Baboons as an animal model for human immunodeficiency virus pathogenesis and vaccine development.

Baboons (Papio cynocephalus) provide a valuable animal model for the study of human immunodeficiency virus (HIV) pathogenesis because HIV-2 infection of baboons causes a chronic viral disease that progresses over several years before clinical signs of acquired immunodeficiency syndrome (AIDS) appear. Since HIV-2-infected baboons develop a chronic viral infection, insights into the immuno-biology of viral latency, clinical stages of disease, virus infection of lymphatic tissue and HIV transmission can be gained using this animal model. The development of an AIDS-like disease in baboons is viral isolate and baboon subspecies dependent. Thus, viral virulence factors and host resistance can be studied as well as the mechanisms of innate and acquired immunity. The control of virus infection is dependent upon cytotoxic and non-cytotoxic antiviral activity of CD8+ T cells. In this regard, some of the HIV-2-infected baboons develop potent antiviral cellular immune responses that have a similar magnitude to that found in HIV-1-infected long-term survivors (or non-progressors). In our laboratory, baboons have been used to study DNA vaccine strategies using new cationic liposome formulations and granulocyte macrophage-colony stimulating factor and B7-2 as genetic adjuvants. The results demonstrate the value of using baboons as an animal model of AIDS pathogenesis and vaccine development.