RESUMO
Sheep infected with maedi visna virus were tested for immune reactivity to recombinant HSP65 and tuberculin PPD from mycobacteria. The results showed that both naturally and experimentally infected animals had elevated IgM but not IgG or IgA antibodies to HSP65 from Mycobacterium leprae or M. bovis. In experimentally infected animals, the elevated IgM antibodies appeared in blood from about 3 to 4 weeks postinfection. Increased T cell proliferative responses to HSP65 and PPD were also found in both naturally and experimentally infected sheep. The T cell responses to HSP65 were substantially inhibited by antibodies to ovine major histocompatibility complex class II molecules, indicating that the responses were class II restricted. Increased expression of a putative HSP65 molecule was observed in synovial membranes from sheep infected with maedi visna virus and goats infected with the related, caprine arthritis encephalitis virus. The results thus show that lentivirus infection induces T and B cell anti-HSP65 immune responses and suggest that synovial inflammation may be due, at least in part, to T and B cell recognition of HSP65-like molecules expressed in joints.