title: Novel CD8(+) cytotoxic T cell epitopes in bovine leukemia virus with cattle.
abstract: Bovine leukemia virus (BLV) is associated with enzootic bovine leukosis and is closely related to human T cell leukemia virus (HTLV). The cytotoxic T lymphocyte (CTL) plays a key role in suppressing the progression of disease caused by BLV. T and B cell epitopes in BLV have been studied, but CD8(+) CTL epitopes remain poorly understood. We used a library of 115 synthetic peptides covering the entirety of the Env proteins (gp51 and gp30), the Gag proteins (p15, p24, and p12), and the Tax protein of BLV to identify 11 novel CD8(+) T cell epitopes (gp51N5, gp51N11, gp51N12, gp30N5, gp30N6, gp30N8, gp30N16, tax16, tax18, tax19, and tax20) in four calves experimentally infected with BLV. The number of CD8(+) T cell epitopes that could be identified in each calf correlated with the BLV proviral load. Interestingly, among the 11 epitopes identified, only gp51N11 was capable of inducing CD8(+) T cell-mediated cytotoxicity in all four calves, but it is not a suitable vaccine target because it shows a high degree of polymorphism according to the Wu-Kabat variability index. By contrast, no CTL epitopes were identified from the Gag structural protein. In addition, several epitopes were obtained from gp30 and Tax, indicating that cellular immunity against BLV is strongly targeted to these proteins. CD8(+) CTL epitopes from gp30 and Tax were less polymorphic than epitopes from. Indeed, peptides tax16, tax18, tax19, and tax20 include a leucine-rich activation domain that encompasses a transcriptional activation domain, and the gp30N16 peptide contains a proline-rich region that interacts with a protein tyrosine phosphatase SHP1 to regulate B cell activation. Moreover, at least one CD8(+) CTL epitope derived from gp30 was identified in each of the four calves. These results indicate that BLV gp30 may be the best candidate for the development of a BLV vaccine.
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Wako, Saitama 351-0198, Japan; Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan.
authors.forename: Lanlan
authors.initials: L
authors.lastname: Bai
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Wako, Saitama 351-0198, Japan.
authors.forename: Shin-Nosuke
authors.initials: SN
authors.lastname: Takeshima
authors.affiliation: Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Isogai
authors.affiliation: Animal Research Center, Hokkaido Research Organization, Shintoku, Hokkaido 081-0038, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Kohara
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Wako, Saitama 351-0198, Japan. Electronic address: aida@riken.jp.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Aida
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002417:Cattle; D003601:Cytotoxicity Tests, Immunologic; D016583:Enzootic Bovine Leukosis / Q000276:immunology; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte / Q000032:analysis*; D015686:Gene Products, env / Q000276:immunology; D015683:Gene Products, gag / Q000276:immunology; D016356:Gene Products, tax / Q000276:immunology; D001909:Leukemia Virus, Bovine / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D015686:Gene Products, env; D015683:Gene Products, gag; D016356:Gene Products, tax
keywords: Bovine MHC class I; Bovine leukemia virus; CD8(+) CTL epitope mapping; CD8(+) T cell proliferation; Cytotoxicity; Experimentally infected calves