Abstract

In asymptomatic human immunodeficiency virus (HIV) infection in humans, disturbed T cell functions such as anergy and programmed cell death, thought to result from inappropriate signal-ing by antigen-presenting cells due to HIV infection, precede increase in virus load, decline in CD4 + T cell numbers, and subsequent disease progression. Here, in 3 long-term HIV-I-infected asymptomatic chimpanzees, antigen-presenting cell function was intact and T cells had normal proliferative capacity with no evidence of HIV-I-associated programmed cell death. Polymerase chain reaction analysis demonstrated low frequencies of cells harboring proviral DNA. Primary virus isolation from the infected animals demonstrated the absence of monocytotropic HIV-I variants, in concordance with complete insusceptibility of chimpanzee monocytes for HIV-I infection. Possibly, because of the incapacity of HIV-l to infect monocytes, systemic immune dysfunction will not occur, contributing to controlled viral replication and maintenance of the asymptomatic state in HIV-infected chimpanzees. In humans, the course of human immunodeficiency virus (HIV) infection is characterized by the early loss of immune function, when CD4+ T cell counts are still within normal