COMPARISON OF ANTI-HIV-1 ADCC REACTIVITIES IN INFECTED HUMANS AND CHIMPANZEES

Despite its shortcomings as a disease model, the chimpanzee is still t he most relevant animal model for human immunodeficiency virus type 1 (HIV-1) infection. Previous studies have revealed qualitative differen ces between human and chimpanzee anti-HIV-1 responses. In this study, the development of specific anti-HIV-1 antibody-dependent cellular cyt otoxic (ADCC) reactivities was evaluated in chronically infected chimp anzees and compared to the human response, because anti-HIV-1 ADCC rep resents a major component of anti-envelope cytolytic response found in infected patients. Ten HIV-1-infected chimpanzees up to 5 years after the infection were investigated. Anti-HIV-1 ADCC-directing antibodies were detectable in only three of 10 infected chimpanzees, and in thes e animals, activity was apparent only several months after the HIV inf ection. In some of the infected animals, ADCC reactivity against infec ted cells preceded reactivity against gp120-coated targets. When anti- gp120 ADCC-directing antibodies were apparent, they exhibited the same broad reactivity described in humans against different HIV isolates. The pattern of ADCC reactivities in infected chimpanzees is completely different from the well-characterized anti-gp120 cytotoxic reactiviti es present in HIV-1-infected patients. It is a relatively rare and lat e-occurring event that may have an important bearing on the lack of vi rus-induced pathogenesis in the chimpanzee model.