Protection of sheep against bovine leukemia virus (BLV) infection by vaccination with recombinant vaccinia viruses expressing BLV envelope glycoproteins: correlation of protection with CD4 T-cell response to gp51 peptide 51-70.
We have previously constructed vaccinia virus (VV) recombinants containing a complete or truncated envelope (env) gene of bovine leukemia virus (BLV). Only recombinants carrying the complete env gene (VV-BLV2 and VV-BLV3) expressed env glycoprotein on the surface of virus-infected cells and produced an antibody response in rabbits. In the present study, these VV recombinants were used to immunize sheep prior to challenge with BLV-infected peripheral blood mononuclear cells. Both humoral and cell-mediated immunity were monitored in infected animals. Sheep inoculated with recombinants containing the complete env gene showed a CD4 response to a defined epitope of gp51, but this response was absent 4 months postchallenge. Anti-gp51 antibodies appeared in animals inoculated with complete env 2 weeks after challenge, reached a peak at 4 weeks, and subsequently declined over 16 months. No CD4 response was recorded in animals inoculated with recombinants containing truncated env gene (VV-BLV1). BLV-infected control animals and those animals receiving VV-BLV1 were slower to develop antibodies postchallenge, and the titers of anti-gp51 antibodies continued to increase over 16 months. Proviral DNA was detected by the polymerase chain reaction in the four groups at 6 weeks after challenge. However, it could not be detected 4 months postinfection in the VV groups inoculated with complete env. Provirus was present in the VV-BLV1 and control groups over the 16-month trial period. These results demonstrate that vaccination with VV recombinants containing the complete env gene of BLV protects sheep against infection and that protection correlated with a CD4 T-cell response to a defined epitope.
Gatei
M H
MH
Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, Bancroft Centre, Brisbane.
Naif
H M
HM
Kumar
S
S
Boyle
D B
DB
Daniel
R C
RC
Good
M F
MF
Lavin
M F
MF
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016827:CD8 Antigens / Q000276:immunology; D000939:Epitopes; D015752:Genes, env; D015751:Genes, pol; D007111:Immunity, Cellular; D001909:Leukemia Virus, Bovine / Q000276:immunology*; D007942:Leukemia, Experimental / Q000517:prevention & control*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010455:Peptides / Q000276:immunology; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics; D012191:Retroviridae Proteins / Q000276:immunology; D015682:Retroviridae Proteins, Oncogenic / Q000276:immunology*; D012756:Sheep; D012757:Sheep Diseases / Q000517:prevention & control*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013997:Time Factors; D014611:Vaccination; D014614:Vaccines, Synthetic / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000276:immunology*; D014765:Viral Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D016827:CD8 Antigens; D000939:Epitopes; D009838:Oligodeoxyribonucleotides; D010455:Peptides; D012191:Retroviridae Proteins; D015682:Retroviridae Proteins, Oncogenic; D014614:Vaccines, Synthetic; D014759:Viral Envelope Proteins; D014765:Viral Vaccines