Why Does Immunodefiency Viruses Lead to AIDS in Humans But Not Other Primates?
After concluding that AIDS was caused by the Human Immunodeficiency Virus, studies were done in order to find the source of HIV which led to the discovery that chimpanzees and sooty mangabeys contract the Simian Immunodeficiency Virus (SIV). Though these primates are the natural hosts for the AIDS virus, they remain shockingly healthy unlike humans who contract the virus inevitable succumb to sickness. To understand how these primary hosts have evolved to resist the development of immunodeficiency disease would bring a breakthrough in this field of study but remains unsolved. What is known is that the immune systems of sooty mangabeys are triggered to a considerably lower amount compared to the systems of rhesus macaques, a monkey that like humans develop AIDS due to SIV infection.
This discovery by a team of scientists from Yerkes National Primate Research center and the Emory Vaccine Center may explain why SIV and HIV infections develop to AIDS in some species of primates but not others. The team’s senior author, Mark Feinberg, MD, PhD, states that "during both HIV infection in humans and SIV infection in macaques, the host immune system becomes highly activated, experiences increased destruction and decreased production of key immune effector cells and progressively fails as a result. In contrast, natural hosts for SIV infection, like sooty mangabeys, do not exhibit this excessive immune activation and do not develop AIDS despite high levels of ongoing SIV replication. The reasons for the significant differences in signaling lie in a specific type of dendritic cells which are part of the immune system that play an important in alerting the body of invading viruses or bacteria. The team of scientists found that AIDS-resistant primates produce much less signals to dendritic cells. In comparison, HIV and SIV readily activate dendritic cells in primates susceptible to AIDS which may lead to significant damage to the immune system. This response is now thought to be a major driving force in the development of AIDS.
By understanding how the AIDS-resistant primates have evolved to resist the disease will provide insights on new treatment strategies and foresights to the evolutionary path of humans in response to HIV especially where infection is most severe.
http://www.sciencedaily.com/releases/2008/09/080916143900.htm
This discovery by a team of scientists from Yerkes National Primate Research center and the Emory Vaccine Center may explain why SIV and HIV infections develop to AIDS in some species of primates but not others. The team’s senior author, Mark Feinberg, MD, PhD, states that "during both HIV infection in humans and SIV infection in macaques, the host immune system becomes highly activated, experiences increased destruction and decreased production of key immune effector cells and progressively fails as a result. In contrast, natural hosts for SIV infection, like sooty mangabeys, do not exhibit this excessive immune activation and do not develop AIDS despite high levels of ongoing SIV replication. The reasons for the significant differences in signaling lie in a specific type of dendritic cells which are part of the immune system that play an important in alerting the body of invading viruses or bacteria. The team of scientists found that AIDS-resistant primates produce much less signals to dendritic cells. In comparison, HIV and SIV readily activate dendritic cells in primates susceptible to AIDS which may lead to significant damage to the immune system. This response is now thought to be a major driving force in the development of AIDS.
By understanding how the AIDS-resistant primates have evolved to resist the disease will provide insights on new treatment strategies and foresights to the evolutionary path of humans in response to HIV especially where infection is most severe.
http://www.sciencedaily.com/releases/2008/09/080916143900.htm
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