The natural history of HIV infection: implications for the assessment of antiretroviral therapy.

Although AIDS is a complex clinical disease with diverse manifestations, infection with human immunodeficiency virus (HIV) per se is almost entirely subclinical. The evaluation of antiretroviral agents is difficult because of the lack of a direct clinical relationship between the replication of HIV and the subsequent development of nonviral opportunistic infection. Thus surrogate markers, especially the results obtained in laboratory assays of the inhibition of replicating virus in vivo, have emerged as important factors in the evaluation of a drug's in vivo antiviral efficacy.