In the past, physicians who treated AIDS patients understood that this deadly disease was one of immune deficiency. Their patients were immunosuppressed, subject to opportunistic infections, and had odd cancers. Today, because of continuing research on the human and primate immune systems and their responses to retroviruses, AIDS researchers realize that the immunosuppression associated with AIDS is a result of chronic immune hyperactivation. Evidence for this comes from research on a primate called sooty mangabeys, which lives in equatorial Africa.
Sooty mangabeys normally contract simian immunodeficiency virus (SIV) through sexual contact. Despite evidence that SIV has direct toxic effects on CD4+ T cells, the monkey's immune system remains intact, as lost cells are replaced with new ones. This finding, published by Mark Feinberg and colleagues at Emory University School of Medicine,1 may be the clincher in a developing hypothesis: Virus-mediated, direct T-cell killing is not sufficient to cause AIDS; rather, ...
