Mucosally transmitted feline immunodeficiency virus induces a CD8+ antiviral response that correlates with reduction of cell-associated virus

Intravaginal inoculation of cats with feline immunodeficiency virus (FIV) results in acute systemic infection accompanied by a strong CD8(+) immune response that inhibits viral replication, CD8(+) anti-FIV activity, revealed by increased FIV replication in peripheral blood mononuclear cells (PBMC) depleted of CD8(+) lymphocytes, was detected by 6 weeks after inoculation and correlated with reduced PBMC-associated virus at 12, 16, and 32 weeks after inoculation, Some cats with strong CD8(+) anti-FIV activity during acute infection did not seroconvert and yielded no evidence of FIV infection at later times, These data suggest that CD8(+) immunity may play a major role in eliminating virus during primary transmucosal FIV infection and may down-regulate viral replication during asymptomatic infection.