Human immunodeficiency virus-2 infection in baboons is an animal model for human immunodeficiency virus pathogenesis in humans

Objective. - To assess disease progression in baboons (Papio cynocephalus) that were infected with two human immunodeficiency virus-2 (HIV-2) isolates. Methods. - Eight baboons were inoculated intravenously with either HIV-2(UC2) or HIV-2(UC14) and were followed for a 2- to 7-year period of observation. Results. - Six of 8 baboons showed lymphadenopathy and other signs of HIV-related disease, 3 of 8 baboons had an acute phase CD4⁺ T-cell decline, and 2 of 5 baboons infected with the HIV-2(UC2) isolate progressed to an acquired immunodeficiency syndrome-like disease. Human immunodeficiency virus-2-specific pathology in lymphatic tissues included follicular lysis, vascular proliferation, and lymphoid depletion. Both neutralizing antibodies and a CD8⁺ T-cell antiviral response were associated with resistance to disease. Conclusions. - Disease progression and the development of acquired immunodeficiency syndrome in HIV-2-infected baboons have similarities to human HIV infections.