Abstract:
The present invention relates to vaccines for avian use which are based on live recombinant avian herpesviruses, in particular the Marek&#39;s disease viruses including HVT virus (herpesvirus of turkey), in which has been inserted, by genetic recombination, at least one nucleotide sequence which encodes and expresses an antigenic polypeptide of an avian pathogen under conditions which ensure immunization leading to efficient protection of the vaccinated animal against the pathogen. In one embodiment, the antigenic polypeptide is inserted in the UL43 gene under the control of the CMV immediate early promoter. The vaccines of the present invention are advantageous over previously used vaccines in that they can be used to ensure total protection of animals against Gumboro disease and to immunize chicks as young as one-day old without secondary effects, and only require low doses.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to vaccines for avian use which are based on live recombinant avian herpesviruses namely, and in particular, Marek&#39;s disease virus (MDV) and, more especially, HVT virus (herpesvirus of turkey), in which has been inserted, by genetic recombination, at least one nucleotide sequence which encodes, and expresses, an antigenic polypeptide of an avian pathogen under conditions which ensure an immunization leading to efficient protection of the vaccinated animal against the said pathogen. It also applies to infectious laryngotracheitis virus (ILTV) and to duck herpesvirus. 
     2. Prior Art 
     A certain number of recombinant avian viral vectors have already been proposed for the purpose of vaccinating birds against avian pathogens, especially viral pathogens, including the viruses of Marek&#39;s disease (MDV), of Newcastle disease (NDV), of infectious laryngotracheitis (ILTV), of Gumboro disease (infectious bursal disease, IBDV), of infectious bronchitis (IBV) and of avian anemia (CAV). 
     The viral vectors employed include avipox viruses, in particular fowlpox (EP-A-0 517 292; H.-G. Heine et al., Arch. Virol. 1993, 131: 277-292; D. B. Boyle et al., Veterinary Microbiology 41, 1994, 173-181; C. D. Bayliss et al., Arch. Virol. 1991, 120: 193-205), Marek&#39;s viruses, especially serotypes 2 and 3 (HVT) (WO-A-87 04463; WO-A-89 01040; WO-A-93 25665; EP-A-0 513 921; J. McMillen, Poultry Condemnation Meeting, October 1994, 359-363; P. J. A. Sondermeijer et al., Vaccine 1993, 11, 349-357; R. W. Morgan et al., Avian Diseases 36: 858-870, 1992 and 37: 1032-1040, 1993) and also ILTV virus and avian adenovirus. 
     When used for vaccination, these recombinant viruses induce varying, in general weak or partial, levels of protection, even if a substantial degree of protection can be demonstrated in rare specific instances. 
     Gumboro disease virus, or IBDV virus, is one of the most difficult to protect against using live recombinant avian vaccines. Thus, although effective conventional live attenuated or inactivated vaccines against this disease are available, no live recombinant vaccine has yet been demonstrated to have suitable efficacy. 
     The genome of Gumboro disease virus consists of a double-stranded RNA. The largest segment (segment A) encodes a polyprotein of 115 kDa, which is secondarily cleaved into three proteins, VP2 (41 kDa), VP4 (28 kDa) and VP3 (32 kDa). VP4 would appear to be a protease which is involved in the maturation of the 115 kDa polyprotein. The position of the cleavage site between VP2 and VP4 has only been determined approximately (M. Jagadish, J. Virol. 1988, 62, 1084-1087). The VP2 protein is an immunogen which induces neutralizing antibodies and protection against Gumboro disease. 
     It has already been proposed to insert genes encoding immunogenic IBDV proteins into various live vectors: EP-A-0 517 292 (insertion of sequences encoding VP2 or the polyprotein into an avipox); C. D. Bayliss 1991, H.-G. Heine 1993 and D. B. Boyle 1994 above (VP2 in fowlpox); WO-A-90 02802 (MDV vector); WO-A-90 02803 (HVT and ILTV vectors); French patent applications Nos. 90 03105, 90 11146 and 92 13109 (HVT vector). 
     Patent applications WO-A-89 01040 and WO-A-93 25655 describe the construction of an HVT avian viral vector in which a sequence permitting expression of the native VP2 protein of the IBDV virus, known as the prime polypeptide candidate for vaccinating against Gumboro disease, has been inserted into the XhoI insertion site which is present in the HVT UL43 gene, identified in the first of these two applications under the designation BamHI fragment #16, under the control of an exogenous promoter. However, despite obtaining a native VP2 protein, it was not possible to obtain any induction of neutralizing antibodies or protection when the vaccinated animals were challenged with virulent IBDV virus. 
     This is why the idea of using this site has not been pursued, and it has instead been proposed, in WO-A-93 25655, to insert sequences which permit expression of the IBDV VP2 protein, still under the control of an exogenous promoter, into the unique StuI site of the HVT US2 gene. The expression of the VP2 protein was characterized in vitro, without demonstrating any activity or protection in vivo. It may also be noted that insertions of other genes in this US2 StuI site, namely the MDV gB gene, accompanied or not accompanied by the gC gene (termed gA in this earlier document), and linked to its own promoter, or the gB and gC genes together with the F gene of NDV linked to the immediate early (IE) HCMV promoter, or the gB and gC genes together with the NDV HN gene linked to the PRY promoter gX, have made it possible to obtain protection against challenges with the corresponding virulent viruses. Similarly, protection is reported for constructs in which the gB and gD genes of the ILTV virus are inserted into this same site. These results contrast with the total absence of protection, and the naive assumptions, in application WO-A-89 01040. 
     Various promoters, including those which are generally available commercially, have been used in the different constructs of the prior art, including the PRV gX promoter, the HCMV IE (human CMV immediate early) promoter, the herpes simplex alpha-4 promoter, the FPV P.E/L promoter (fowlpox promoter) (H. Heine et al., 1993, Arch. Virol. 131, 277-292), P7.5 (C. Bayliss et al., 1991, Arch. Virol. 120, 193-205) and P11 (D. Boyle et al., 1994, Vet. Microb. 41, 173-181) promoters of vaccinia virus, originating from the LTR sequence of RSV (Rous sarcoma virus) and the early SV40 promoter, as well as the MDV or HVT promoters, such as the promoters of the genes gB, gC, TK, RR2, etc., without any consistent pattern emerging, especially as regards constructs in HVT. The sequences of certain promoters can inhibit the replication of the HVT or MDV recombinant vectors (D. R. Marshall et al., J. Meth. 1992, 40, 195-204 and Virology 1993, 195, 638-648). Among the cited promoters, a certain number, such as, for example, SV40, LTR RSV and PRV gX, have displayed a certain degree of efficacy, as have certain native promoters of certain genes of the Marek&#39;s viruses, especially serotype 3. 
     There still exists, therefore, due to the technical and economic constraints imposed by inactivated vaccines and the safety problems associated with the use of live attenuated vaccines, the need for a live recombinant vaccine which is effective against Gumboro disease virus (IBDV). Such a vaccine, which is based on a recombinant HVT vector and which would be truly effective against Gumboro disease, could, moreover, open the way to vaccines which were very effective against other avian diseases, in view of the fact that it is particularly difficult to achieve protection against Gumboro disease. 
     SUMMARY OF THE INVENTION 
     The invention has now, surprisingly, made it possible to develop an HVT vector-based live recombinant vaccine in which at least one sequence encoding the IBDV VP2 protein is inserted and which ensures total protection of animals against Gumboro disease, namely protection against death and against lesions of the bursa of Fabricius. Furthermore, the efficacy of this vaccine proves to be such that it has become possible even to vaccinate one-day-old chicks effectively and without any secondary effects (especially the absence of local lesions at the point of injection and the absence of any lesion in the bursa of Fabricius), something which was not even possible using inactivated vaccines. In addition, the doses which are required are astonishingly low. 
     The subject of the present invention is a live recombinant avian vaccine which comprises, as vector, an avian herpesvirus which includes at least one nucleotide sequence which encodes, and expresses, an antigenic polypeptide of an avian pathogen and which is inserted in the UL43 gene under the control of the CMV immediate early promoter. 
     The avian herpesviruses according to the invention are preferably the Marek&#39;s disease viruses, especially HVT, infectious laryngotracheitis virus ILTV and duck herpesvirus. The Marek&#39;s disease viruses and, more particularly, HVT virus are preferred. 
     Insertion into the UL43 gene is understood to mean both simple insertion into this site without deleting it and insertion following total or partial deletion. Insertion after partial deletion is preferred. 
     CMV immediate early (IE) promoter is understood to mean the fragment given in the examples as well as its subfragments which retain the same promoter activity. 
     The CMV IE promoter can be the human promoter (HCMV IE) or the murine promoter (MCMV IE), or else a CMV IE promoter of different origin, for example from the rat or from the guinea-pig. 
     The nucleotide sequence which is inserted into the Marek vector in order to be expressed can be any sequence encoding an antigenic polypeptide of an avian pathogen, which polypeptide is capable, once expressed under the favorable conditions procured by the invention, of ensuring an immunization which leads to effective protection of the vaccinated animal against the pathogen. It will be possible, therefore, under the conditions of the invention, to insert nucleotide sequences which encode antigens of interest for a given disease. In particular, the characteristics of the recombinant according to the invention permit vaccination in ovo and vaccination of 1-day old-chicks, as well as vaccination of older chicks and adults. 
     The typical case of the invention is the insertion of a nucleotide sequence which expediently encodes the VP2 polypeptide of the IBDV virus. In this way, a live recombinant vaccine is obtained which ensures, in addition to protection against Marek&#39;s disease, total protection against Gumboro disease. If desired, a sequence encoding another IBDV antigen, such as VP3 or even the polyprotein VP2+VP4+VP3, can also be inserted, with these other possibilities not being preferred. 
     The recombinant vaccine against Gumboro disease will preferably be administered within the range of from 10 to 10 4  PFU/dose, more especially of from 10 2  to 10 3  PFU/dose, and even between 10 and 10 2  PFU/dose, approximately. 
     Other preferred cases of the invention are the insertion of nucleotide sequences which encode antigens of Marek&#39;s disease virus, in particular genes gB, gC, and gH+gL (WO-A-90 02803), of Newcastle disease virus, in particular genes F and HN, of infectious bronchitis virus (IBV), in particular genes S and M (M. Binns et al., J. Gen. Virol. 1985, 66, 719-726; M. Boursnell et al., Virus Research 1984, 1, 303-313), of avian anemia virus (CAV), in particular VP1(52 kDa)+VP2(24 kDa) (N. H. M. Noteborn et al., J. Virol. 1991, 65, 3131-3139) and of infectious laryngotracheitis virus (ILTV), in particular genes (WO-A-90 02802), gC, gD and gH+gL. 
     The doses will preferably be the same as those which are indicated for the Gumboro vaccine. 
     According to an advantageous development of the invention, the CMV IE promoter is linked to another promoter in a head-to-foot orientation, making it possible to insert two nucleotide sequences into the insertion site, one under the control of the CMV IE promoter and the other under the control of the linked promoter. This construct is remarkable for the fact that the presence of the CMV IE promoter, and especially of its enhancer part, activates the transcription which is induced by the linked promoter. A preferred linked promoter is the Marek 1.8 RNA promoter, whose transcriptional activity is found to be increased 4.4 fold under these conditions. 
     The typical case of the invention is a vaccine comprising a nucleotide sequence which encodes IBDV VP2 under the control of CMV IE and a nucleotide sequence which encodes an antigen of another avian disease, especially those cited above, under the control of another promoter. 
     Two CMV IE promoters of different origins can also be arranged in a head-to-foot orientation. 
     It will also be possible to use the 1.8 RNA promoter on its own in place of the CMV IE promoter, especially for vaccines against Marek&#39;s disease, Newcastle disease, infectious laryngotracheitis, infectious bronchitis and avian anemia. 
     The present invention also relates to a multivalent vaccine formulation which comprises, in a mixture or to be mixed, at least two live recombinant avian vaccines such as defined above, with these vaccines containing different inserted sequences, especially from different pathogens. 
     The present invention also relates to a method of avian vaccination which comprises administering a live recombinant vaccine or a multivalent vaccine formulation such as defined above. It particularly relates to such a method for vaccinating in ovo, for vaccinating chicks of 1 day of age or older, and for vaccinating adults. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     The invention will now be described in more detail with the aid of non-limiting exemplary embodiments and by reference to the drawings in which: List of the drawings and of the sequences of the constructs in the UL43 site 
     FIG. 1: Sequence of the HVT U s  gI region 
     FIG. 2: Construction of the plasmids pRD022 and pRD027 
     FIG. 3: Construction of the plasmids pRD023 and pRD029 
     FIG. 4: plasmid pCMVβ 
     FIG. 5: plasmid pEL022 
     FIG. 6: plasmid pEL023 
     FIG. 7: plasmid pEL024 
     FIG. 8: plasmid pEL025 
     FIG. 9: Sequence of the HVT BamHI M fragment and ORF UL43 
     FIG. 10: Construction of the plasmids pMB010 and pMB016 
     FIG. 11: plasmid pEL026 
     FIG. 12: plasmid pEL027 
     FIG. 13: plasmid pEL042 
     FIG. 14: plasmid pCD002 
     FIG. 15: plasmid pCD009 
     FIG. 16: plasmid pEL068 
     FIG. 17: plasmid pEL070 
     FIG. 18: plasmid pEL072 
     FIG. 19: plasmid pCD011 
     FIG. 20: plasmid pCD012 
     FIG. 21: Sequence of the NDV HN gene 
     FIG. 22: plasmid pEL028 
     FIG. 23: plasmid pEL029bis 
     FIG. 24: plasmid pEL030 
     FIG. 25: plasmid pEL032 
     FIG. 26: plasmid pEL043 
     FIG. 27: plasmid pEL033 
     FIG. 28: plasmid pEL034 
     FIG. 29: plasmid pEL044 
     FIG. 30: 1.8 kbp RNA promoter sequence 
     FIG. 31: plasmid pBS002 
     FIG. 32: plasmid pEL069 
     FIG. 33: plasmid pEL080 
     FIG. 34: plasmid pEL081 
     FIG. 35: plasmid pEL082 
     FIG. 36: plasmid pEL096 
    
    
     List of the SEQ ID sequences of the constructs in the UL43 site 
     SEQ ID NO. 1 Oligonucleotide RD045 
     SEQ ID NO. 2 Oligonucleotide pBRPst- 
     SEQ ID NO. 3 Sequence of the HVT U s  gI region 
     SEQ ID NO. 4 Oligonucleotide RD048 
     SEQ ID NO. 5 Oligonucleotide RD049 
     SEQ ID NO. 6 Sequence of the HVT BamHI M fragment 
     SEQ ID NO. 7 Oligonucleotide MB014 
     SEQ ID NO. 8 Oligonucleotide MB015 
     SEQ ID NO. 9 Oligonucleotide MB070 
     SEQ ID NO. 10 Oligonucleotide MB071 
     SEQ ID NO. 11 Oligonucleotide CD001 
     SEQ ID NO. 12 Oligonucleotide CD002 
     SEQ ID NO. 13 Oligonucleotide CD003 
     SEQ ID NO. 14 Oligonucleotide CD004 
     SEQ ID NO. 15 Sequence of the NDV EN gene 
     SEQ ID NO. 16 Oligonucleotide EL071 
     SEQ ID NO. 17 Oligonucleotide EL073 
     SEQ ID NO. 18 Oligonucleotide EL074 
     SEQ ID NO. 19 Oligonucleotide EL075 
     SEQ ID NO. 20 Oligonucleotide EL076 
     SEQ ID NO. 21 Oligonucleotide EL077 
     SEQ ID NO. 22 Sequence of the 1.8 kbp RNA promoter 
     SEQ ID NO. 23 Oligonucleotide MB047 
     SEQ ID NO. 24 Oligonucleotide MB048 
     SEQ ID NO. 25 Oligonucleotide MB072 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     All the plasmid constructions were carried out using standard molecular biological techniques described by Sambrook J. et al. (Molecular Cloning: A Laboratory Manual. 2nd Edition. Cold Spring Harbor Laboratory. Cold Spring Harbor. N.Y. 1989). All the restriction fragments which were employed for the present invention were isolated using the &#34;Geneclean&#34; kit (BIO101 Inc. La Jolla, Calif.). 
     The virus which was used as parent virus is the turkey herpesvirus (HVT) strain FC126, which was isolated by Dr. Witter of the Regional Poultry Research Laboratory (USDA, East Lansing, Mich.) in a 23-week old flock of turkeys (Witter R. L. et al. Am. J. Vet. Res. 1970. 31. 525-538). The conditions for culturing this virus are those described elsewhere (French patent application 90 03105). 
     EXAMPLE 1 
     Extraction of the DNA of Marek&#39;s disease Virus 
     The whole blood of a chicken which was challenged at 7 days with the strain MDV RB1B is collected with a syringe on to anticoagulant (100 IU/ml heparin solution) at 14 days after infection. The blood is then centrifuged at 30 g for 15 minutes and at ambient temperature. The plasma as well as the buffy coat are removed and diluted in sterile PBS up to a final volume of 10 ml. After centrifuging at 150 g for 15 minutes, the cell pellet is resuspended in 2 ml of 199 culture medium (Gibco-BRL Cat#042-01183M) containing 2% fetal calf serum (FCS). The total DNA of the infected lymphocytes is then extracted using the technique described by R. Morgan et al. (Avian Diseases. 1990. 34. 345-351) and can be used directly as a template for PCR experiments. In order to clone genomic fragments of the MDV virus, the RB1B strain was cultured on CEC and the viral DNA was prepared from viral particles which were purified as described by Lee Y. et al. (J. Gen. Virol. 1980. 51. 245-253). 
     EXAMPLE 2 
     Preparation of the Genomic DNA of the MCMV (Mouse Cytomegalovirus) Virus 
     The Smith MCMV virus strain was obtained from the American Type Culture Collection, Rockville, Md., USA (ATCC No. VR-194). This virus was cultured on Balb/C mouse embryo cells, and the viral DNA of this virus was prepared as described by Ebeling A. et al. (J. Virol. 1983. 47. 421-433). 
     EXAMPLE 3 
     Preparation of the Genomic DNA of the HVT Virus for the Transfection Experiments 
     The viral DNA which was used for the transfection experiments was prepared, in accordance with the technique described by R. Morgan et al. (Avian Diseases. 1990. 34. 345-351), using a culture of secondary CEC (CEC II) which was infected with the HVT virus FC126 strain. 
     Construction of the recombinant viruses 
     EXAMPLE 4 
     Construction and Isolation of vHVT1 
     The construction of the donor plasmid pGH010, and the isolation and purification of the recombinant virus vHVT1 were described in French patent application 92.13109. This recombinant HVT virus contains the gene encoding the VP2 capsid protein of Gumboro disease virus (IBDV virus) placed under the control of the promoter of the RR2 gene of the HVT virus. In this recombinant virus, the VP2 gene was inserted in place of the HVT RR2 gene. 
     EXAMPLE 5 
     Construction of the Donor Plasmid pEL025 and Isolation of vHVT2 
     5.1. Construction of the donor plasmid pEL025 
     The 29 kbp BamHI A fragment of the HVT virus strain FC126 (Igarashi T. et al. Virology. 1989. 70. 1789-1804) was cloned into the BamHI site of the vector pBR322 to give the plasmid pRD001. Plasmid pRD001 was digested with PstI and the 2.8 kbp and 5.7 kbp PstI--PstI fragment were cloned into the PstI site of vector pBR322 to give the plasmids pRD006 and pRD007, respectively. Plasmid pRD006 was digested with PstI and SacI in order to isolate the PstI/SacI fragment of 340 bp (fragment A). 
     A PCR was carried out using the oligonucleotides: 
     RD045 (SEQ ID NO. 1) 5&#39; TGCTGGTACCGTCGACAAGCTTGGATCCGTGCAGATAACACGTACTGGC 3&#39; pBRPst- (SEQ ID NO. 2) 5&#39; CATGTAACTCGCCTTGATC 3&#39; 
     and the pRD007 template, in order to obtain a fragment of 550 bp (positions 339 to 831 in FIG. 1 (SEQ ID NO. 3) (positions 6491 to 6980 in the HVT U s  sequence (Zelnik V. et al. J. Gen. Virol. 1993. 74. 2151-2162). The PCR fragment of 520 bp was then digested with KpnI and PstI in order to isolate a PstI/KpnI fragment of 520 bp (fragment B). Fragments A and B were ligated both at once to the vector pBS-SK+ (Stratagene), which had previously been digested with KpnI and SacI, to give the plasmid pRD022 (FIG. 2). Plasmid pRD007 was digested with SalI and XhoI in order to isolate the SalI/XhoI fragment of 730 bp (positions 1876 to 2608 in SEQ ID NO. 1) (positions 6491 to 6980 in the HVT U s  sequence (Zelnik V. et al. J. Gen. Virol. 1993. 74. 2151-2162). This fragment was cloned into the SalI site of vector pBS-SK+ to give the plasmid pRD027 (FIG. 2). 
     A synthetic double-stranded oligonucleotide was obtained by hybridizing the two following oligonucleotides: 
     RD048 (SEQ ID NO. 4) 5&#39; GATCCAGCTGAATTCAGCTA 3&#39; 
     RD049 (SEQ ID NO. 5) 5&#39; AGCTTAAGCTGAATTCAGCTG 3&#39; 
     This oligonucleotide was cloned between the BamHI and HindIII sites of plasmid pRD022 to give the plasmid pRD023 (FIG. 3). The plasmid pCMVβ (Clontech Cat#6177-1) (FIG. 4) was digested with EcoRI and SalI in order to isolate the EcoRI/SalI fragment of 4500 bp which contains the HCMV-IE=lacZ expression cassette (fragment C). Plasmid pRD027 was digested with HindIII and XhoI in order to isolate the HindIII/XhoI fragment of 730 bp (fragment D). Fragments C and D were ligated both at once to plasmid pRD023, which had previously been digested with EcoRI and HindIII, Give the plasmid pRD029 of 8973 bp (FIG. 3). This plasmid contains the HCMV-IE=lacZ expression cassette in the gI site (complete deletion) of the HVT virus. 
     The plasmid pEL004 (=plasmid pGH004 described in French patent application 92.13109), which contains the IBDV VP2 gene in the form of a BamHI/HindIII cassette, was digested with BamHI and XbaI in order to isolate the BamHI/XbaI fragment (truncated VP2 gene) of 1104 bp. This fragment was cloned into vector pBS-SK+ (Stratagene), which had previously been digested with XbaI and BamHI, to give the plasmid pEL022 of 4052 bp (FIG. 5). Vector pBS-SK+ was digested with EcoRV and XbaI and then ligated to itself in order to give pBS-SK* (modified). Plasmid pEL004 was digested with KpnI and HindIII in order to isolate the KpnI/HindIII fragment of 1387 bp, which contains the complete IBDV VP2 gene. This fragment was cloned into vector pBS-SK*, which had previously been digested with KpnI and HindIII, to give the plasmid pEL023 of 4292 bp (FIG. 6). Plasmid pEL022 was digested with BamHI and NotI in order to isolate the BamHI/NotI fragment of 1122 bp (fragment A). Plasmid pEL023 was digested with BamHI and NotI in order to isolate the BamHI/NotI fragment of 333 bp (fragment B). Fragments A and B were ligated both at once to vector pBS-SK+, which had previously been digested with NotI and treated with alkaline phosphatase, to give the plasmid pEL024 of 4369 bp (FIG. 7). Plasmid pEL024 was then digested with NotI in order to isolate the NotI/NotI fragment of 1445 bp. This fragment was cloned in plasmid pRD029, which had previously been digested with NotI and treated with alkaline phosphatase, to give the plasmid pEL025 of 6904 bp (FIG. 8). 
     5.2. Isolation and purification of the recombinant vHVT2 
     Plasmid pEL025 was digested with SalI to linearize it, then extracted with a phenol/chloroform (19:1) mixture, precipitated with absolute ethanol and taken up once again in sterile water. 24-hour primary CEC cells were then transfected with the following mixture: 1 μg of linearized plasmid pEL025+5 μg of HVT viral DNA in 300 μl of OptiMEM medium (Gibco BRL Cat#041-01985H) and 100 μg of LipofectAMINE diluted in 300 μl of medium (final volume of the medium=600 μl). These 600 μl were then diluted in 3 ml (final volume) of medium and plated out on 3.10 6  CEC I. The mixture was left in contact with the cells for 5 hours and then removed and replaced with 5 ml of culture medium. The cells were then cultured at 37° C. for 3 days and, after that, they were pronased, mixed with fresh CEC II (3:1 mixture) and replated out 1 96-well plate. This plate was cultured for 3 days and, after that, the cells were pronased, mixed with fresh CEC II and respread on 2 96-well plates, with one initial well giving 2 sister wells. The 96-well plates were cultured until a cytopathic effect appeared. After 72 hours of culture, one of the two 96-well plates was fixed with 95% acetone for 30 minutes and an indirect immunofluorescence (IIF) reaction was carried out using a monoclonal anti-VP2 antibody to screen for plaques expressing the VP2 protein. The &#34;sister&#34; wells of the wells displaying positive plaques in IIF were pronased, mixed with fresh CEC II, and deposited, in limiting dilution, on 96-well plates. After 3 days of culture, the wells displaying a cytopathic effect were pronased, mixed with CEC II, and replated out on 96-well plates, with one initial well giving 2 sister wells. 3 days later, screening took place once again, using IIF as before, for the plaques expressing the VP2 protein on one of the 2 sister plates. In general, 4 consecutive cycles of isolation (harvesting a well, replating out, checking with IIF, subculturing a sister well, etc.) are sufficient to obtain recombinant viruses all of whose progeny display a specific fluorescence. One viral plaque which gave plaques all of which were positive by IIF using a monoclonal anti-VP2 antibody was designated vHVT2. The genomic DNA of this recombinant virus was characterized at the molecular level by conventional PCR and Southern blot techniques using the appropriate oligonucleotides and DNA probes. This recombinant contains a HCMV-IE/IBDV VP2 cassette in place of the gI gene of the HVT virus. 
     EXAMPLE 6 
     Construction of the Donor Plasmid pEL042 and Isolation of the vHVT4 
     6.1. Construction of the donor plasmid pEL042 
     The BamHI M fragment of 3.3 kbp from the genome of the HVT virus strain FC126 (Igarashi T. et al. Virology. 1989. 70. 1789-1804) was cloned into the BamHI site of the vector pBR322 to give the plasmid pRD002. The sequence of the BamHI M fragment was established in its entirety (3336 bp) (SEQ ID NO. 6 and FIG. 9). This sequence contains an ORF encodes a protein which is homologous to the product of the HSV-1 UL43 gene (positions 1306 to 2511) (end of the stop codon) in the sequence SEQ ID NO. 6, FIG. 9). The protein which is theoretically encoded by this ORF is 401 amino acids (aa) in size. Plasmid pRD002 was digested with SacI and SalI in order to isolate the SacI/SalI fragment of 2620 bp. This fragment was ligated into vector pBS-SK+, which had previously been digested with SacI and XhoI, to give the plasmid pMB010 of 5506 bp (FIG. 10). Plasmid pMB010 was then digested with NcoI and XhoI in order to isolate the NcoI/XhoI fragment of 4650 bp. This fragment was ligated to a double-stranded synthetic oligonucleotide which was obtained by hybridizing the 2 following oligonucleotides: 
     MB014 (SEQ ID NO. 7) 5&#39; TCGAGAATTCAGATCTGATATCAAGCTTGGTACCGTCGAC 3&#39; 
     MB015 (SEQ ID NO. 8) 5&#39; CATGGTCGACGGTACCAAGCTTGATATCAGATCTGAATTC 3&#39; 
     to give the plasmid pMB016 of 4698 bp (FIG. 10). The inserted oligonucleotide contains restriction sites which allow the insertion of an expression cassette between the two flanking arms of the UL43 locus. The 5&#39; flanking arm has a size of 800 bp (position 523 to position 1323 in the sequence of the BamHI M fragment (SEQ ID NO. 6). The 3&#39; arm has a size of 981 bp (positions 2171 to 3152 in SEQ ID NO. 6). The deletion which is thus obtained in the HVT UL43 gene extends from position 1324 to position 2170 (deletion of 847 nucleotides, that is 282 aa out of a total of 401 aa). Plasmid pEL024 (see Example 5) was digested with NotI in order to isolate the NotI/NotI fragment of 1445 bp. This fragment was ligated to plasmid pCMVβ, which had previously been digested with NotI, to give the plasmid pEL026 of 5095 bp (FIG. 11). Plasmid pEL026 was digested with EcoRI, SalI and XmnI in order to isolate the EcoRI/SalI fragment of 2428 bp. This fragment was ligated to vector pBS-SK+, which had previously been digested with EcoRI and SalI, to give the plasmid pEL027 of 5379 bp (FIG. 12). Plasmid pEL027 was digested with EcoRI, SalI and XmnI in order to isolate the EcoRI/SalI fragment of 2428 bp. This fragment was ligated into plasmid pMB016, which had previously been digested with EcoRI and SalI, to give the plasmid pEL042 of 7110 bp (FIG. 13). 
     6.2. Isolation and purification of recombinant vHVT4 
     A cotransfection of CEC II with plasmid pEL042, linearized with KpnI, and HVT viral DNA was carried out as described in Example 5. The conditions for transfection, and for isolating and purifying the recombinant viral plaques which resulted from this cotransfection were those described in Example 5. 
     A viral plaque which gave plaques all of which were positive by IIF using a monoclonal anti-IBDV VP2 antibody was designated vHVT4. The genomic DNA of this recombinant virus was characterized at the molecular level by the conventional techniques of PCR and Southern blot using the appropriate oligonucleotides and DNA probes. 
     EXAMPLE 7 
     Construction of the Donor Plasmid pEL072 and Isolation of vHVT6 
     Plasmid pCMVβ (FIG. 4) was digested with SalI and SmaI in order to isolate the SalI/SmaI fragment of 3679 bp, which fragment contained the lacZ gene as well as the polyadenylation signal of the late gene of the SV40 virus. This fragment was inserted into vector pBS-SK+, which had previously been digested with SalI and EcoRV, to give the plasmid pCD002 of 6625 bp (FIG. 14). This plasmid contains the lacZ reporter gene, but no promoter is situated upstream of this gene. The viral genomic DNA of the MCMV virus was prepared as described in Example 2 and digested with PstI in order to isolate the PstI/PstI fragment of 2285 bp. This fragment was cloned into vector pBS-SK+, which had previously been digested with PstI and treated with alkaline phosphatase, to give the plasmid pCD004. Plasmid pCD004 was digested with HpaI and PstI in order to isolate the HpaI/PstI fragment of 1389 bp, which contains the promoter/enhancer region of the immediate early gene of murine cytomegalovirus (MCMV) (Dorsch-Hasler K. et al. Proc. Natl. Acad. Sci. 1985. 82. 8325-8329, and patent application WO-A-87/03905). This fragment was cloned into plasmid pCD002, which had previously been digested with PstI and SmaI, to give the plasmid pCD009 of 8007 bp (FIG. 15). 
     A double-stranded oligonucleotide was obtained by hybridizing the two following oligonucleotides: 
     MB070 (SEQ ID NO. 9) 5&#39; CGAATTCACTAGTGTGTGTCTGCAGGCGGCCGCGTGTGTGTCGACGGTAC 3&#39; 
     MB071 (SEQ ID NO. 10) 5&#39; CGTCGACACACACGCGGCCGCCTGCAGACACACACTAGTGAATTCGAGCT 3&#39; 
     This double-stranded oligonucleotide was ligated to vector pBS-SK+, which had previously been digested with KpnI and SacI, to give the plasmid pEL067. 
     Plasmid pCD009 was digested with PstI and SpeI in order to isolate the PstI/SpeI fragment of 1396 bp. This fragment was ligated to plasmid pEL067, which had previously been digested with PstI and SpeI, to give the plasmid pEL068 of 4297 bp (FIG. 16). Plasmid pEL024 (see Example 5) was digested with HindIII and NotI in order to isolate the HindIII/NotI fragment of 1390 bp (fragment A). Plasmid pEL027 (see Example 6) was digested with HindIII and SalI in order to isolate the HindIII/SalI fragment of 235 bp (fragment B). Fragments A and B were ligated both at once to plasmid pEL068, which had previously been digested with NotI and SalI, to give the plasmid pEL070 of 5908 bp (FIG. 17). Plasmid pEL070 was digested with EcoRI, SalI and XmnI in order to isolate the EcoRI/SalI fragment of 3035 bp. This fragment was ligated to plasmid pMB016 (see Example 6), which had previously been digested with EcoRI and SalI, to give the plasmid pEL072 of 7702 bp (FIG. 18). This plasmid permits the insertion of the MCMV-IE/IBDV VP2 expression cassette into the UL43 locus of the HVT virus. 
     A cotransfection which was carried out, as described in Example 5, with plasmid pEL072 and genomic DNA of the HVT virus led to the isolation and purification of the vHVT6 recombinant. 
     EXAMPLE 8 
     Construction of the Donor Plasmid pCD012 and Isolation of vHVT7 
     The EcoRI/SalI fragment of 3.9 kbp from the genomic DNA of the MDV virus strain RB1B, which fragment contains the MDV gB gene (sequence published by Ross N. et al. J. Gen. Virol. 1989. 70. 1789-1804), was ligated to the vector pUC13, which had previously been digested with EcoRI and SalI, to give the plasmid pCD007. This plasmid was digested with SacI and XhoI in order to isolate the SacI/XhoI fragment of 2260 bp (central portion of the gB gene=fragment A). A PCR was carried out using the following oligonucleotides: 
     CD001 (SEQ ID NO. 11) 5&#39; GACTGGTACCGCGGCCGCATGCACTTTTTAGGCGGAATTG 3&#39; 
     CD002 (SEQ ID NO. 12) 5&#39; TTCGGGACATTTTCGCGG 3&#39; 
     and the pCD007 template in order to produce a PCR fragment of 222 pb. This fragment was digested with KpnI and XbaI in order to isolate a KpnI/XbaI fragment of 190 bp (5&#39; end of the gB gene=fragment B). Another PCR was carried out using the following oligonucleotides: 
     CD003 (SEQ ID NO. 13) 5&#39; TATATGGCGTTAGTCTCC 3&#39; 
     CD004 (SEQ ID NO. 14) 5&#39; TTGCGAGCTCGCGGCCGCTTATTACACAGCATCATCTTCTG 3&#39; 
     and the pCD007 template in order to produce a PCR fragment of 195 bp. This fragment was digested with SacI and SacII in order to isolate the SacI/SacII fragment of 162 bp (3&#39; end of the gB gene=fragment C). Fragments A, B and C were ligated both at once to vector pBS-SK+, which had previously been digested with KpnI and SacI, to give the plasmid pCD011 of 5485 bp (FIG. 19). Plasmid pCD011 was digested with NotI in order to isolate the NotI/NotI fragment of 2608 bp (entire MDV gB gene=fragment D). Plasmid pEL042 (see Example 6) was digested with NotI and treated with alkaline phosphatase in order to isolate the NotI/NotI fragment of 5706 bp (fragment E). Fragments D and E were then ligated together to give the plasmid pCD012 of 8314 bp (FIG. 20). This plasmid permits insertion of the HCMV-IE/MDV gB cassette into the UL43 locus of the HVT virus. 
     A cotransfection which was carried out, as described in Example 5, using plasmid pCD012 and genomic DNA of the HVT virus led to the isolation and purification of the vHVT7 recombinant. 
     EXAMPLE 9 
     Construction of the Donor Plasmid pEL043 and Isolation of vHVT8 
     Construction of a complementary DNA library of the genome of Newcastle disease virus (NDV), strain Texas, was carried out as described by Taylor J. et al. (J. Virol. 1990. 64. 1441-1450). A pBR322 clone which contained the end of the fusion (F) gene, the whole of the hemagglutinin neuraminidase (HN) gene and the beginning of the polymerase gene was identified and termed pHN01. The sequence of the NDV EN gene contained in this clone is depicted in FIG. 21 (SEQ ID NO. 15). Plasmid pHN01 was digested with SphI and XbaI in order to isolate the SphI/XbaI fragment of 2520 bp. This fragment was ligated with vector pUC19, which had previously been digested with SphI and XbaI, to give the plasmid pHN02 of 5192 bp. Plasmid pHN02 was digested with ClaI and PstI in order to isolate the ClaI/PstI fragment of 700 bp (fragment A). A PCR was carried out using the following oligonucleotides: 
     EL071 (SEQ ID NO. 16) 5&#39; CAGACCAAGCTTCTTAAATCCC 3&#39; 
     EL073 (SEQ ID NO. 17) 5&#39; GTATTCGGGACAATGC 3&#39; 
     and the pHN02 template in order to produce a PCR fragment of 270 bp. This fragment was digested with HindIII and PstI in order to isolate a HindIII/PstI fragment of 220 bp (fragment B). Fragments A and B were ligated both at once to vector pBS-SK+, which had previously been digested with ClaI and HindIII, to give the plasmid pEL028 of 3872 bp (FIG. 22). Plasmid pHN02 was digested with BsphI and ClaI in order to isolate the BsphI/ClaI fragment of 425 bp (fragment C). A PCR was carried out using the following oligonucleotides: 
     EL074 (SEQ ID NO. 18) 5&#39; GTGACATCACTAGCGTCATCC 3&#39; 
     EL075 (SEQ ID NO. 19) 5&#39; CCGCATCATCAGCGGCCGCGATCGGTCATGGACAGT 3&#39; 
     and the pHN02 template in order to produce a PCR fragment of 465 bp. This fragment was digested with BsphI and NotI in order to isolate the BsphI/NotI fragment of 390 bp (fragment D). Fragments C and D were ligated both at once to vector pBS-SK+, which had previously been digested with ClaI and NotI, to give the plasmid pEL029bis of 3727 bp (FIG. 23). Plasmid pEL028 was digested with ClaI and SacII in order to isolate the ClaI/SacII fragment of 960 bp (fragment E). Plasmid pEL029bis was digested with ClaI and NotI in order to isolate the ClaI/NotI fragment of 820 bp (fragment F). Fragments E and F were ligated both at once to vector pBS-SK+, which had previously been digested with NotI and SacII, to give the plasmid pEL030 of 4745 bp (FIG. 24). Plasmid pEL030 was digested with NotI in order to isolate the NotI/NotI fragment of 1780 bp (entire NDV HN gene). This fragment was ligated, in place of the lacZ gene, to plasmid pCMVβ, which had previously been digested with NotI and treated with alkaline phosphatase, to give the plasmid pEL032 of 5471 bp (FIG. 25). Plasmid pEL032 was digested with EcoRI and ClaI in order to isolate the EcoRI/ClaI fragment of 1636 bp (Fragment G). Plasmid pEL032 was digested with ClaI and SalI in order to isolate the ClaI/SalI fragment of 1182 bp (Fragment H). Fragments G and H were ligated both at once to plasmid pMB016 (see Example 6), which had previously been digested with EcoRI and SalI, to give the plasmid pEL043 of 7486 bp (FIG. 26). This plasmid permits insertion of the HCMV-IE/NDV EN expression cassette into the UL43 locus of the HVT virus. 
     A cotransfection which was carried out, as described in Example 5, using plasmid pEL043 and genomic DNA of the HVT virus led to the isolation and purification of the vHVT8 recombinant. 
     EXAMPLE 10 
     Construction of the Donor Plasmid pEL044 and Isolation of vHVT9 
     A clone deriving from the complementary DNA library of the genome of Newcastle disease virus (see Example 9), and containing the whole of the fusion (F) gene, was termed pNDV81. This plasmid has been described previously and the sequence of the NDV F gene which is present in this clone has been published (Taylor J. et al. J. Virol. 1990. 64. 1441-1450). Plasmid pNDV81 was digested with NarI and PstI in order to isolate the NarI/PstI fragment of 1870 bp (fragment A). A PCR was carried out using the following oligonucleotides: 
     EL076 (SEQ ID NO. 20) 5&#39; TGACCCTGTCTGGGATGA 3&#39; 
     EL077 (SEQ ID NO. 21) 5&#39; GGATCCCGGTCGACACATTGCGGCCGCAAGATGGGC 3&#39; 
     and the pNDV81 template in order to produce a fragment of 160 pb. This fragment was digested with PstI and SalI in order to isolate the PstI/SalI fragment of 130 bp (fragment B). Fragments A and B were ligated both at once to vector pBS-SK+, which had previously been digested with ClaI and SalI, to give the plasmid pEL033 of 4846 bp (FIG. 27). Plasmid pEL033 was digested with NotI in order to isolate the NotI/NotI fragment of 1935 bp (entire F gene). This fragment was ligated to plasmid pCMVβ, which had previously been digested with NotI and treated with alkaline phosphatase, to give the plasmid pEL034 of 5624 bp (the NDV F gene has replaced the lacZ gene) (FIG. 28). Plasmid pEL034 was digested with EcoRI and KpnI in order to isolate the EcoRI/KpnI fragment of 866 pb (Fragment C). Plasmid pEL034 was digested with KpnI and SalI in order to isolate the KpnI/SalI fragment of 2114 bp (Fragment D). Fragments C and D were ligated both at once to plasmid pMB016 (see Example 6), which had previously been digested with EcoRI and SalI, to give the plasmid pEL044 of 7639 bp (FIG. 29). This plasmid permits insertion of the HCMV-IE/NDV F expression cassette into the UL43 locus of the HVT virus. A cotransfection which was carried out, as described in Example 5, using plasmid pEL044 and genomic DNA of the HVT virus led to the isolation and purification of the vHVT9 recombinant. 
     EXAMPLE 11 
     Construction of the Donor Plasmid pEL082 and Isolation of vHVT10 
     The sequences situated upstream of the MDV 1.8 kbp RNA gene are described in Bradley G, et al. (J. Virol. 1989. 63. 2534-2542) (FIG. 30 and SEQ ID NO. 22). A PCR amplification was carried out on DNA extracted from lymphocytes which were harvested from chicks infected with the MDV RB1B strain (see Example 1) using the following oligonucleotides: 
     MB047 (SEQ ID NO. 23) 5&#39; GGTCTACTAGTATTGGACTCTGGTGCGAACGC 3&#39; 
     MB048 (SEQ ID NO. 24) 5&#39;GTCCAGAATTCGCGAAGAGAGAAGGAACCTC 3&#39; 
     The PCR fragment of 163 bp thus obtained was digested with EcoRI and SpeI and then ligated to plasmid pCD002 (see Example 7), which had previously been digested with EcoRI and SpeI, to give the plasmid pBS002 of 6774 bp (FIG. 31). Plasmid pBS002 contains the promoter of the MDV 1.8 kb RNA gene clone upstream of the lacZ gene. A PCR was carried out using the oligonucleotides: 
     MB047 (SEQ ID NO. 23) and 
     MB072 (SEQ ID NO. 25) 5 &#39; GTGTCCTGCAGTCGCGAAGAGAGAAGGAACCTC 3&#39; 
     and the pBS002 template. The PCR fragment thus obtained was digested with PstI and SpeI in order to isolate a PstI/SpeI fragment of 200 bp. This fragment was ligated to plasmid pEL067 (see Example 7), which had previously been digested with PstI and SpeI, to give the plasmid pEL069 (FIG. 32). Plasmid pCD007 (see Example 8) was digested with EcoRI and XbaI in order to isolate the EcoRI/XbaI fragment of 2670 bp (fragment A). Plasmid pCD011 (see Example 8) was digested with NotI and XbaI in order to isolate the NotI/XbaI fragment of 180 bp (fragment B). Plasmid pEL069 was digested with NotI and SpeI in order to isolate the NotI/SpeI fragment of 180 bp (fragment C). Fragments A, B and C were ligated both at once to plasmid pEL067 (see Example 7), which had previously been digested with EcoRI and SpeI, to give the plasmid pEL080 of 5939 bp (FIG. 33). Plasmid pEL070 (see Example 7) was digested with KpnI and SpeI in order to isolate the KpnI/SpeI fragment of 1345 bp (fragment D). Plasmid pEL070 was also digested with KpnI and SalI in order to isolate the KpnI/SalI fragment of 1658 bp (fragment E). Fragments D and E were ligated both at once to plasmid pEL080, which had previously been digested with SalI and SpeI, to give the plasmid pEL081 of 8938 bp (FIG. 34). Plasmid pEL081 was digested with EcoRI and SalI in order to isolate the EcoRI/SalI fragment of 6066 bp. This fragment was ligated to plasmid pMB016 (see Example 6), which had previously been digested with EcoRI and SalI, finally to give the plasmid pEL082 of 10732 bp (FIG. 35). This plasmid makes it possible to insert the double VP2/MCMV-IE//1.8 kbp RNA/MDV gB expression cassette into the UL43 locus of the HVT virus. 
     A cotransfection which was carried out, as described in Example 5, using plasmid pEL082 and the genomic DNA of the HVT virus led to the isolation and purification of the vHVT10 recombinant. 
     EXAMPLE 12 
     Construction of the Donor Plasmid pEL096 and Isolation of vHVT22 
     Plasmid pEL080 (see Example 11) was digested with EcoRI and SalI in order to isolate the EcoRI/SalI fragment of 3040 bp (1.8 kbp RNA/MDV gB cassette). This fragment was ligated to plasmid pMB016 (see Example 6), which had previously been digested with EcoRI and SalI, to give the plasmid pEL096 of 7733 bp (FIG. 36). This plasmid makes it possible to insert the 1.8 kbp RNA/MDV gB expression cassette into the UL43 locus of the HVT virus. 
     A cotransfection which was carried out, as described in Example 5, using plasmid pEL096 and the genomic DNA of the HVT virus led to the isolation and purification of the vHVT22 recombinant. 
     EXAMPLE 13 
     Construction of Donor Plasmids for Inserting IBV M and S Expression Cassettes into the UL43 Locus of the HVT Virus 
     Using the same strategy as that which is described above for inserting expression cassettes (genes placed under the control of the HCMV-IE or MCMV-IE promoters or the MCMV-IE//1.8 kbp RNA double promoter) into the UL43 locus, it is possible to produce recombinant HVT viruses which express the membrane (M) or spike (S) proteins of avian infectious bronchitis virus (IBV) at an elevated level. A construct is preferably produced in which the IBV S gene is dependent on the HCMV-IE promoter or the MCMV-IE promoter, or else a construct in which the IBV M and IBV S genes are inserted together with the MCMV-IE/1.8 kbp RNA double promoter in the UL43 locus, the M gene being under the control of the 1.8 kbp RNA promoter and the S gene being under the control of the MCMV-IE promoter. In this configuration, the 1.8 kbp RNA promoter is activated by the enhancer region of the MCMV-IE promoter. 
     EXAMPLE 14 
     Study of the Viremia Induced by the vHVT1, vHVT2 and vHVT4 Recombinants (In Vivo Replication) 
     The viremia which was induced by inoculating the different recombinant viruses was studied in order to evaluate the degree to which the genomic modifications following upon insertion of the expression cassettes brought about an attenuation of replication in vivo. 
     The recombinant viruses to be tested were diluted in Marek vaccine diluent in order to obtain different inoculums for each recombinant. The viral suspensions produced in this way were administered by the intramuscular route to several groups of 1-day-old SPF chicks at the rate of 0.2 ml per chick. Control chicks were given 0.2 ml of Marek vaccine diluent in the same manner. 
     The blood of chicks taken at random from each inoculated group was then withdrawn individually by taking terminal blood samples into anticoagulant (heparin solution of 100 IU/ml) at 7, 11 and 21 days after inoculation. In order to isolate the leucocytes, each withdrawn blood sample was transferred into a tube and centrifuged for 15 minutes at 30 g and at ambient temperature. The plasma and the band of leucocytes (buffy coat) were removed and diluted in sterile PBS in order to obtain a final volume of 10 ml. After centrifuging at 150 g for 15 minutes at ambient temperature, the cell pellet was taken up in 2 ml of 199 medium containing 2% FCS. The viable leucocytes were then counted and their concentration calculated. Determination of the number of infected lymphocytes is carried out as follows: 10 6  or 2.10 6  viable leucocytes, diluted in 2 ml of 199 medium, are added to a 60 mm-diameter Petri dish which was seeded 24 hours previously with from 1.5 to 2.10 6  CEC II/dish. After 2 hours of culture, the medium in each dish is removed and replaced with 5 ml of hypotonic 199 medium containing 1% FCS. The dishes are then incubated at 37° C. for 4 days in a 5% CO 2  incubator. The plaques which have appeared on the lawn are not read until the end of the 4th day after commencing the coculture. 
     RESULTS 
     The viremia induced by the recombinant viruses vHVT1 (RR2 locus), vHVT2 (gI locus) and vHVT4 (UL43 locus) was studied and compared with the viremia induced by the parental HVT virus strain FC126. 
     The results are summarized in Table 1 (individual values obtained for 4-5 chicks per group and per day of withdrawal). The viremia observed for each of the recombinants is indicative of the in vivo replication. 
     
                       TABLE 1______________________________________Viremias induced by the HVT recombinants         Number of viremic chicks/         number of chicks in the groupVaccine   Dose (PFU)               Day 7      Day 11                                Day 21______________________________________vHVT1     10.sup.4  5/5        1/5   0/5vHVT1     10.sup.3  2/5        1/5   0/5vHVT2     10.sup.4  0/5        0/5   0/5vHVT2     10.sup.3  0/5        0/5   0/5vHVT4     10.sup.3  2/4        4/4   3/4HVT FC126 10.sup.4  4/4        4/4   4/4HVT FC126 10.sup.3  4/4        4/4   4/4Controls  --        0/2        0/2   0/2______________________________________ 
    
     CONCLUSIONS 
     Insertion of an expression cassette into the RR2 locus results in a certain attenuation of in vivo replication. Insertion into the gI locus causes a considerable decrease in in vivo replication, since no viremia can be measured even after inoculating 10 4  PFU of recombinant virus/chick. By contrast, insertion into the UL43 locus only brings about weak attenuation of the viremia, making this a good locus for introducing expression cassettes into the genome of the HVT virus. 
     EXAMPLE 15 
     Study of Protection against Gumboro 
     The protection against Gumboro disease which was induced by different recombinant HVT viruses was studied in a chick vaccination/challenge model and compared with that induced by a conventional inactivated vaccine (Gumboriffa, Rhone Merieux). 
     Groups of one-day-old SPF chicks were vaccinated by the intramuscular route with the recombinant viruses or with the inactivated vaccine. 21 days after vaccination, all the chicks were challenged by the ocular route with a dose of 10 2 .5 IOD 50  of IBDV virus strain Faragher. 4 days (trial 1) or 10 days (trial 2) after the challenge, the surviving animals are sacrificed, weighed and then dissected in order to recover the bursa of Fabricius. The bursas are weighed and examined for the presence of lesions caused by Gumboro disease. The final protection is evaluated in accordance with two criteria: 1) the presence or absence of lesions in the bursa. 2) the bursa weight/body weight ratio expressed in %. A non-vaccinated and non-challenged control group, and also a non-vaccinated and challenged control group, enable reference values to be obtained for &#34;protected&#34; chicks and non-protected chicks, respectively. The protected chicks must have, in the absence of macroscopic lesions in the bursa, a bursa weight/body weight ratio of &gt;0.4%. Chicks which have a bursa weight/body weight ratio of ≦0.4% are not protected. 
     The protection results are presented in Tables 2 and 3 below. 
     
                       TABLE 2______________________________________Trial 1: Protection results obtained with vHVT1 Number                 No. of PositiveChick of               Dose  dead/  chicks/                                     Protectiongroup chicks  Vaccine  (PFU) total No.                               total %______________________________________1     12      vHVT1    10.sup.5                        0/12    6/12 50%2     12      vHVT1    10.sup.4                        2/12    8/12 33%3     12      vHVT1    10.sup.3                        1/12   12/12 0%4     12      vHVT1    10.sup.2                        4/12   12/12 0%5     12      challenged                  --    7/12   12/12 0%         controls______________________________________ 
    
     
                       TABLE 3______________________________________Protection results obtained with vHVT2 and vHVT4Number                  No. of PositiveChickof                Dose  dead/  chicks/                                     Protectiongroupchicks  Vaccine   (PFU) total No.                               total %______________________________________1    10      vHVT2     10.sup.4                        0/10   4/10   60%2     9      vHVT2     10.sup.3                        4/9    9/9    0%3    11      vHVT4     10.sup.4                        0/11   0/11  100%4    11      vHVT4     10.sup.3                        0/11   0/11  100%5    11      vHVT4     10.sup.2                        0/11   0/11  100%6    10      parenteral                  10.sup.4                        7/10   10/10  0%        HVT7    20      conventional                  0.3 ml                        0/20   0/20  100%        inactivated8    10      challenged                  --    5/10   10/10  0%        controls______________________________________ 
    
     For both chicks and adults, the routes of administration which are preferably used for the recombinant vaccines according to the invention are the intramuscular route, the subcutaneous route and the intraperitoneal route. The conventional techniques for injecting embryonated eggs are employed for carrying out in ovo vaccination using the recombinant vaccines according to the invention. 
     As is conventionally the case for Marek vaccines, the recombinant vaccines according to the invention preferably include, in addition to the virions, cells infected with these virions and/or debris of infected cells. 
     
         __________________________________________________________________________SEQUENCE LISTING(1) GENERAL INFORMATION:(iii) NUMBER OF SEQUENCES: 27(2) INFORMATION FOR SEQ ID NO:1:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 49 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:TGCTGGTACCGTCGACAAGCTTGGATCCGTGCAGATAACACGTACTGGC49(2) INFORMATION FOR SEQ ID NO:2:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 19 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:CATGTAACTCGCCTTGATC19(2) INFORMATION FOR SEQ ID NO:3:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 2608 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: double(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: Herpesvirus of turkey(B) STRAIN: FC126(xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:GAGCTCTCCTGGATGGTGGGACAGGCGCTACGTCTCAACCAGTTTCATTTCTCGCGACGA60ATTACAGCTGGTTTTTGCAGCGCCGTCCCGAGAATTAGATGGTTTATATACGCGCGTAGT120AGTTGTCAACGGGGACTTTACTACGGCCGATATAATGTTTAATGTTAAAGTGGCATGTGC180CTTTTCAAAGACTGGAATAGAAGATGATACATTATGCAAACCCTTTCATTTCTTTGCCAA240TGCAACATTGCACAATTTAACCATGATTAGATCGGTAACTCTTCGAGCGCACGAAAGCCA300TTTAAAGGAATGGGTGGCACGGAGAGGTGGTAACGTCCCTGCAGTGCTACTTGAGTCTAC360CATGTATCATGCATCCAATCTGCCTAGAAATTTCAGGGATTTCTACATAAAGTCTCCAGA420TGATTATAAGTATAATCACCTAGATGGGCCATCTGTAATGCTCATCACTGACAGACCTAG480TGAAGATTTGGATGGGAGGCTCGTTCACCAAAGTGACATTTTTACTACTACAAGTCCTAT540AAAACAGGTCCGGTATGAAGAGCATCAGTCACATACAAAGCAGTATCCTGTAAACAAAAT600ACAAGCTATAATTTTTTTGATAGGGTTAGGCTCGTTCATTGGAAGCATATTCGTAGTTTT660GGTAGTATGGATTATACGCAGATATTGCAATGGAGCGCGGAGTGGGGGAACGCCCCCCAG720TCCTCGCCGGTATGTGTATACCAGGCTATGATCACGTGTGAAACTTGGGCGGACCTGTAT780CATATGTACACCGTCCCTATTCGTTTATAGCCAGTACGTGTTATCTGCACATAGAGGAAC840ATGTGTCATACTGGGATCGCATGCATGGTATGTGTGACTCTAATATTATTCTGTATCATA900ATAAAAACACAGTGCATGGTATATAGAGGATCGCTGGTAAGCACTACGGTAGACCAATCG960GCTCAGATTGCATTCTTTGGCATCGATACCGTTGTTAATTTATATGGCAAAGTCTTGTTC1020ATGGGAGATCAGTATTTGGAGGAAATATACTCTGGAACGATGGAAATACTCAAATGGAAT1080CAAGCTAACCGCTGCTATTCTATTGCGCATGCAACATATTACGCCGACTGTCCTATAATC1140AGTTCTACGGTATTCAGAGGATGCCGGGACGCCGTTGTTTATACTAGGCCCCACAGCAGA1200ATTCATCCCCAATATCGAAACGGGCTGCTTTTGACTATTATCGAGCCACGGATGGAGGAT1260TCTGGTATCTATTATATACGCACTTCAATAGATGGTTTTAACAAGAGCGATTATGCGAGA1320ACATCTATTTTTGTATGTAATGGGTCGTCTGGATCGTGTTCTAACCCCCGCCAAAAAGTT1380TCAGATGAAATGTGCATCCCCCACGTAAATCGTATTGCATTTGAGCGATATTTAACCCTA1440CATGTTGGACGGTTGCCCTACGGAGACTTGACATTACAGCAGATACGTAAGGACATGACG1500ACCACCGCTCCTACATATCGTACCATTCGCAGAACTACAGTTAATGAGGGTTTGTTGACA1560GCCAAGACATCCCCTGATATCGATTTAAATGCAACAAATTTGCCCCTACCCATTAGTAAC1620TACACAGATTATATGAGTGTTATTTGGAGACGTGTTGCCTTAAGACGAATTTATGCTTAT1680TTGGTGATCGCTATTATAGCATTGTTGATAGTAACAGTCTGCTCCGCACATAAAAGAGGC1740AGTTGTAGTCGTCGACGTAGAATCTACATAGGCAATGAACCTACTACATTGACTTCGATC1800ACTAACGGAAATTTCCAAGAAAAGGAGACCAAGAATGTACCGTCCGACATCTCAGACGCT1860GAGCTTTTGGAGAGACTCGAGAAGAAGATAGAAATGTTACGGACTGAATAATTTCCAAAT1920GGCAGTTAGGTACCCAGGAATGTTGGGATATGTAGATGTATTAGCTATAAGTCCGTATTT1980AAGGGGAGTGGCCCACCAATAATAAACTCTGGTATTTTTGTCTGGGAATTCAGTTGTGCT2040TTAAGGCGACCTGCTGTTTCGATATGCGCGCGTGTCGATTATCCATCCTCATATTATTAT2100TGCAGACGATCTCGGCGAGTATGATACAACATTTAGATTTATTAGAGGGGCAATCTGTTG2160CAGTCGATATTCCAAGATATCCGCCGCTAACAAACGGTACTATTTATACTGAAACATGGA2220CGTGGATTTCAAGTATTTGCAACGATACATCGATGGGTTATATATGTTTGGATCGCGCAA2280CGTGTTTTCAGGATTTGCTTTTGGGGACATCTTGCGTAAGGTATGGTGAAGAAAAGATCT2340TGAGGGTGGATAGATTTGTTGTGAATAGTGGGTCTCTTGACAGGATAGCGTCTTCTCAGT2400TTCATTATATACCGAATGTAATAATAGGCACTGGACGGGGAAAGGAACTTACTATCTTCA2460ATGCTACATCGCAAATCGCTGGTGTATATACGCGATATACCAGGAACGATAGTAGGCCCG2520CTGTAATGGATGTCCTTTTAGTGTGGGTTTCGGTGCATGGGCAAGCTCCAGATCGTACTA2580TGAACATATATATCACCCCCCCGTCGAC2608(2) INFORMATION FOR SEQ ID NO:4:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:GATCCAGCTGAATTCAGCTA20(2) INFORMATION FOR SEQ ID NO:5:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 21 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:AGCTTAAGCTGAATTCAGCTG21(2) INFORMATION FOR SEQ ID NO:6:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 3336 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: double(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: Herpesvirus of turkey(B) STRAIN: FC126(ix) FEATURE:(A) NAME/KEY: CDS(B) LOCATION: 1306..2508(D) OTHER INFORMATION: /function=&#34;unknown&#34;/product=&#34;HVT UL43 (HSV-1 UL43 homolog)&#34;/gene=&#34;UL43&#34;/standard_name=&#34;UL43&#34;(xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:GGATCCGAGCTTCTACTATACAACGCGGACGATAATTTTGTCCACCCCATCGGTGTTCGA60GAAAGGGTTTTTATGATGGCAGGAATAACTGTCGCATGTGACCACACTGCAGGAGAGGCT120CATACACCCGAGGATATGCAAAAGAAATGGAGGATTATATTGGCAGGGGAAAAATTCATG180ACTATATCGGCATCGTTGAAATCGATCGTCAGTTGTGTGAAAAACCCCCTTCTCACGTTT240GGCGCAGATGGGCTCATTGTACAAGGTACTGTCTGCGGACAGCGCATTTTTGTTCCAATC300GACCGTGATTCCTTCAGCGAATATGAATGGCATGGGCCAACTGCGATGTTTCTAGCATTA360ACTGATTCCAGACGCACTCTTTTAGATGCATTCAAATGTGAAAAGAGAAGGGCAATTGAC420GTCTCCTTTACCTTCGCGGGAGAGCCTCCATGTAGGCATTTAATCCAAGCCGTCACATAC480ATGACCGACGGTGGTTCAGTATCGAATACAATCATTAAATATGAGCTCTGGAATGCGTCT540ACAATTTTCCCCCAAAAAACTCCCGATGTTACCTTTTCTCTAAACAAACAACAATTGAAC600AAAATATTGGCCGTCGCTTCAAAACTGCAACACGAAGAACTTGTATTCTCTTTAAAACCT660GAAGGAGGGTTCTACGTAGGAACGGTTTGTACTGTTATAAGTTTCGAAGTAGATGGGACT720GCCATGACTCAGTATCCTTACAACCCTCCAACCTCGGCTACCCTAGCTCTCGTAGTAGCA780TGCAGAAAGAAGAAGGCGAATAAAAACACTATTTTAACGGCCTATGGAAGTGGTAAACCC840TTTTGTGTTGCATTGGAAGATACTAGTGCATTTAGAAATATCGTCAATAAAATCAAGGCG900GGTACGTCGGGAGTTGATCTGGGGTTTTATACAACTTGCGATCCGCCGATGCTATGTATT960CGCCCACACGCATTTGGAAGTCCTACCGCATTCCTGTTTTGTAACACAGACTGTATGACA1020ATATATGAACTGGAAGAAGTAAGCGCCGTTGATGGTGCAATCCGAGCAAAACGCATCAAC1080GAATATTTCCCAACAGTATCGCAGGCTACTTCCAAGAAGAGAAAACAGTCGCCGCCCCCT1140ATCGAAAGAGAAAGGAAAACCACCAGAGCGGATACCCAATAAAATGCCAGACAAACCCGG1200CATCCTGGTTAGAGGGCAGGTGGGCTGGGCCAACCTTCACGGGCGTCCGACAGATCGGTG1260ACACTCATACGTTAACTAAACGCCGGCAGCTTTGCAGAAGAAAATATGCCTTCC1314MetProSerGGAGCCAGCTCGAGTCCTCCACCAGCTTATACATCTGCAGCTCCGCTT1362GlyAlaSerSerSerProProProAlaTyrThrSerAlaAlaProLeu51015GAGACTTATAACAGCTGGCTAAGTGCCTTTTCATGCGCATATCCCCAA1410GluThrTyrAsnSerTrpLeuSerAlaPheSerCysAlaTyrProGln20253035TGCACTGCGGGAAGAGGACATCGACAAAATGGCAAGAAGTGTATACGG1458CysThrAlaGlyArgGlyHisArgGlnAsnGlyLysLysCysIleArg404550TGTATAGTGATCAGTGTATGTTCCTTAGTGTGCATCGCTGCACATTTA1506CysIleValIleSerValCysSerLeuValCysIleAlaAlaHisLeu556065GCTGTTACCGTGTCGGGAGTGGCATTAATTCCGCTTATCGATCAAAAC1554AlaValThrValSerGlyValAlaLeuIleProLeuIleAspGlnAsn707580AGAGCTTACGGAAACTGTACGGTATGTGTAATTGCCGGATTCATCGCT1602ArgAlaTyrGlyAsnCysThrValCysValIleAlaGlyPheIleAla859095ACGTTTGCTGCACGACTTACGATAAGACTTTCGGAAACGCTTATGCTA1650ThrPheAlaAlaArgLeuThrIleArgLeuSerGluThrLeuMetLeu100105110115GTGGGCAAGCCGGCGCAGTTTATATTTGCTATAATCGCTTCCGTTGCG1698ValGlyLysProAlaGlnPheIlePheAlaIleIleAlaSerValAla120125130GAAACACTGATCAATAACGAGGCGCTTGCCATCAGTAATACTACTTAC1746GluThrLeuIleAsnAsnGluAlaLeuAlaIleSerAsnThrThrTyr135140145AAAACTGCATTGCGAATAATCGAAGTAACATCTTTGGCGTGTTTTGTT1794LysThrAlaLeuArgIleIleGluValThrSerLeuAlaCysPheVal150155160ATGCTCGGGGCAATAATTACATCCCACAACTATGTCTGCATTTCAACG1842MetLeuGlyAlaIleIleThrSerHisAsnTyrValCysIleSerThr165170175GCAGGGGACTTGACTTGGAAGGCGGGATTTTTCATGCTTACCACCGGA1890AlaGlyAspLeuThrTrpLysAlaGlyPhePheMetLeuThrThrGly180185190195ACATTACTCGGTATAACAATACCAAACATACACCCAATCCCTCTCGCG1938ThrLeuLeuGlyIleThrIleProAsnIleHisProIleProLeuAla200205210GGGTTTCTTGCAGTCTATACAATATTGGCTATAAATATCGCTAGAGAT1986GlyPheLeuAlaValTyrThrIleLeuAlaIleAsnIleAlaArgAsp215220225GCAAGCGCTACATTATTATCCACTTGCTATTATCGCAATTGCCGCGAG2034AlaSerAlaThrLeuLeuSerThrCysTyrTyrArgAsnCysArgGlu230235240AGGACTATACTTCGCCCTTCTCGTCTCGGACATGGTTACACAATCCCT2082ArgThrIleLeuArgProSerArgLeuGlyHisGlyTyrThrIlePro245250255TCTCCCGGTGCCGATATGCTTTATGAAGAAGACGTATATAGTTTTGAC2130SerProGlyAlaAspMetLeuTyrGluGluAspValTyrSerPheAsp260265270275GCAGCTAAAGGCCATTATTCGTCAATATTTCTATGTTATGCCATGGGG2178AlaAlaLysGlyHisTyrSerSerIlePheLeuCysTyrAlaMetGly280285290CTTACAACACCGCTGATTATTGCGCTCCATAAATATATGGCGGGCATT2226LeuThrThrProLeuIleIleAlaLeuHisLysTyrMetAlaGlyIle295300305AAAAATTCGTCAGATTGGACTGCTACATTACAAGGCATGTACGGGCTT2274LysAsnSerSerAspTrpThrAlaThrLeuGlnGlyMetTyrGlyLeu310315320GTCTTGGGATCGCTATCGTCACTATGTATTCCATCCAGCAACAACGAT2322ValLeuGlySerLeuSerSerLeuCysIleProSerSerAsnAsnAsp325330335GCCCTAATTCGTCCCATTCAAATTTTGATATTGATAATCGGTGCACTG2370AlaLeuIleArgProIleGlnIleLeuIleLeuIleIleGlyAlaLeu340345350355GCCATTGCATTGGCTGGATGTGGTCAAATTATAGGGCCTACATTATTT2418AlaIleAlaLeuAlaGlyCysGlyGlnIleIleGlyProThrLeuPhe360365370GCCGCGAGTTCGGCTGCGATGTCATGTTTTACATGTATCAATATTCGC2466AlaAlaSerSerAlaAlaMetSerCysPheThrCysIleAsnIleArg375380385GCTACTAATAAGGGTGTCAACAAATTGGCAGCAGCAGTGTCG2508AlaThrAsnLysGlyValAsnLysLeuAlaAlaAlaValSer390395400TGAAATCTGTACTGGGCTTCATTATTTCCGGGATGCTTACTTGCGTGCTATTACCACTAT2568CGTGATAGATCGTCGGTCTGCGCATCGCCCATGCTGGCGGAACGCTCTTTCGAACCGTGA2628ATAAAACTTTGTATCTACTAAACAATAACTTTGTGTTTTATTGAGCGGTCGAAAACAATG2688AGGAGCTGCAATTTAAAGCTAACCGCATACGCCGGGCGGGTAAAGACCATTTTATACCAT2748ATTACGCATCTATCGAAACTTGTTCGAGAACCGCAAGTATATGGTTTCCAACATGCGTTC2808TACGCGTACTGCGCTGACGGGATGGGTGGGCATATTTCTAGTTCTGTCTTTACAGCAAAC2868CTCTTGTGCCGGATTGCCCCATAACGTCGATACCCATCATATCCTAACTTTCAACCCTTC2928TCCCATTTCGGCCGATGGCGTTCCTTTGTCAGAGGTGCCCAATTCGCCTACGACCGAATT2988ATCTACAACTGTCGCCACCAAGACAGCTGTACCGACGACTGAAAGCACTAGTTCCTCCGA3048AGCGCACCGCAACTCTTCTCACAAAATACCTGATATAATCTGCGACCGAGAAGAAGTATT3108CGTATTCCTTAACAATACAGGAAGAATTTTGTGTGACCTTATAGTCGACCCCCCTTCAGA3168CGATGAATGGTCCAACTTCGCTCTTGACGTCACGTTCAATCCAATCGAATACCACGCCAA3228CGAAAAGAATGTAGAGGTTGCCCGAGTGGCCGGTCTATACGGAGTACCGGGGTCGGATTA3288TGCATACCCTAGGAAATCGGAATTAATATCCTCCATTCGACGGGATCC3336(2) INFORMATION FOR SEQ ID NO:7:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 401 amino acids(B) TYPE: amino acid(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:MetProSerGlyAlaSerSerSerProProProAlaTyrThrSerAla151015AlaProLeuGluThrTyrAsnSerTrpLeuSerAlaPheSerCysAla202530TyrProGlnCysThrAlaGlyArgGlyHisArgGlnAsnGlyLysLys354045CysIleArgCysIleValIleSerValCysSerLeuValCysIleAla505560AlaHisLeuAlaValThrValSerGlyValAlaLeuIleProLeuIle65707580AspGlnAsnArgAlaTyrGlyAsnCysThrValCysValIleAlaGly859095PheIleAlaThrPheAlaAlaArgLeuThrIleArgLeuSerGluThr100105110LeuMetLeuValGlyLysProAlaGlnPheIlePheAlaIleIleAla115120125SerValAlaGluThrLeuIleAsnAsnGluAlaLeuAlaIleSerAsn130135140ThrThrTyrLysThrAlaLeuArgIleIleGluValThrSerLeuAla145150155160CysPheValMetLeuGlyAlaIleIleThrSerHisAsnTyrValCys165170175IleSerThrAlaGlyAspLeuThrTrpLysAlaGlyPhePheMetLeu180185190ThrThrGlyThrLeuLeuGlyIleThrIleProAsnIleHisProIle195200205ProLeuAlaGlyPheLeuAlaValTyrThrIleLeuAlaIleAsnIle210215220AlaArgAspAlaSerAlaThrLeuLeuSerThrCysTyrTyrArgAsn225230235240CysArgGluArgThrIleLeuArgProSerArgLeuGlyHisGlyTyr245250255ThrIleProSerProGlyAlaAspMetLeuTyrGluGluAspValTyr260265270SerPheAspAlaAlaLysGlyHisTyrSerSerIlePheLeuCysTyr275280285AlaMetGlyLeuThrThrProLeuIleIleAlaLeuHisLysTyrMet290295300AlaGlyIleLysAsnSerSerAspTrpThrAlaThrLeuGlnGlyMet305310315320TyrGlyLeuValLeuGlySerLeuSerSerLeuCysIleProSerSer325330335AsnAsnAspAlaLeuIleArgProIleGlnIleLeuIleLeuIleIle340345350GlyAlaLeuAlaIleAlaLeuAlaGlyCysGlyGlnIleIleGlyPro355360365ThrLeuPheAlaAlaSerSerAlaAlaMetSerCysPheThrCysIle370375380AsnIleArgAlaThrAsnLysGlyValAsnLysLeuAlaAlaAlaVal385390395400Ser(2) INFORMATION FOR SEQ ID NO:8:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 40 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:TCGAGAATTCAGATCTGATATCAAGCTTGGTACCGTCGAC40(2) INFORMATION FOR SEQ ID NO:9:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 40 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:CATGGTCGACGGTACCAAGCTTGATATCAGATCTGAATTC40(2) INFORMATION FOR SEQ ID NO:10:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 50 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:CGAATTCACTAGTGTGTGTCTGCAGGCGGCCGCGTGTGTGTCGACGGTAC50(2) INFORMATION FOR SEQ ID NO:11:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 50 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:CGTCGACACACACGCGGCCGCCTGCAGACACACACTAGTGAATTCGAGCT50(2) INFORMATION FOR SEQ ID NO:12:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 40 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:GACTGGTACCGCGGCCGCATGCACTTTTTAGGCGGAATTG40(2) INFORMATION FOR SEQ ID NO:13:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 18 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:TTCGGGACATTTTCGCGG18(2) INFORMATION FOR SEQ ID NO:14:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 18 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:TATATGGCGTTAGTCTCC18(2) INFORMATION FOR SEQ ID NO:15:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 41 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:TTGCGAGCTCGCGGCCGCTTATTACACAGCATCATCTTCTG41(2) INFORMATION FOR SEQ ID NO:16:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 2521 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: double(D) TOPOLOGY: linear(ii) MOLECULE TYPE: cDNA(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: Newcastle disease virus(B) STRAIN: Texas(ix) FEATURE:(A) NAME/KEY: CDS(B) LOCATION: 303..2015(D) OTHER INFORMATION: /codon_start=303/function=&#34;neuraminidase&#34;/product=&#34;hemagglutinin neuraminidase&#34;/gene=&#34;HN&#34;/standard_name=&#34;hemagglutinin neuraminidase&#34;/label=HN(xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:TGCTACCTGATGTACAAGCAAAAGGCACAACAAAAGACCTTGTTATGGCTTGGGAATAAT60ACCCTTGATCAGATGAGAGCCACTACAAAAATATGAATACAAACGAGAGGCGGAGGTATC120CCCAATAGCAATTTGCGTGTAAATTCTGGCAACCTGTTAATTAGAAGAATTAAGAAAAAA180CCACTGGATGTAAGTGACAAACAAGCAATACACGGGTAGAACGGTCGGAGAAGCCACCCC240TCAATCGGGAATCAGGCCTCACAACGTCCTTTCTACCGCATCATCAATAGCAGACTTCGG300TCATGGACCGTGCAGTTAGCAGAGTTGCGCTAGAGAATGAAGAAAGA347MetAspArgAlaValSerArgValAlaLeuGluAsnGluGluArg151015GAAGCAAAGAATACATGGCGCTTTGTATTCCGGATTGCAATCTTACTT395GluAlaLysAsnThrTrpArgPheValPheArgIleAlaIleLeuLeu202530TTAATAGTAACAACCTTAGCCATCTCTGCAACCGCCCTGGTATATAGC443LeuIleValThrThrLeuAlaIleSerAlaThrAlaLeuValTyrSer354045ATGGAGGCTAGCACGCCTGGCGACCTTGTTGGCATACCGACTATGATC491MetGluAlaSerThrProGlyAspLeuValGlyIleProThrMetIle505560TCTAAGGCAGAAGAAAAGATTACATCTGCACTCAGTTCTAATCAAGAT539SerLysAlaGluGluLysIleThrSerAlaLeuSerSerAsnGlnAsp657075GTAGTAGATAGGATATATAAGCAGGTGGCCCTTGAGTCTCCATTGGCG587ValValAspArgIleTyrLysGlnValAlaLeuGluSerProLeuAla80859095TTGCTAAACACTGAATCTGTAATTATGAATGCAATAACGTCTCTCTCT635LeuLeuAsnThrGluSerValIleMetAsnAlaIleThrSerLeuSer100105110TATCAAATCAATGGAGCTGCAAATAATAGCGGGTGTGGGGCACCTGTT683TyrGlnIleAsnGlyAlaAlaAsnAsnSerGlyCysGlyAlaProVal115120125CATGACCCAGATTATATCGGGGGGATAGGCAAAGAACTTATTGTGGAT731HisAspProAspTyrIleGlyGlyIleGlyLysGluLeuIleValAsp130135140GACGCTAGTGATGTCACATCATTCTATCCCTCTGCGTTCCAAGAACAC779AspAlaSerAspValThrSerPheTyrProSerAlaPheGlnGluHis145150155CTGAACTTTATCCCGGCACCTACTACAGGATCAGGTTGCACTCGGATA827LeuAsnPheIleProAlaProThrThrGlySerGlyCysThrArgIle160165170175CCCTCATTCGACATAAGCGCTACCCACTACTGTTACACTCACAATGTG875ProSerPheAspIleSerAlaThrHisTyrCysTyrThrHisAsnVal180185190ATATTATCTGGTTGCAGAGATCACTCACACTCATATCAGTACTTAGCA923IleLeuSerGlyCysArgAspHisSerHisSerTyrGlnTyrLeuAla195200205CTTGGCGTGCTTCGGACATCTGCAACAGGGAGGGTATTCTTTTCTACT971LeuGlyValLeuArgThrSerAlaThrGlyArgValPhePheSerThr210215220CTGCGTTCCATCAATTTGGATGACAGCCAAAATCGGAAGTCTTGCAGT1019LeuArgSerIleAsnLeuAspAspSerGlnAsnArgLysSerCysSer225230235GTGAGTGCAACTCCCTTAGGTTGTGATATGCTGTGCTCTAAAATCACA1067ValSerAlaThrProLeuGlyCysAspMetLeuCysSerLysIleThr240245250255GAGACTGAGGAAGAGGATTATAGTTCAATTACGCCTACATCGATGGTG1115GluThrGluGluGluAspTyrSerSerIleThrProThrSerMetVal260265270CACGGAAGGTTAGGGTTTGACGGTCAATACCATGAGAAGGACTTAGAC1163HisGlyArgLeuGlyPheAspGlyGlnTyrHisGluLysAspLeuAsp275280285GTCATAACTTTATTTAAGGATTGGGTGGCAAATTACCCAGGAGTGGGG1211ValIleThrLeuPheLysAspTrpValAlaAsnTyrProGlyValGly290295300GGTGGGTCTTTTATTAACAACCGCGTATGGTTCCCAGTCTACGGAGGG1259GlyGlySerPheIleAsnAsnArgValTrpPheProValTyrGlyGly305310315CTAAAACCCAATTCGCCTAGTGACACCGCACAAGAAGGGAGATATGTA1307LeuLysProAsnSerProSerAspThrAlaGlnGluGlyArgTyrVal320325330335ATATACAAGCGCTACAATGACACATGCCCAGATGAACAAGATTACCAG1355IleTyrLysArgTyrAsnAspThrCysProAspGluGlnAspTyrGln340345350ATTCGGATGGCTAAGTCTTCATATAAGCCTGGGCGGTTTGGTGGAAAA1403IleArgMetAlaLysSerSerTyrLysProGlyArgPheGlyGlyLys355360365CGCGTACAGCAGGCCATCTTATCTATCAAGGTGTCAACATCTTTGGGC1451ArgValGlnGlnAlaIleLeuSerIleLysValSerThrSerLeuGly370375380GAGGACCCGGTGCTGACTGTACCGCCTAATACAATCACACTCATGGGG1499GluAspProValLeuThrValProProAsnThrIleThrLeuMetGly385390395GCCGAAGGCAGAGTTCTCACAGTAGGGACATCTCATTTCTTGTACCAG1547AlaGluGlyArgValLeuThrValGlyThrSerHisPheLeuTyrGln400405410415CGAGGGTCTTCATACTTCTCTCCTGCTTTATTATACCCTATGACAGTC1595ArgGlySerSerTyrPheSerProAlaLeuLeuTyrProMetThrVal420425430AACAACAAAACGGCTACTCTTCATAGTCCTTACACATTCAATGCTTTC1643AsnAsnLysThrAlaThrLeuHisSerProTyrThrPheAsnAlaPhe435440445ACTAGGCCAGGTAGTGTCCCTTGTCAGGCATCAGCAAGATGCCCCAAC1691ThrArgProGlySerValProCysGlnAlaSerAlaArgCysProAsn450455460TCATGTGTCACTGGAGTTTATACTGATCCGTATCCCTTAGTCTTCCAT1739SerCysValThrGlyValTyrThrAspProTyrProLeuValPheHis465470475AGGAACCATACCTTGCGGGGGGTATTCGGGACAATGCTTGATGATGAA1787ArgAsnHisThrLeuArgGlyValPheGlyThrMetLeuAspAspGlu480485490495CAAGCAAGACTTAACCCTGTATCTGCAGTATTTGATAACATATCCCGC1835GlnAlaArgLeuAsnProValSerAlaValPheAspAsnIleSerArg500505510AGTCGCATAACCCGGGTAAGTTCAAGCCGTACTAAGGCAGCATACACG1883SerArgIleThrArgValSerSerSerArgThrLysAlaAlaTyrThr515520525ACATCGACATGTTTTAAAGTTGTCAAGACCAATAAAACATATTGCCTC1931ThrSerThrCysPheLysValValLysThrAsnLysThrTyrCysLeu530535540AGCATTGCAGAAATATCCAATACCCTCTTCGGGGAATTCAGGATCGTT1979SerIleAlaGluIleSerAsnThrLeuPheGlyGluPheArgIleVal545550555CCTTTACTAGTTGAGATTCTCAAGGATGATGGGATTTAAGAAGCTT2025ProLeuLeuValGluIleLeuLysAspAspGlyIle560565570GGTCTGGCCAGTTGAGTCAACTGCGAGAGGGTCGGAAAGATGACATTGTGTCACCTTTTT2085TTTGTAATGCCAAGGATCAAACTGGATACCGGCGCGAGCCCGAATCCTATGCTGCCAGTC2145AGCCATAATCAGATAGTACTAATATGATTAGTCTTAATCTTGTCGATAGTAACTTGGTTA2205AGAAAAAATATGAGTGGTAGTGAGATACACAGCTAAACAACTCACGAGAGATAGCACGGG2265TAGGACATGGCGAGCTCCGGTCCCGAAAGGGCAGAGCATCAGATTATCCTACCAGAGTCA2325CATCTGTCCTCACCATTGGTCAAGCACAAACTGCTCTATTACTGGAAATTAACTGGCGTA2385CCGCTTCCTGACGAATGTGACTTCGACCACCTCATTATCAGCCGACAATGGAAGAAAATA2445CTTGAATCGGCCACTCCTGACACTGAGAGGATGATAAAGCTCGGGCGGGCAGTACACCAG2505ACTCTCGACCACCGCC2521(2) INFORMATION FOR SEQ ID NO:17:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 571 amino acids(B) TYPE: amino acid(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:MetAspArgAlaValSerArgValAlaLeuGluAsnGluGluArgGlu151015AlaLysAsnThrTrpArgPheValPheArgIleAlaIleLeuLeuLeu202530IleValThrThrLeuAlaIleSerAlaThrAlaLeuValTyrSerMet354045GluAlaSerThrProGlyAspLeuValGlyIleProThrMetIleSer505560LysAlaGluGluLysIleThrSerAlaLeuSerSerAsnGlnAspVal65707580ValAspArgIleTyrLysGlnValAlaLeuGluSerProLeuAlaLeu859095LeuAsnThrGluSerValIleMetAsnAlaIleThrSerLeuSerTyr100105110GlnIleAsnGlyAlaAlaAsnAsnSerGlyCysGlyAlaProValHis115120125AspProAspTyrIleGlyGlyIleGlyLysGluLeuIleValAspAsp130135140AlaSerAspValThrSerPheTyrProSerAlaPheGlnGluHisLeu145150155160AsnPheIleProAlaProThrThrGlySerGlyCysThrArgIlePro165170175SerPheAspIleSerAlaThrHisTyrCysTyrThrHisAsnValIle180185190LeuSerGlyCysArgAspHisSerHisSerTyrGlnTyrLeuAlaLeu195200205GlyValLeuArgThrSerAlaThrGlyArgValPhePheSerThrLeu210215220ArgSerIleAsnLeuAspAspSerGlnAsnArgLysSerCysSerVal225230235240SerAlaThrProLeuGlyCysAspMetLeuCysSerLysIleThrGlu245250255ThrGluGluGluAspTyrSerSerIleThrProThrSerMetValHis260265270GlyArgLeuGlyPheAspGlyGlnTyrHisGluLysAspLeuAspVal275280285IleThrLeuPheLysAspTrpValAlaAsnTyrProGlyValGlyGly290295300GlySerPheIleAsnAsnArgValTrpPheProValTyrGlyGlyLeu305310315320LysProAsnSerProSerAspThrAlaGlnGluGlyArgTyrValIle325330335TyrLysArgTyrAsnAspThrCysProAspGluGlnAspTyrGlnIle340345350ArgMetAlaLysSerSerTyrLysProGlyArgPheGlyGlyLysArg355360365ValGlnGlnAlaIleLeuSerIleLysValSerThrSerLeuGlyGlu370375380AspProValLeuThrValProProAsnThrIleThrLeuMetGlyAla385390395400GluGlyArgValLeuThrValGlyThrSerHisPheLeuTyrGlnArg405410415GlySerSerTyrPheSerProAlaLeuLeuTyrProMetThrValAsn420425430AsnLysThrAlaThrLeuHisSerProTyrThrPheAsnAlaPheThr435440445ArgProGlySerValProCysGlnAlaSerAlaArgCysProAsnSer450455460CysValThrGlyValTyrThrAspProTyrProLeuValPheHisArg465470475480AsnHisThrLeuArgGlyValPheGlyThrMetLeuAspAspGluGln485490495AlaArgLeuAsnProValSerAlaValPheAspAsnIleSerArgSer500505510ArgIleThrArgValSerSerSerArgThrLysAlaAlaTyrThrThr515520525SerThrCysPheLysValValLysThrAsnLysThrTyrCysLeuSer530535540IleAlaGluIleSerAsnThrLeuPheGlyGluPheArgIleValPro545550555560LeuLeuValGluIleLeuLysAspAspGlyIle565570(2) INFORMATION FOR SEQ ID NO:18:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 22 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:CAGACCAAGCTTCTTAAATCCC22(2) INFORMATION FOR SEQ ID NO:19:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 16 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:GTATTCGGGACAATGC16(2) INFORMATION FOR SEQ ID NO:20:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 21 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:GTGACATCACTAGCGTCATCC21(2) INFORMATION FOR SEQ ID NO:21:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 36 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:CCGCATCATCAGCGGCCGCGATCGGTCATGGACAGT36(2) INFORMATION FOR SEQ ID NO:22:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 18 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:TGACCCTGTCTGGGATGA18(2) INFORMATION FOR SEQ ID NO:23:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 36 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:GGATCCCGGTCGACACATTGCGGCCGCAAGATGGGC36(2) INFORMATION FOR SEQ ID NO:24:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 800 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: double(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(vi) ORIGINAL SOURCE:(A) ORGANISM: Marek&#39;s disease gammaherpesvirus(B) STRAIN: RB1B(xi) SEQUENCE DESCRIPTION: SEQ ID NO:24:GAATTCCATCACCCCCTGCCGATCTTGCACGCGGGGACGAGCAAAGCGTGCGGTGCGGGC60AGAAAGACAAGGATGGCTGTGGGTTGAAAGATGAAAAACAAATCGCGGTTGTGGGTCATG120AGTGGAGGGAGGGTGCCATCTGTGATGCCGAGAGGTCAAACTATGTTATAAAGAAAAACG180ATGGGTGGGAAATATAATAAAGCAACCGAAATGGTACATAAAAACTAAAAATACCTACAC240GGTTACACCACCGATCAGGCGAAGAAGTTCCAAACGATTAACAACCGGGACGAGACGTTG300CCGTTCGATCCAGGTCTCTGCTTTTTTGTATCTCTTATCCTATACCGCCGCCTCCCGTCC360GACGAGAGCAAGTCGCACCGCCACTCGAGGCCACAAGAAATTACGATTCTTATACGGGTG420GGCGTACCGCCTACTCGAACTATCACGTGATGTGTATGCAAATGAGCAGTGCGAACGCGT480CAGCGTTCGCACTGCGAACCAATAATATATTATATTATATTATATTATTGGACTCTGGTG540CGAACGCCGAGGTGAGCCAATCGGATATGGCGATATGTTATCACGTGACATGTACCGCCC600CAAATTCGCACTTGAGTGTTGGGGGTACATGTGGGGGCGGCTCGGCTCTTGTGTATAAAA660GAGCGGCGGTTGCGAGGTTCCTTCTCTCTTCGCGATGCTCTCTCAGAATGGCACGGCCGA720TCCCCCATATATTTCCTGAAGGAACGCATAGCTAGGCGACGAACGAGCTGAATTTCTCCC780TTCATCAAATAAGTAATAAA800(2) INFORMATION FOR SEQ ID NO:25:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 32 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:25:GGTCTACTAGTATTGGACTCTGGTGCGAACGC32(2) INFORMATION FOR SEQ ID NO:26:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 31 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:26:GTCCAGAATTCGCGAAGAGAGAAGGAACCTC31(2) INFORMATION FOR SEQ ID NO:27:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 33 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: NO(iv) ANTI-SENSE: NO(xi) SEQUENCE DESCRIPTION: SEQ ID NO:27:GTGTCCTGCAGTCGCGAAGAGAGAAGGAACCTC33__________________________________________________________________________