Infection with the human immunodeficiency virus type 2.

PURPOSE: To review the clinical, epidemiologic, and biological features of infection with the human immunodeficiency virus type 2 (HIV-2). DATA IDENTIFICATION: Studies published since 1981 identified from MEDLINE searches, articles accumulated by the author, bibliographies of identified articles, and discussions with other investigators. STUDY SELECTION: Information for review was taken from the author's own studies, data from other investigators that have been submitted for publication, and from 131 of the more than 200 articles examined. DATA EXTRACTION: Pertinent studies were selected and the data synthesized into a review format. RESULTS OF DATA SYNTHESIS: Infection with HIV-2 is prevalent in West Africa and is increasingly being identified elsewhere. The human immunodeficiency virus type 2 is spread through sexual contact and via contaminated blood but, unlike HIV-1, perinatal transmission is limited. Human immunodeficiency virus type 2 is genetically much more closely related to the simian immunodeficiency virus (SIV) than to HIV-1; biological and demographic data suggest that HIV-2 may have originally been transmitted from monkeys to man. Although HIV-2 causes the acquired immunodeficiency syndrome (AIDS), the asymptomatic incubation period after infection with HIV-2 appears to be substantially longer than that following HIV-1 infection. Consistent with these clinical observations, genetic regulation of HIV-2 differs from that of HIV-1. Therapeutic studies of patients infected with HIV-2 are lacking. CONCLUSIONS: The human immunodeficiency virus type 2 is prevalent in West Africa and is now recognized on several other continents, including North America. Its epidemiology, biology, and clinical course differ from HIV-1. Therapeutic studies are needed.