xbal and Bglll is ligated with a fragment of 4891 bp resulting from the 15 digestion of pVRl012 ' (Example 2) with Xbal and Bglll in order to generate the plasmid pLF1022 (about 613 6 bp) . The E2 gene of BVDV-2 strain 890 encodes a protein of 410 amino acids. An ATG codon is introduced into the sequence of 20 the oligonucleotide LF043 so as to allow the initiation of the translation of the corresponding recombinant E2 polypeptide. 6.1.2 pLF1023: E2 gene, (|3-globin tPA-E2 A[TM+Cter] ) 25 form, cloned into the vector pLF999 The E2 gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR reaction from the pLFl022 template (Example 6.2.1) and with the aid of the following oligonucleotide pair: 30 LF045 (41 mer) (SEQ ID NO 41) 5' CATGACGCGGCCGCCCTATGACCACCACAGCTTTCCTAATC 3' and LF046 (36 mer) (SEQ ID NO 42) 5' CATGACAGATCTTTATATGAACTCTGAGAAGTAGTC 3'. The DNA fragment of about 1140 bp obtained by 35 digesting the PCR product with NotI and Bglll is ligated with a fragment of 5642 bp resulting from the digestion of pLF999 (Example 2) with NotI and Bglll in order to generate the plasmid pLF1023 (about 6787 bp). - 45 - The E2 gene of BVDV-2 strain 890 thus modified ([3-globin tPA-E2 A[TM+Cter]) encodes a protein of 405 amino acids. 5 6.2 Plasmids encoding the various forms of EO of the type 2 - 890 strain 6.2.1 pLF 103 0: E0 gene (native form) cloned into the vector pVRl012 10 The cDNA of the E0 gene of the 890 strain is synthesized from the corresponding viral RNA with the aid of the LF065 primer and amplified- -by a PCR reaction with the aid of the following oligonucleotide pair: LF0 64 (39 mer) (SEQ ID NO 43) 15 5 ' CATACCGTCGACATGAGAAAGAAATTGGAGAAGGCACTG 3 ' and LF065 (39 mer) (SEQ ID NO 44) 5 ' CATACCG'GATCCTCATGCTGCATGAGCACCAAACCATGC 3 ' . The DNA fragment of about 7 68 bp obtained , by digesting the PCR product with Sail and BamHI is 20 ligated with a fragment of 4866 bp resulting from the digestion of pVRl012 (Example 2) with Sail and BamHI in order to generate the plasmid pLFl030 (about 5639 bp) . The E0 gene of BVDV-2 strain 890 encodes a protein of 2 53 amino acids. 25 An ATG codon is introduced into the sequence of the oligonucleotide LF064 so as to allow the initiation of the translation of the corresponding recombinant E0 polypeptide. 3 0 6.2.2 pLFl031: E0 gene, ([3-globin tPA-EO) form, cloned into the vector pLF999. The E0 gene is synthesized by a PCR reaction from the pLFl030 template (Example 6.2 .1. ) and with the aid of the following oligonucleotide pair: 35 LF066 (42 mer) (SEQ ID NO 45) 5 ' CATGACGCGGCCGCTATGAGAAAGAAATTGGAGAAGGCACTG 3 ' and LF067 (39 mer) (SEQ ID NO 46) 5' CATACCAGATCTTCATGCTGCATGAGCACCAAACCATGC 3'. ' . - 46 - The DNA fragment of about 770 bp obtained by digesting the PCR product with NotI and Bglll is ligated with a fragment of 5642 bp resulting from the digestion of pLF999 (Example 2) with NotI and Bglll in 5 order to generate the plasmid pLF1031 (about 6417 bp). The EO gene of BVDV-2 strain 890 thus modified ([3-globin tPA-EO) encodes a protein of 283 amino acids. Example 7: Plasmids encoding the various forms of the 10 bovine parainfluenza virus type 3 (bPI-3) antigens The genes encoding the hemagglutinin-neuraminidase (HN) and fusion (F) antigens of the bPI-3 virus are obtained by RT-PCR from the viral RNA of the Reisinger SF-4 strain (accessible from ATCC under the 15 number VR-281). 7.1 Plasmids encoding the various forms of HN of the bPI-3 SF-4 strain 2 0 7.1.1 pLF1024: HN gene (native form) cloned into the vector pVRl012 The cDNA of the HN gene of the SF-4 strain is synthesized from the corresponding viral RNA with the aid of the primer LF048 and amplified by a PCR reaction 25 with the aid of the following oligonucleotide pair: LF047 (39 mer) (SEQ ID NO 47) 5' CATATCGTCGACATGGAATATTGGAAACACACAAACAGC 3' and LF048 (38 mer) (SEQ ID NO 48) 5' CATGACGATATCTAGCTGCAGTTTTTCGGAACTTCTGT 3'. 3 0 The DNA fragment of 172 6 bp obtained by digesting the PCR product with Sail and EcoRV is ligated with a fragment of 4896 bp resulting from the digestion of pVRl012 (Example 2) with Sail and EcoRV in order to generate the plasmid pLF1024 (about 6619 bp). 3 5 The bPI-3 HN gene encodes a protein of 572 amino acids. 7.1.2 pLF1025: HN gene, ([3-globin tPA-E2 A[TM]) form, cloned into the vector pLF999 - 47 - The HN gene deleted for its transmembrane domain is synthesized by a PCR reaction from the PLF1024 template (Example 7.1.1) with the aid of the following oligonucleotide pair: 5 LF0 5 8 (33 mer) (SEQ ID NO 49) 5' CATACTGCGGCCGCTTTAATTCAAGAGAACAAT 3' and LF0 59 (35 mer) (SEQ ID NO 50) 51 CATATCGATATCTAGCTGCAGTTTTTCGGAACTTC 3'. The DNA fragment of 1566 bp obtained by 10 digesting the PCR product with NotI and. EcoRV is ligated with a fragment of 5663 bp resulting from the digestion of pLF999 (Example 2) with .NotI and EcoRV in order to generate the plasmid pLFl025 (about 7229 bp) . The bPI-3 HN gene thus modified ([3-globin tPA-15 E2 A[TM]) encodes a protein of 548 amino acids. 7.2 Plasmids encoding the various forms of F of the bPI-3 SF-4 strain 2 0 7.2.1 pLF102 6: F gene (native form) cloned into the vector pVR10l2 The cDNA of the F gene of strain SF-4 is synthesized from the corresponding viral RNA with the aid of the primer LF061 and amplified by a PCR reaction 25 with the.aid of the following oligonucleotide pair: LF060 (36 mer) (SEQ ID NO 51) 51 CATATCGTCGACATGATCATCACAAACACAATCATA 3' and LF061 (36 mer) (SEQ ID NO 52) 5' CATGACCAGATCTTATTGTCTATTTGTCAGTATATA 3'. 3 0 The DNA fragment of 1628 bp obtained by digesting the PCR product with Sail and Bglll is ligated with a fragment of 4860 bp resulting from the digestion of pVRl012 (Example 2) with Sail and Bglll in order.to generate the plasmid pLF1026 (about 6488 bp). 35 The bPI-3 F gene encodes a protein of 550 amino acids. 7.2.2 pLF1027: F gene, ([3-globin tPA-F A[TM+Cter]) form, cloned into the vector pLF999 - 48 - The F gene deleted for its transmembrane and C-terminal domains is synthesized by a PCR reaction from the pLR102 6 template (Example 7.2.1) and with the aid of the following oligonucleotide pair: 5 LF062 (42 mer) (SEQ ID NO 53) 5 ' CATACTGCGGCCGCTCAAATAGACATAACAAAACTGCAACGT 3 1 and LF063 (41 mer) (SEQ ID NO 54) 51 CATATCGATATCTATGCACTAGATTGATACCAACTTCCAAC 3'. The DNA fragment of 1434 bp obtained by 10 digesting the PCR product with NotI and EcoRV is ligated with a fragment of 5663 bp resulting from the digestion of pLF999 (Example 2) with-NotI and EcoRV in order to generate the plasmid pLFl027 (about 7097 bp). The bPI-3 F gene thus modified (P~globin tPA-F 15 A[TM+Cter]) encodes a protein of 504 amino acids. Example 8: Plasmids encoding the various forms of the pseudorabies virus (PRV) antigens The genes encoding the PRV glycoproteins gB, gC 2 0 and gD are obtained by PCR from the viral DNA of the NIA3 strain (M. Riviere et al. J. Virol. 66, 3424-3434; A. Baskerville et al. The Veterinary Bulletin, 1973, 43 No. 9). Mutants of the PRV NIA3 strain may also be used and are described in US-A-4,680, 176 and deposited with 25 the Collection Nationale de Cultures de Microorganismes (CNCM), Institut Pasteur, Paris, France, under the references 1-351 and 1-352. 30 8.1. Plasmids encoding the various forms of PRV-gB 8.1.1. pSBlOl: gB gene (native form) cloned into the vector pVRl012 The gB gene of the PRV NIA3 strain is amplified by PCR using the viral DNA as template and with the aid 35 of the following primers: SB201 (36 mer) (SEQ ID NO 55) 5' TTTTAAGATATCATGCCCGCTGGTGGCGGTCTTTGG 3' and SB202 (39 mer) (SEQ ID NO 56) 5' TTTTAAGGATCCCTACAGGGCGTCGGGGTCCTCGCTCTC 3'. - 49 - The amplification product (2766 bp) is digested with the enzymes EcoRV and BamHI and cloned into the vector pVRl012 (Example 2) previously digested with EcoRV and BamHI, generating the plasmid pSBlOl, having 5 a size of about 7 631 bp. The PRV gB gene encodes a glycoprotein of 913 amino acids. 8.1.2 pSB102: gB gene (A[TM-Cter] form) cloned into the 10 vector pVR.1012 The truncated form of the gB gene of the PRV NIA3 strain is amplified by PCR using-the viral DNA as template and with the aid of the following primers: SB2 01 (SEQ ID NO 55) and 15 SB2 03 (39 mer) (SEQ ID NO 57) 5 ' TTTTAAGGATCCCTAGTGGTCCACCTTGACCACGCGGTC 3 ' . The amplification product (2262 bp) is digested with the enzymes EcoRV and BamHI and cloned into the vector .pVRl012 (Example 2) previously digested with 20 EcoRV and BamHI, generating the plasmid pSB102, having a size of about 7142 bp. The truncated form (A[TM-Cter]) of the gB gene encodes a glycoprotein of 750 amino acids, containing the extracellular domain of the PRV gB glycoprotein. 25 8.1.3 pNS009: gB gene (tPA A[TM-Cter] form) cloned into the vector pABllO The tPA A[TM-Cter] form of the gB gene of the PRV NIA3 strain is amplified by PCR from the template 3 0 pSBlOl (Example 8.1.1) and with the aid of the following primers: SB2 03 (SEQ ID NO 57) and SB217 (39 mer) (SEQ ID NO 58) 51 AAAATTTCGATATCCACCTCGGCCTCGCCGACGCCCGGG 3'. 35 The amplification product (2088 bp) is digested with the enzymes EcoRV and Bglll and cloned into the vector pABllO (Example 2) previously digested with EcoRV and Bglll, generating the plasmid pNS009, having a size of about 7127 bp. - 50 - . r The tPA A[TM-Cter] form of the gB gene encodes a glycoprotein of 720. amino acids, containing the extracellular domain of the PRV gB glycoprotein. 5 8.2 Plasmids encoding the various forms of PRV-gC 8.2.1 pSBl03: gC gene (native form) cloned into the vector pVRl012 The gC gene of the PRV NIA3 strain is amplified 10 by PCR using the viral DNA as template and with the aid of the following primers: SB204 (36 mer) (SEQ ID NO 59) 5' TTTTAAGATATCATGGCCTCGCTCGCGCGTGCGATG 31 and SB2 05 (37 mer) (SEQ ID NO 60) 15 5 ' TTTTAAAGATCTTTAAGGCCCCGCCTGGCGGTAGTAG 3' . The amplification product (1452 bp) is digested with the enzymes. EcoRV and Bglll and cloned into the vector pVP.1012 (Example 2) previously digested with EcoRV and Bglll, generating the plasmid pSB103, having 20 a size of about 6323 bp. The PRV gC gene encodes a glycoprotein of 479 amino acids. 8.2.2 pSB104: gC gene (A[TM-Cter] form) cloned into the 25 vector pVR1012 The truncated form of the gC gene of the PRV NIA3 strain is amplified by PCR using the viral DNA as template and with the aid of the following primers: SB2 04 (SEQ ID NO 59) and 30 SB206 (36 mer) (SEQ ID NO 61) 5' TTTTAAAGATCTTTAGGGGGAGGCGTCGTAGCGCTG 3'. The amplification product (1332 bp) is digested with the enzymes EcoRV and Bglll and cloned into the vector pVRl012 (Example 2) previously digested with 35 EcoRV and Bglll, generating the plasmid pSB104, having a size of about 6206 bp. The truncated form (A[TM-Cter]) of the gC gene encodes a glycoprotein of 440 amino acids, containing the extracellular domain of the PRV gC glycoprotein. - 51 - 8.2.3 pNS012: gC gene (tPA A[TM-Cter] form) cloned into the vector pABllO The tPA A[TM-Cter] form of the gC gene of the 5 PRV NIA3 strain is amplified by PCR from the template pSB103 (Example 8.2.1) and with the aid of the following primers: SB2 0 6 (SEQ ID NO 61) and SB218 (39 mer) (SEQ ID NO 62) 10 5' AAAATTTCGATATCCACGGCGCTCGGCACGACGCCCAAC 3'. The amplification product (1270 bp) is digested with the enzymes EcoRV and Bglll and- cloned into the vector pABllO (Example 2) previously digested with EcoRV and Bglll, generating the plasmid pNS012, having 15 a size of about 6311 bp. The tPA A[TM-Cter] form of the gC gene encodes a glycoprotein of 448 amino acids, containing the extracellular domain of the PRV gC glycoprotein. 20 8.3 Plasmids encoding the various forms of PRV-gD 8.3.1 pSBl05: gD gene (native form) cloned into the vector pVRl012 The gD gene of the PRV NIA3 strain is amplified 2 5 by PCR using the viral DNA as template and with the aid of the following primers: SB2 07 (3 6 mer) (SEQ ID NO 63) 51 AATTTTGATATCATGCTGCTCGCAGCGCTATTGGCG 3' and SB208 (36 mer) (SEQ ID NO 64) 3 0 5' AATTTTGGATCCCTACGGACCGGGCTGCGCTTTTAG 3'. The amplification product (1227 bp) is. digested with the enzymes EcoRV and BamHI and cloned into the vector pVR1012 (Example 2) previously digested with EcoRV' and BamHI, generating the plasmid pSB105, having 35 a size of about 6104 bp. The PRV gD gene encodes a glycoprotein of 4 04 amino acids. - 52 - 8.3.2 pSBl06: gD gene (A[TM-Cter] form) cloned into the vector pVP.1012 The truncated form of the gD gene of the PRV NIA3 strain is amplified by PCR using the viral DNA as 5 template and with the aid of the following primers: SB207 (SEQ ID NO 63) and SB209 (40 mer) (SEQ ID NO 65) 51 AAATTTTGGATCCCTAGCGGTGGCGCGAGACGCCCGGCGC 3'. The amplification product (1077 bp) is digested 10 with the enzymes EcoRV and BamHI and cloned into the vector pVRl012 (Example 2) previously digested with EcoRV and BamHI, generating the plasmid pSBl06 having a size of about 5957 bp. The truncated form (A[TM-Cter]) of the gD gene 15 encodes a glycoprotein of 355. amino acids, containing the extracellular domain of the PRV gD glycoprotein. 8.3.3 pPB238: gD gene (tPA A[TM-Cter] form) cloned into the vector pABllO 2 0 The tPA A[TM-Cter] form of the gD gene of the PRV NIA3 strain is amplified by PCR from the template pSB10 5 (Example 8.3.1) and with the aid of the following primers: SB209 (SEQ ID NO 65) and 25 SB219 (39 mer) (SEQ ID NO 66) 51 AAAATTTCGATATCCACCTTCCCCCCGCCCGCGTACCCG 3'. The amplification product (1015 bp) is digested with the enzymes EcoRV and BamHI and cloned into the vector pABllO (Example 2) previously digested with 3 0 EcoRV and Bglll, generating the plasmid pPB23 8, having a size of about 6056 bp. The tPA A[TM-Cter] form of the gD gene encodes the glycoprotein of 3 63 amino acids, containing the extracellular domain of the PRV gD glycoprotein. 35. Example 9: Plasmids encoding the various forms of the porcine reproductive respiratory syndrome virus (PRRSV), strain Lelystad, antigens - 53 - The genes encoding the PRRSV 0RF3, 0RF5 and 0RF6 proteins are obtained by RT-PCR from the viral RNA of the Lelystad strain (J. Meulenberg et al. Virology, 1993, 19, 62-72; WO-A-92-21375) , deposited June 5, 1991 5 with the Collection Nationale de Cultures de Microorganismes (CNCM), Institut Pasteur, Paris, ■ France, under the reference 1-1102. 9.1 Plasmids encoding the various forms of the PRRSV 10 Lelystad strain ORF3 9.1.1 pLF1009: ORF3 gene (native form) cloned into the vector pVRl012 The cDNA of the ORF3 gene of the Lelystad 15 strain is synthesized from the corresponding viral RNA with the aid of the primer LF02 8 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF02 7 (30 mer) (SEQ ID NO 67) 2 0 5 ' CACTACGATATCATGGCTCATCAGTGTGCA 3 1 and LF028 (30 mer) (SEQ ID NO 68) 5 ' CACTACAGATCTTTATCGTGATGTACTGGG 3 ' . The DNA fragment of 802 bp obtained by digesting the PCR product with EcoRV and Bgllll is 25 ligated with a fragment of 4879 bp resulting from the digestion of pVRl012 (Example 2) with EcoRV and Bgllll in order to generate the plasmid pLFl009 having a size of about 5681 bp. The PRRSV Lelystad 0RF3 gene encodes a protein 3 0 of 265 amino acids. 9.2 Plasmids encoding the various forms of the PRRSV Lelystad strain ORF5 35 9.2.1 pLFlOll: ORF5 gene (native form) cloned into the vector pVR1012 The cDNA of the 0RF5 gene of the Lelystad strain is synthesized from the corresponding viral RNA with the aid of the primer LF02 0 and amplified by a PCR - 54 - » reaction with the aid of the following oligonucleotide pair: LF019 (30 mer) (SEQ ID NO 69) 5' CTCACCGTCGACATGAGATGTTCTCACAAA 3' and 5 LF020 (30 mer) (SEQ ID NO 70) 5' CTCACCTCTAGACTAGGCCTCCCATTGCTC 31. The DNA fragment of 802 bp obtained by-digesting the PCR product with Sail and Xbal is ligated with a fragment of 4879 bp resulting from the digestion 10 of pvRl012 (Example 2) with Sail and Xbal in order to generate the plasmid pLFlOll having a size of about 5 6 81 bp. The PRRSV Lelystad ORF5 gene encodes a protein of 201 amino acids. 15 9.2.2 pLF1012: ORF5 gene (truncated form) cloned into the vector pABllO The ORF5 gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR 20 reaction from the template pLFlOll (Example 9.2.1) with the aid of the following oligonucleotide pair: LF021 (30 mer) (SEQ ID NO 71) 5' CACCTCGGATCCTTTGCCGATGGCAACGGC 31 and LF022 (33 mer) (SEQ ID NO 72) 2 5 5' CACCTCGGATCCTTAGACTTCGGCTTTGCCCAA 31. The DNA fragment of 432 bp obtained by digesting the PCR product with BamHI is ligated with a fragment of 5105 bp resulting from the digestion of pABllO (Example 2) with BamHI in order to generate the 3 0 plasmid pLF1012 having a size of about 553 7 bp. The PRRSV Lelystad ORF5 gene thus modified (tPA A[TM+Cter]) encodes a protein of 168 amino acids. 9.3 Plasmids encoding the various forms of the PRRSV 35 Lelystad strain ORF6 9.3.1 pLF1013: ORF6 gene (native form) cloned into the vector pVRl012 - 55 - The cDNA of the 0RF6 gene of the Lelystad . strain is synthesized from the corresponding viral RNA with the aid of the primer LF024 and amplified by a PCR reaction with the aid of the following oligonucleotide 5 pair: LF023 (30 mer) (SEQ ID NO 73) 5' CACTCAGTCGACATGGGAGGCCTAGACGAT 3' and LF02 4 (30 mer) (SEQ ID NO 74) 51 CACTCATCTAGATTACCGGCCATACTTGAC 3'. 10 The DNA fragment of 52 8 bp obtained by digesting the PCR product with Sail and Xbal is ligated with the fragment of 4881 bp resulting* in the digestion of pVRl012 (Example 2) with Sail and Xbal in order to generate the plasmid pLFl013 having a size of about 15 5409 bp. The PRRSV Lelystad ORF6 gene encodes a protein of 173 amino acids. 9.3.2 pLFlO14: ORF6 gene (truncated form) cloned into 20 the vector pABllO The ORF6 gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR reaction from the template pLFl013 (Example 9.3.1) with the aid of the following oligonucleotide pair: 25 LF025 (30 mer) (SEQ ID NO 75) 5' CACTACGGATCCGTGTCACGCGGCCGACTC 3' and LF026 (33 mer) (SEQ ID NO 76) 5 1 CACTACGGAT'CCTTAAACAGCTCGTTTGCCGCC 3 1 . The DNA fragment of 3 90 bp obtained by 3 0 digesting the PCR product with BamHI is ligated with a fragment of 5105 bp resulting from the digestion of pABllO (Example 2) with BamHI in order to generate the plasmid pLF1014 having a size of about 5495 bp. The PRRSV Lelystad ORF6 gene thus modified 35 (tPA A[TM+Cter]) encodes- a protein of 154 amino acids. Example 10: Plasmids encoding the various forms of the porcine reproductive respiratory syndrome virus (PRRSV), American strain ATCC VR-2332, antigens - 56 - The genes encoding the PRRSV virus 0RF3, 0RF5 and 0RF6 proteins are obtained by RT-PCR from the viral RNA of the American strain (M. Murtaugh et al. Arch Virol. 1995, 140, 1451-1460), deposited with the ATCC 5 under the number VR-2332. 10.1 Plasmids encoding the various forms of PRRSV VR-2332 strain ORF3 10 10.1.1 pLF1015: ORF3 gene (native form) cloned into the vector pVRl012 The cDNA of the ORF3 gene of the VR-2332 strain is synthesized from the corresponding viral RNA with the aid of the primer LF03 8 and amplified by a PCR 15 reaction with the aid of the following oligonucleotide pair : LF037 (30 mer) (SEQ ID NO 77) 51 CACTACGATATCATGGTTAATAGCTGTACA 3' and LF03 8 (30 mer) (SEQ ID NO 78) 2 0 51 CACTACTCTAGACTATCGCCGTACGGCACT 31. The DNA fragment of 769 bp obtained by digesting the PCR product with EcoRV and Xbal is ligated with a fragment of 4900 bp resulting from the digestion of pVR1012 (Example 2) with EcoRV and Bglll 25 in order to generate the plasmid pLFl015 having a size of about 5 6 69 bp. The PRRSV strain VR-2332 0RF3 gene encodes a protein of 254 amino acids. 3 0 10.2 Plasmids encoding the various forms of the PRRSV VR-2332 strain ORF5 10.2.1 pLFl017: ORF5 gene (native form) cloned into the vector pVRl012 35 The cDNA of the ORF5 gene of the VR-2332 strain is synthesized from the corresponding viral RNA with the aid of the primer LF030 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: - 57 - LF029 (30 mer) (SEQ ID NO 79) 5 ' CACTACGATATCATGTTGGAGAAATGCTTG 3 ' and LF030 (30 mer) (SEQ ID NO 80) 5 ' CACTACAGATCTCTAAGGACGACCCCATTG 3 ' . 5 The DNA fragment of 607 bp obtained by digesting the PCR product with EcoRV and Bglll is ligated with a fragment of 4879 bp resulting from the digestion of pVRl012 (Example 2) with EcoRV and Bglll in order to generate the plasmid pLF1017 having a size 10 of about 5486 bp. The PRRSV strain VR-2332 ORF5 gene encodes a protein of 200 amino acids. 10.2.2 pLFlO18: ORF5 gene (truncated form) cloned into 15 the vector pABllO The ORF5 gene deleted for its transmembrane and carboxy-terminal . domains is synthesized by a PCR reaction from the template pLFl017 (Example 10.2.1) with the aid of the following oligonucleotide pair: 20 LF031 (33 mer) (SEQ ID.NO 81) 5' CACTACGGATCCGCCAGCAACGACAGCAGCTCC 3' and LF032 (33 mer) (SEQ ID NO 82) 5 ' CACTACGGATCCTTAGACCTCAACTTTGCCCCT 3 ' . The DNA fragment of 42 6 bp obtained by 2 5 digesting the PCR product with BamHI is ligated with a fragment of 5105 bp resulting from the digestion of pABllO (Example 2) with BamHI in order to generate the plasmid pLFl018 having a size of about 5531 bp. The PRRSV strain VR-23 32 ORF5 gene thus 30 modified (tPA A[TM+Cter]) encodes a protein of 166 amino acids. 10.3 Plasmids encoding the various forms of the PRRSV VR-2332 strain ORF6 35 10.3.1 pLFl019: ORF6 gene (native form) cloned into the vector pVRl012 The cDNA of the ORF6 gene of the VR-2332 strain is synthesized from the corresponding viral RNA with - 58 - the aid of the primer LF034 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF033 (33 mer) (SEQ ID NO 83) 5 5' CACATCCTGCAGATGGGGTCGTCCTTAGATGAC 3' and LF034 (30 mer) (SEQ ID NO 84) 5' CACATCTCTAGATTATTTGGCATATTTGAC 31. The DNA fragment of 527 bp obtained by digesting the PCR product with PstI and Xbal is ligated 10 with a fragment of 4871 bp resulting from the digestion of pVRl012 (Example 2) with PstI and Xbal in order to generate the plasmid pLF1019 having - -a size of about 5398 bp. The PRRSV strain VR-2332 ORF6 gene encodes a 15 protein of 174 amino acids. 10.3.2 pLF1016: ORF6 gene (truncated form) cloned into the vector pABllO The ORF6 gene deleted for its transmembrane and 2 0 carboxy-terminal domains is synthesized by a PCR reaction from the template pLF1019 (Example 10.3.1) with the aid of the following oligonucleotide pair: LF03 5 (3 0 mer) (SEQ ID NO 85) 5' CACTACGGATCCGTGAGTCGCGGCCGACTG 3' and 25 LF036 (33 mer) (SEQ ID NO 86) 5' CACTACGGATCCTTAAACAGCTTTTCTGCCACC 3'. The DNA fragment of 3 90 bp obtained by digesting the PCR product with BamHI is ligated with a fragment of 5105 bp resulting from the digestion of 3 0 pABllO (Example 2) with BamHI in order to generate the plasmid pLF1016 having a size of about 5459 bp. The PRRSV strain VR-2332 ORF6 gene thus modified (tPA A[TM+Cter]) encodes a protein of 154 amino acids. 35 Example 11: Plasmids encoding the various forms of the swine influenza virus (SIV), strain H1N1, antigens The genes encoding the hemagglutinin (HA) and neuraminidase (NA) antigens of the swine influenza - 59 - virus type H1N1 are obtained by RT-PCR from the viral RNA of the "SW" H1N1 strain. Strains are available from the Virology Research Center, Armand-Frappier Institute, University of Quebec, Laval, Canada (D.S. 5 Arora et al., Virus Genes, 1997, 14, 251-254). See also G.W. Both et al., Proc. Natl. Acad. Sci. USA, 1983, 80, 6996-7000. 11.1 Plasmids encoding the various forms of SIV H1N1 strain HA 10 11.1.1 pLFlOOl: HA gene (native form) cloned into the vector pVRl012 The cDNA of the HA gene of the H1N1 strain is synthesized from the corresponding viral RNA with the 15 aid of the primer LF004 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF0 03 (30 mer) (SEQ ID NO 87) 5' CTCCATGATATCATGGAAGCAAAACTATTC 3' and LF004 (30 mer) (SEQ ID NO 88) 2 0 51 CTCCATCAGATCTTAAATGCATATTCTGCA 3'. The DNA fragment of 17 05 bp obtained by digesting the PCR product with EcoRV and Bglll is ligated with the fragment of 4879 bp resulting from the digestion of pVRl012 (Example 2) with EcoRV and Bglll 25 in order to generate the plasmid pLFlOOl having a size of about 6584 bp. The SIV H1N1 HA gene encodes a protein of 566 amino acids. 30 11.1.2 pLFl002: HA gene (modified form) cloned into the vector pLF999 The HA gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR reaction from the template pLFlOOl (Example 11.1.1) 3 5 with the aid of the following oligonucleotide pair: LF005 (30 mer) (SEQ ID NO 89) 5' TCCGCGGCCGCACATGCTAACAATTCCACA 3' and LF006 (32 mer) (SEQ ID NO 90) 5' TCCGCGGCCGCTTACATTGATTCTAGTTTCAC 3'. - 60 - The DNA fragment of 1515 bp obtained by digesting the PCR product with NotI is ligated with a fragment of 567 8 bp resulting from the digestion of pLF999 (Example 2) with NotI in order to generate the 5 plasmid pLFl.002 having a size of 7193 bp. The SIV H1N1 HA gene thus modified (intron II of the rabit [3-globin gene, tPA, A[TM+Cter]) encodes a protein of 530 amino acids. 10 11.2 Plasmids encoding the various forms of the SIV H1N1 strain NA 11.2.1 pLFlO03: NA gene (native form) cloned into the vector pVRl012 15 The cDNA of the NA gene of the H1N1 strain is synthesized from the corresponding viral RNA with the aid of the primer LF008 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF007 (30 mer) (SEQ ID NO 91) 20 5 ' CACCTGGTCGACATGAATCCAAATCAGAAG 3 ' and LF0 08 (30 mer) (SEQ ID NO 92) 5' CACCTGTCTAGACTACTTGTCAATGGTGAA 3'. The DNA fragment of 1416 bp obtained by digesting the PCR product with Sail and Xbal is ligated 25 with a fragment of 4881 bp resulting from the digestion of pVRl012 (Example 2) with Sail and Xbal in order to generate the plasmid pLF1003 having a size of about 6297 bp. The SIV HlNl NA gene encodes a protein of 469 3 0 amino acids. 11.2.2 pLFlO04: NA gene (modified form) cloned into the vector pLF999 The NA gene deleted for its transmembrane and 3 5 carboxy-terminal domains is synthesized by a PCR reaction from the template pLF1003 with the aid of the following oligonucleotide pair: LF009 (31 mer) (SEQ ID NO 93) 5' CACTACGAATTCACAAATTGGGAATCAAAAT 3' and - 61 - LF010 (30 mer) (SEQ ID NO 94) 5 ' AATTTGTGAATTCGCGGCCGCGGATCCGGT 3 ' . The DNA fragment of 12 07 bp obtained by digesting the PCR product with EcoRI is ligated with a 5 fragment of 567 8 bp resulting from the digestion of pLF999 (Example 2) with EcoRI in order to generate the plasmid pLFl004 having a size of about 6885 bp. The SIV H1N1 NA gene thus modified (intron II of the rabbit (3-globin gene, tPA, A[TM+Cter]) encodes a 10 protein of 431 amino acids. Example 12: Plasmids encoding the various forms of the swine influenza virus (SIV), strain H3N2, antigens The genes encoding the HA and NA antigens of 15 the type H3N2 swine influenza virus are obtained by RT-PCR from the viral RNA of the "Cotes du Nord 19 87" (cdn87) strain referenced by the World Health Organization (WHO) and available from the National Influenza Reference Center, Virology Laboratory, 8 20 avenue Rockfeller, 69008 Lyon, France. 12.1 Plasmids encoding the various forms of the SIV H3N2 strain HA 2 5 12.1.1 pLFl00 5: HA gene (native form) cloned into the vector pVRl012 The cDNA of the HA gene of the H3N2 strain is synthesized from the corresponding viral RNA with the aid of the primer LF012 and amplified by a PCR reaction 3 0 with the aid of the following oligonucleotide pair: LF011 (30 mer) (SEQ ID NO 95) 5 ' CTGCACGTCGACATGAAGACTGTCATTGCC 3 ' and LF012 (24 mer)(SEQ ID NO 96) 5 ' GATATCTCAGATGCAAATGTTGCA 3 ' . 3 5 The DNA fragment of 17 09 bp obtained by digesting the PCR product with EcoRV and Sail is ligated with a fragment.of 4893 bp resulting from the digestion of pVRl012 (Example 2) with EcoRV and Sail in - 62 - order to generate the plasmid pLF1005 having a size of about 6602 bp. The SIV H3N2 HA gene encodes a protein of 566 amino acids. 5 12.1.2 pLF1006: HA gene (modified form) cloned into the vector pLF999 The HA gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR 10 reaction from the template pLF1005 (Example 12.1-. 1) with the aid of the following oligonucleotide pair: LF013 (33 mer) (SEQ ID NO 97) 5' CACCGCGGATCCCTTCCAGAAAATGGCAGCACA 3' and LF014 (33 mer) (SEQ ID NO 98) 15 5' CACCGCGGATCCTTAGTCTTTGTATCCCGACTT 3'. The DNA fragment of 1542 bp obtained by digesting the PCR product with BamHI is ligated with a fragment of 567 8 bp resulting from the digestion of pLF999 (Example 2) with BamHI in order to generate the 20 plasmid pLF1006 having a size of about 7220 bp. The SIV H3N2 HA gene thus modified (intron II of the rabbit p-globin gene, tPA, A[TM+Cter]) encodes a protein of 53 8 amino acids. 25 12.2 Plasmids encoding the various forms of the SIV H3N2 strain NA 12.2.1 pLF1007: NA gene (native form) cloned into the vector pVR1012 3 0 The cDNA of the NA gene of the H3N2 strain is synthesized from the corresponding viral RNA with the aid of the primer LF016 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF015 (30 mer) (SEQ ID NO 99) 3 5 5 ' C AC TC AG AT ATC ATG AATC C AAAGC AAAAG 3 ' and LF016 (30 mer) (SEQ ID NO 100) 5 1 CACTCATCTAGATTATATAGGCATGAGATC 3 ' . The DNA fragment of 1414 bp obtained by digesting the PCR product with .EcoRV and Xbal is - 63 - ligated with a fragment of 4900 bp resulting from the digestion of pVR1012 (Example 2) with EcoRV and Xbal in order to generate the plasmid pLF1007 having a size of about 6314 bp. 5 The SIV H3N2 NA gene encodes a protein of 469 amino acids. 12.2.2 pLFlO08: NA gene (modified form) cloned into the vector pLF999 10 The NA gene deleted for its transmembrane and carboxy-terminal domains is synthesized by a PCR reaction from the template pLFlO05-• (Example 12.2.1) with the aid of the following oligonucleotide pair: LF017 (33 mer) (SEQ ID NO 101) 15 5' CACTACGGATCCTTCAAGCAATATGAGTGCGAC 3' and LF018 (33 mer) (SEQ ID NO 102) 5' CACTACGGATCCTTATGAAGTCCACCATACTCT 3'. The DNA fragment of 1221 bp obtained by digesting the PCR product with BamHI is ligated with a 20 fragment of 5678 bp resulting from the digestion of pLF999 (Example 2) with BamHI in order to generate the plasmid pLFl008 having a size of about 6899 bp. The SIV H3N2 NA gene thus modified (intron II of the rabbit [3-globin gene, tPA, A[TM+Cter]) encodes a 25 protein of 431 amino acids. Example 13: Plasmid encoding bovine GM-CSF The cDNA of the bovine GM-CSF gene is synthesized from the cellular RNA of "bovine blood 3 0 mononucleated cells with the aid of the primer LF065 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF054 (36 mer) (SEQ ID NO 103) 51 CATATCGTCGACATGTGGCTGCAGAACCTGCTTCTC 3' and 35 LF055 (34 mer) (SEQ ID NO 104) 51 CATGACCAGATCTTCACTTCTGGGCTGGTTCCCA 31. The DNA fragment of 43 7 bp obtained by digesting the PCR product with Sail and Bglll is ligated with a fragment of 4860 bp resulting from the - 64 - digestion of pVRl012 (Example 2) with Sail and Bglll in order to generate the plasmid pLFl032 (about 5297 bp) . The bovine GM-CSF gene encodes a protein of 143 amino acids. 5 Example 14: Plasmid encoding porcine GM-CSF The cDNA of the porcine GM-CSF gene is synthesized from the cellular RNA of porcine blood mononucleated cells with the aid of the primer LF067 10 and amplified by a PCR reaction with the aid of the following oligonucleotide pair: LF056 (36 mer) (SEQ ID NO 105) 5 ' CATATCGTCGACATGTGGCTGCAGAACCTGCTTCTC 3 ' and LF057 (37 mer) (SEQ ID NO 106) 15 5 ' CATGACCAGATCTTCACTTCTGGGCTGGTTCCCAGCA 3 ' . The DNA fragment of 44 0 bp obtained by digesting the PCR product with Sail and Bglll is ligated with a fragment of 4860 bp resulting from the digestion of pVRl012 (Example 2) with Sail and Bglll in 20 order to generate the plasmid pLFl033 (about 5300 bp) . The porcine GM-CSF gene encodes a protein of 144 amino acids. Example 15: Formulation of the vaccinal plasmids 25 The DNA solution containing one or more plasmids according to Examples 3 to 14 is concentrated by ethanolic precipitation as described in Sambrook et al. (19 89) . The DNA pellet is taken up in a 0.9% NaCl solution so as to obtain a concentration of 1 mg/ml. A 30 0.75 mM DMRIE-DOPE solution is prepared by taking up a lyophilisate of DMRIE-DOPE with an appropriate volume of sterile H2O. The formation of the plasmid DNA-lipid complexes is achieved by diluting, in equal parts, the 35 0.75 mM DMRIE-DOPE solution with the DNA solution at 1 mg/ml in 0.9% NaCl. The DNA solution is gradually introduced, with the aid of a seamed 2 6G needle, along the wall of the vial containing the cationic lipid solution so as to avoid the formation of foam. Gentle 10 - 65 - shaking is carried out as soon as the two solutions have been mixed. A composition comprising 0.375 mM of DMRIE-DOPE and 500 ug/ml of plasmid is finally obtained. It is desirable for all the solutions used to be at room temperature for all the operations described above. The DNA/DMRIE-DOPE complex formation is allowed to take place at room temperature for 3 0 minutes before immunizing the animals. Example 16: Immunization of bovines against BHV-1 12 bovines are randomized into'3 groups of 4 s. Group 1 constitutes the control animal group.. A mixture of vaccinal plasmids pPB281 (encoding 15 BHV-1 gB in a A[TM-Cter] form, Example 3.1.2), pPB292 (encoding BHV-1 gC in a A[TM-Cter] form, Example 3.2.2) and pPB284 (encoding BHV-1 gD in a A[TM-Cter] form, Example 3.3.2) is administered to the animals of Group 2. 2 0 The same mixture as that in Group 2, but formulated with DMRIE-DOPE as is described in Example 15, is administered to the animals of Group 3. An injection of 10 ml, by the intramuscular route, is performed on each bovine with the aid of 2 5 syringes equipped with needle, and is repeated 21 days later. The total mass of each plasmid used during each immunization is 1500 jag. Persons skilled in the art possess the necessary competence to adjust the volume or the 3 0 concentration according to the plasmid dose required. Monitoring of the serological response induced by the two mixtures of vaccine plasmids expressing the BHV-1 gB, gC and gD antigens is carried out over a period of 35 days after the first vaccination. 3 5 The results are presented in the table which follows: - 66 - 5 Plasmids Formulation Antigens Dose SN at D28 SN at D35 control 0.2 +/- 0.0 0.2 +/-0.0 pPB2 81 pPB292 pPB294 gB A[TM-Cter] gC A[TM-Cter] gD A[TM-Cter] 1500 jig 1500 pg 1500 jig 1.0 +/- 0.5 1.2 +/- 0.8 pPB281 pPB292 pPB294 DMRIE-DOPE gB A[TM-Cter] gC A[TM-Cter] gD A[TM-Cter] 1500 pg 1500 pg 1500 pg 2.1 +/- 0.6 2.7 +/- 0.6 Example 17: Immunization of pigs against PRV 15 pigs, about 7 weeks old, are randomized into 3 groups of 5 animals. 10 Group 1 constitutes the control animal group. A mixture of vaccinal plasmids pNS009 (encoding PRV gB in a tPA A[TM-Cter] form, Example 8.1.3), pNS012 (encoding PRV gC in a tPA A[TM-Cter] form, Example 8.2.3) and pPB23 8 (encoding PRV gD in a tPA A[TM-Cter] 15 form, Example 8.3.3) is administered to the animals of Group 2. The same mixture as that in Group 3 but formulated with DMRIE-DOPE as is described in Example 15 is administered to the animals of Group 4 so as to 20 obtain a final DMRIE-DOPE concentration of 0.0535 mM. 3 50 Jig of each plasmid necessary for these vaccination protocols are mixed in a final volume- of 14 ml. An injection of 2 ml, by the intramuscular 25 route, is performed, with the aid of syringes equipped with needle on each pig, and is repeated 21 days later. The pigs are challenged at D3 5 by nasal administration of 2 ml of a solution of PRV strain NIA3 challenge virus in an amount of 1 ml per nostril and 30 having a titre of 107'76 CCID50 per ml. - 67 - Monitoring of the weight (in kg) of each animal is carried out over a period of 42 days after the first vaccination. The relative weight gain (G7) is calculated for each animal during the 7 5 days period which immediately follows the challenge. It is the difference between the weight at day 7 (D7) and that at challenge day (DO), divided by the weight at challenge day, and daily expressed as a percentage : 10 (weight at D7 - weight at DO). 100 / (weight at DO. 7) AG7 is the difference between the mean values of relative weight gains of vaccinated animals and controls. The results are presented in the table which follows : Plasmids Formulation Antigens Dose Mean weight at D35 Mean weight at D42 AG7 Control 25.3 +/- 6.2 22.0 +/- 5.0 PNS0 09 PNS012 pPB23 8 gB A[TM-Cter]tPA gC A[TM-Cter]tPA gD A[TM-Cter]tPA 350 |lg 3 5 0 (J.g 350 (Xg 25.3 + /- 4.8 26.1 +/- 4.7 2 .46 pNS0 09 PNS012 PPB23 8 DMRIE-DOPE gB A[TM-Cter]tPA gC A[TM-Cter]tPA gD A[TM-Cter]tPA 3 50 \lg 3 50 \lg 3 50 |ig 23.8 +/- 4.5 26.2 +/- 4.9 3 .41 - 69 - It should be clearly understood that the invention defined by the appended claims is not limited to the specific embodiments indicated in the description above, but encompasses the variants which depart neither from the scope nor the spirit of the present invention. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> - 70 -Claims

1. DNA vaccine against a pathogen affecting- farm animals, in particular bovines or porcines, comprising a plasmid containing a nucleotide sequence encoding an immunogen of a pathogen of the animal species considered, under conditions allowing the in vivo expression of this sequence, and a cationic lipid containing a Quaternary ammonium salt, of formula ch3 ri - o - ch2 - ch- ch2 - n -—r2-x or, ch3 in which Ri is a saturated or unsaturated linear aliphatic radical having 12 to 18 carbon atoms, R2 is another aliphatic radical containing 2 or 3 carbon atoms, and X a hydroxyl or amine group, this lipid being preferably DMRIE (N-(2-hydroxyethvl)-N,N-dimethyl-2,3-bis (tetradecyloxy)-1 -propaneammonium.

2. Vaccine according to Claim 1, characterized in that it also comprises DOPE (dioleoylphosphatidyl-ethanolamine),

3. Vaccine according to Claim 1 or 2, therein it comprises, in addition", a GM-CSF protein of the animal species considered.

4. Vaccine according to Claim 1 .or 2, wherein it comprises, in addition, an expression vector containing the gene encoding the GM-CSF protein of the animal species considered, under conditions allowing the in vivo expression of this sequence.

5. Vaccine according to Claim 4, wherein the expression vector is a plasmid.

6. Vaccine according to any one of Claims 1 to 5, wherein the nucleotide sequence encoding a pathogen immunogen is the sequence of a gene from which the part encoding the transmembrane domain has 'been deleted. intellectual property OFFICE OF N.7. \ 6 jun m RECEIVED - 71 -

7. Vaccine according to any one of Claims 1 to 6, whecein che plasmid containing the nucleotide sequence encoding a pathogen immunogen also contains a nucleotide sequence encoding a heterologous 5 signal sequence, preferably a tPA.

8. Vaccine according to any one of Claims 1 to 7, wherein the plasmid containing the nucleotide sequence encoding a pathogen immunogen also contains a stabilizing intron. 10

9. Vaccine according to Claim 7, wherein the intron is intron II of the rabbit beta-globin gene.

10. Vaccine according to one of Claims 1 to 5, wherein * it comprises . a nucleotide 15 sequence of BHV-1 (bovine herpesvirus type 1).

11. Vaccine according to Claim 10, wherein it comprises the sequence of the gB gene optimized by a signal sequence, in particular that of the tPA signal of human origin, in place of the sequence of the 20 signal peptide of the glycoprotein gB, and/or by the deletion of the DNA fragment encoding the transmembrane domain of gB.

12. Vaccine according to Claim 10, wherein it comprises the sequence of the gC gene optimized 25 by a signal sequence, in particular that of the tPA signal of human origin, in place of the sequence of the signal peptide of the glycoprotein gC, and/or by the deletion of the DNA fragment encoding the transmembrane domain of gC. ' 30

13. Vaccine according to Claim 10, wherein it comprises the sequence of the gD gene optimized by a signal sequence, in particular that of the tPA signal of human origin, in place of the sequence of the signal peptide of the glycoprotein gD, and/or by the 3 5 deletion of the DNA fragment encoding the transmembrane domain of gD.

14. Vaccine according to Claim 10, wherein it comprises DMRIE-DOPE, an expression plasmid encoding the BHV-1 gB antigen optimized by the deletion INTELLECTUAL property office OF N.Z. 16 jun 2004 - 72 - of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part, a second expression plasmid encoding the BHV-1 gC antigen optimized by the deletion of the fragment of 5 the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part, and a third expression plasmid encoding the BHV-1 gD antigen optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain 10 and the contiguous C-terminal part.

15. Vaccine according to one of Claims 1 to 5, wherein! it comprises a . nucleotide sequence of BRSV (bovine respiratory syncitial virus).

16. Vaccine according to Claim 15, wherein 15 it comprises the sequence of the BRSV F gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the signal sequence of the F protein of BRSV, and/or by the deletion of the DNA fragment encoding the transmembrane 2 0 domain of F.

17. Vaccine according to Claim 15, wherein it comprises the sequence of the BRSV G gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the 25 signal sequence of the G glycoprotein of BRSV, and/or by the deletion of the DNA fragment encoding the transmembrane domain of G.

18. Vaccine according to Claim 15, wherein it comprises DMRIE-DOPE, an expression plasmid 3 0 encoding the F antigen of BRSV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of F, and by the deletion of the fragment of the nucleotide sequence of F encoding the transmembrane domain and the contiguous 3 5 C-terminal part, and a second expression plasmid encoding the G antigen of BRSV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of G, and by the deletion of the fragment of the nucleotide sequence encoding the intellectual property office of n.z. 16 jun 2004 - 13 - transmembrane domain of G and the contiguous C-terminal part.

19. Vaccine according to one of Claims 1 to 5, wherein it comprises a nucleotide 5 sequence of BVDV.

20. Vaccine according to Claim 19, wherein it comprises the sequence of the BVDV EO gene optimized by the addition of a signal sequence, in particular that of the tPA of human origin, upstream of 10 the nucleotide sequence encoding the EO protein, and/or by the insertion of an intron, in particular intron II of the rabbit beta-globin gene 'upstream of the nucleotide sequence encoding EO.

21. Vaccine according to Claim 19, wherein 15 it comprises the sequence of the E2 gene optimized by the addition of a signal sequence, in particular that of the tPA of human origin, upstream of the nucleotide sequence encoding the E2 protein, and/or by the deletion of the DNA fragment encoding the 20 transmembrane domain of E2, and/or by the insertion of an intron, in particular intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding E2.

22. Vaccine according to Claim 19, wherein 25 it comprises DMRIE-DOPE, an expression plasmid encoding the EO antigen of BVDV optimized by the insertion of the signal sequence of the human tPA upstream of EO and by the insertion of intron II of the rabbit beta-globin gene upstream of EO, and a second 3 0 plasmid encoding the E2 antigen of BVDV optimized by the insertion of the signal sequence of the human tPA upstream of E2, by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain of E2 and by the insertion of intron II of the rabbit 3 5 beta-globin gene upstream of E2.

23. Vaccine according to one of Claims 1 to 5, wherein it comprises a nucleotide sequence of bPI-3. INTELLECTUAL property i office of n.z. 16 jun 2004 RECEIVED - 74 -

24. Vaccine according to Claim 23, wherein it comprises the sequence of the bPI-3 HN gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the 5 ' signal sequence of HN. (hemagglutinin-neuraminidase) and/or by the deletion of the DNA fragment encoding the transmembrane domain of HN. and/or by the insertion of an intron. in particular of intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding HN. 10

25. Vaccine according to Claim 23, wherein it comprises the sequence of the bPI-3 F gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the signal sequence of F, and/or by the deletion of the DNA 15 fragment encoding the transmembrane domain of F, and/or by the insertion of an intron, in particular of intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding F.

26. Vaccine according to Claim 23, wherein 20 it comprises DMRIE-DOPE, an expression plasmid encoding the HN antigen of bPI-3 optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of HN, by the deletion of the fragment of the nucleotide sequence of HN encoding 2 5 the transmembrane domain and the contiguous C-terminal part and by the insertion of intron II of the rabbit beta-globin gene upstream of HN, and a second expression plasmid encoding the F antigen of bPI-3 optimized by the insertion of the signal sequence of 3 0 the human tPA in place of the signal sequence of F, by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain of F and the contiguous C-terminal part and by the insertion of intron II of the rabbit beta-globin gene upstream of F. 35

27. Vaccine according to one of Claims 1 to 5, wherein ^ comprises a nucleotide sequence of PRV.

28. Vaccine according to Claim 27, wj,ei?ein it comprises the sequence of the gB gene optimized INTELLECTUAL PROPERTY office of n .1. 1 6 JUN 200^ RECEIVED - 75 - by substitution, by a signal sequence, in particular that of the tPA signal of human origin, of the sequence of the signal peptide of the gB glycoprotein, and/or by the deletion of the DNA fragment encoding the transmembrane domain of gB.

29. Vaccine according to Claim 27, wherein it comprises the sequence of the gC gene optimized by substitution, by a signal sequence, in particular that of the tPA signal of human origin, of the sequence of the signal peptide of the gC glycoprotein, and/or by-the deletion ■ of the DNA fragment encoding the transmembrane domain of gC.

30. Vaccine according to Claim 27, wherein it comprises the sequence of the gD gene optimized by substitution, by a signal sequence, in particular that of the tPA signal of human origin, of the sequence of the signal peptide of the gD glycoprotein, and/or by the deletion of the DNA fragment encoding the transmembrane domain of gD.

31. Vaccine according to Claim. 27, wherein it comprises DMRIE-DOPE, an expression plasmid encoding the gB antigen of PRV optimized by the deletion of the fragment of the nucleotide sequence encoding' the transmembrane domain and of the contiguous C-terminal part, a second expression plasmid encoding the gC antigen of PRV optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and of the contiguous C-terminal part, and a third expression plasmid encoding the gD antigen of PRV optimized by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and of the contiguous C-terminal part.

32. Vaccine according to one of Claims 1 to 5, wherein it comprises a nucleotide sequence of PRRSV.

33. Vaccine according to Claim 32, wherein it comprises a nucleotide sequence of the ORF3 gene optimized by substitution, by a signal sequence, intellectual property OFFICf OF N7. t 6 jun 2004 received - 76 - in particular that of the tPA signal of human origin, or the sequence of the signal peptide of the protein encoded by 0RF3, and/or by the deletion of the DNA fragment encoding the transmembrane domain of 0RF3. 5

34. Vaccine according to Claim 32, wherein it comprises a nucleotide sequence of the 0RF5 gene optimized by substitution, by a signal sequence, in particular that of the tPA signal of human origin, or the sequence of the signal peptide of the protein 10 encoded by ORF5, and/or by the deletion of the DNA fragment encoding the transmembrane domain of ORF5.

35. Vaccine according to Claim 32; -gfobrein it comprises a nucleotide sequence of the ORF6 gene optimized by substitution, by a signal sequence, 15 in particular that of the tPA signal of human origin, or the sequence of the signal peptide of the protein encoded by ORF6, and/or by the deletion of the DNA fragment encoding the transmembrane domain of ORF6.

36. Vaccine according to Claim 32, wherein 2 0 it comprises DMRIE-DOPE, an expression plasmid encoding the 0RF3 antigen of PRRSV, a second expression plasmid encoding the ORF5 antigen of PRRSV optimized by substitution of the signal sequence of ORF5 by the human tPA signal peptide sequence and by the deletion 25 of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part, and a third expression plasmid encoding the ORF6 antigen of PRRSV optimized by the substitution of the signal sequence of 0RF6 by the human tPA signal peptide 3 0 sequence and by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain and the contiguous C-terminal part.

37. Vaccine according to one of Claims 1 to 5, wherein it comprises a nucleotide 35 sequence of SIV.

38. Vaccine according to Claim 37, wherein it comprises a nucleotide sequence of the HA gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the intellectual property OFFICE OF N 7. 1 6 jun 2004 D f fi rlvrn - 77 - signal sequence of HA, and/or by the deletion of the DNA fragment encoding the transmembrane domain of HA, and/or by the insertion of an intron, in particular of intron II- of the rabbit beta-globin gene upstream of 5 the nucleotide sequence encoding HA.

39. Vaccine according to Claim 37, wherein it comprises a nucleotide sequence of the NA gene optimized by substitution, by a signal sequence, in particular that of the tPA of human origin, of the 10 signal sequence of NA, and/or by the deletion of the DNA fragment encoding the transmembrane domain of NA, and/or by the insertion of an intron,--in particular of intron II of the rabbit beta-globin gene upstream of the nucleotide sequence encoding NA. 15

40. Vaccine according to Claim 37, wherein it comprises DMRIE-DOPE, an expression plasmid encoding the HA antigen of SIV optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of HA, by the deletion of 2 0 the fragment of the nucleotide sequence of HA encoding the transmembrane domain and the contiguous C-terminal part, and by the insertion of intron II of the rabbit beta-globin gene upstream of HA, and a second expression plasmid encoding the NA antigen of SIV 25 optimized by the insertion of the signal sequence of the human tPA in place of the signal sequence of NA, by the deletion of the fragment of the nucleotide sequence encoding the transmembrane domain of NA and the contiguous C-terminal part, and by the insertion of 3 0 intron II of the rabbit beta-globin gene upstream of NA.

41. DNA vaccine against a pathogen affecting farm animals, in particular bovines or porcines. substantially as herein defined with reference to the accompanying Examples. END OF CLAIMS intellectual property OFFICE OF N.Z. 16 jun m received </div>