Stages in the progression of HIV infection in chimpanzees.

Circulating HIV antigens and HIV specific antibodies in sera of experimentally infected chimpanzees were monitored by ELISA immunoassay, Western blot, and radioimmunoprecipitation procedures. Three of three chimpanzees given plasma from patients with AIDS or ARC tested positive for HIV antigens beginning six to ten weeks after transfusion. Antigen production rose sharply but was of short duration. Despite their proven infectivity and the presence of anti-HIV antibody, all donors to these chimpanzees tested negative for the HIV antigen. Of the three animals that developed HIV antigen one animal did not produce any HIV antibodies or evidence of disease. A second produced antibodies to only the p24 and p18 antigens and remained clinically well. The third produced antibodies beginning with anti-p24, to all the major HIV proteins except gp120, and then developed marked lymphadenopathy which persisted for 32 weeks. Antibody persistence after the disappearance of clinical disease was variable and was greatest for gp41 and least for p24. These data may be of value in the interpretation of human serological testing for HIV and in further studies of the sequence of events leading to the pathological effects of HIV infection. A significant value of the chimpanzee model is the capacity of this animal to respond in a variety of ways to HIV infection, suggesting the existence of successive or alternate states of early HIV infection, and may have implications in the design of early interventions.