Pathogenicity of SIV in Non-human Primates
In most non-human primate species, natural SIV infection does not cause a fatal disease (but see below). Comparison of the gene sequence of SIV with HIV should therefore give us information about the factors necessary to cause disease in humans. The factors that determine the virulence of HIV as compared to most SIVs are only now being elucidated. Non-human SIVs contain a nef gene that down-regulates CD3, CD4, and MHC class I expression; most non-human SIVs therefore do not induce immunodeficiency; the HIV-1 nef gene however has lost its ability to down-regulate CD3, which results in the immune activation and apoptosis that is characteristic of chronic HIV infection.
In addition, a long term survey of chimpanzees naturally infected with SIVcpz in Gombe, Tanzania, found that, contrary to the previous paradigm, chimpanzees with SIVcpz infection do experience an increased mortality, and also suffer from a Human AIDS-like illness. SIV pathogenicity in wild animals could exist in other chimpanzee subspecies and other primate species as well, and stay unrecognized by lack of relevant long term studies.
Read more about this topic: Origin Of AIDS
Famous quotes containing the word non-human:
“Almost like a god looking at her terribly out of the everlasting dark, she had felt the eyes of that horse; great glowing, fearsome eyes, arched with a question, and containing a white blade of light like a threat. What was his non-human question, and his uncanny threat? She didn’t know. He was some splendid demon, and she must worship him.”
—D.H. (David Herbert)