Battling malaria for millennia helped Africans build barriers against the parasite that causes it, but that defense has proven to be a double-edged sword for HIV infection.
A genetic variation that prevents a protein called the Duffy antigen from being made in red blood cells defends against malaria. But that defense mechanism increases an individual’s chance of contracting HIV by about 40 percent, an international group of researchers reports in the July 17 Cell Host & Microbe. The genetic variant could account for 2 million to 3 million cases of HIV in Africa, where about 95 percent of the population carries the variant. Once infected, though, people who carry the genetic variant are able to survive longer with the disease.
Compared with people of European heritage, people of African descent tend to do slightly better when infected with HIV, says Vicente Planelles, a molecular virologist at the University of Utah School of Medicine in Salt Lake City. When infected with HIV, people of African heritage don’t progress as quickly to AIDS and tend to live slightly longer.
“The slight advantage of Africans can be explained, at least in part, by this variant of the Duffy antigen,” says Planelles, who was not involved in the new study.