Natural variation of equine infectious anemia virus Gag protein cytotoxic T lymphocyte epitopes.
Two defined cytotoxic T lymphocyte (CTL) epitopes from equine infectious anemia virus (EIAV)-infected horses, equine leukocyte alloantigen (ELA)-A5.1-restricted epitope 18a, and ELA-A9-restricted epitope 28b-1 were evaluated for conservation among three wild-type EIAV strains. Epitope 18a variation occurred in all three wild-type EIAV strains, while epitope 28b-1 varied in one strain. Further, 12% amino acid changes occurred in the Gag proteins of a recently isolated wild-type strain, documenting a much greater Gag protein variation than previously reported. Evaluation of epitope 18a among two virus isolates from sequential disease episodes in a single horse, H513 (ELA-A5.1/A8), demonstrated that no variation that affected CTL recognition occurred. H513 PBMC had CTLm to epitope 18a before the occurrence of disease episodes caused by viruses expressing epitope 18a; however, the frequencies were low (5-15/10(6) PBMC). Later in infection there was an absence of disease episodes associated with an increase in CTLm frequency to EIAV(WSU5)-infected targets, but not epitope 18a-pulsed targets. Therefore, if CTLm to EIAV epitopes were involved in maintaining the carrier state in H513, they recognized epitopes other than 18a.
Zhang
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W
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, USA.
Auyong
D B
DB
Oaks
J L
JL
McGuire
T C
TC
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D000940:Antigenic Variation; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D004859:Equine Infectious Anemia / Q000276:immunology*; D015683:Gene Products, gag / Q000235:genetics / Q000276:immunology*; D006736:Horses; D004860:Infectious Anemia Virus, Equine / Q000276:immunology*; D008969:Molecular Sequence Data; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000956:Antigens, Viral; D000939:Epitopes; D015683:Gene Products, gag