Development of AIDS in a chimpanzee infected with human immunodeficiency virus type 1.

The condition of a chimpanzee (C499) infected with three different isolates of human immunodeficiency virus type 1 (HIV-1) for over 10 years progressed to AIDS. Disease development in this animal was characterized by (i) a decline in CD4+ cells over the last 3 years; (ii) an increase in viral loads in plasma; (iii) the presence of a virus, termed HIV-1JC, which is cytopathic for chimpanzee peripheral blood mononuclear cells; and (iv) the presence of an opportunistic infection and blood dyscrasias. Genetic analysis of the V1-V2 region of the envelope gene of HIV-1JC showed that the virus present in C499 was significantly divergent from all inoculating viruses (> or = 16% divergent at the amino acid level) and was suggestive of a large quasispecies. Blood from C499 transfused into an uninfected chimpanzee (C455) induced a rapid and sustained CD4+-cell decline in the latter animal, concomitant with high plasma viral loads. These results show that HIV-1 can induce AIDS in chimpanzees and suggest that long-term passage of HIV-1 in chimpanzees can result in the development of a more pathogenic virus.