Retroviral etiology of the acquired immune deficiency syndrome (AIDS).

The acquired immune deficiency syndrome (AIDS) is characterized by severe immunological defects resulting in opportunistic infections and malignancies. A novel human retrovirus, known under the terms of LAV, HTLV-III, ARV or as a human immunodeficiency virus (HIV), has been defined as the infectious agent responsible for the induction of the immunologic disorders in AIDS. However, two recent lines of evidence, reviewed in this article, complicate the etiological picture of AIDS: the HIV family appears to consist of a great number of diverse, and perhaps diversifying in vivo, members that exhibit different molecular and biological properties; the human retrovirus family may contain yet another distinct class of member viruses that resemble HIV morphologically and structurally but may differ in their pathogenicity. Our understanding of the retroviral etiology of AIDS may be far from complete.