AIDS / Ancient Epidemic Cited in Chimps’ Immunity

Dutch researchers theorize that an AIDS-like epidemic wiped out huge numbers of chimpanzees 2 million years ago, leaving modern chimps with resistance to the AIDS virus and its variants. If true, the hypothesis would explain why chimps, who share more than 98% of their DNA in common with humans, don’t develop AIDS.

The theory stems from a study of DNA in 35 chimps conducted by the Biomedical Primate Research Center in the Netherlands.

The chimps in the study shared an unusually uniform cluster of genes in the area that controls their immune systems’ defenses against disease. “Chimps show more genetic variation than humans in all areas--with this one exception, which is seriously condensed,” said Dr. Ronald Bontrop, who led the Dutch team that worked with statisticians from the University of California.

The findings will be published in the Proceedings of the National Academy of the Sciences of the United States of America.

Bontrop said that the chimps’ lack of genetic diversity in that area suggests that a lethal sickness attacked chimps in the distant past. This unknown disease would have wiped out all or almost all chimps that didn’t have the right immune system genes to fend it off, leaving the survivors with a uniform set.