African gene increases odds of HIV infection

July 17th, 2008 - 1:47 pm ICT by IANS  

Washington, July 17 (IANS) A gene variant found only in people of African ancestry increases the chances of becoming infected with HIV-1 by 40 percent, according to a long-term study. Interestingly, however, after infection, the same variant seemed to protect against progression of the disease, allowing those who carry it to live about two years longer.

“It’s well-known that individuals vary in their susceptibility to HIV and that after infection occurs, the disease progresses at variable rates,” said Sunil Ahuja of the University of Texas Health Science Centre.

“The mystery of variable infection and progression was originally thought to be mainly the result of viral characteristics, but in recent years it has become evident that there is a strong host genetic component.”

The new discovery is one of few genetic risk factors for HIV found only in people of African descent, the researchers added. If the new findings can be extrapolated to Africa, where about 90 percent of all people carry the variant, it may be responsible for 11 percent of the HIV burden there, they estimate.

The gene in question encodes a protein found mainly at the surface of red blood cells, which is called Duffy Antigen Receptor for Chemokines (DARC).

The DARC variant found commonly in people of African ancestry leaves them without this particular red blood cell receptor. That so-called “DARC-negative” condition has been well studied because it also confers protection against infection by a malaria parasite known as Plasmodium vivax.

“The big message of this paper is that something that protected people against malaria in the past is now leaving them more susceptible to HIV,” said Robin Weiss of University College London.

The findings have been published in the latest issue of the journal Cell Host & Microbe.

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