The mutant genes that stymie HIV - mutation of two copies of gene that encodes for protein CC-CKR-5 linked to immunity to HIV infection - Biology - Brief Article

Science News, Nov 2, 1996

A new study confirms earlier reports that people with two mutant copies of a particular gene are largely resistant to infection by HIV, the virus that causes AIDS. More important, the study provides evidence that people who have just one mutant copy of the gene, although not protected from HIV infection, do take longer than usual to progress to AIDS.

The crucial gene encodes a protein called CC-CKR-5, which sits on the surface of immune cells and is used by HIV to infect the cells. People normally have two copies of the gene, but investigators have found that about 1 percent of the white population has a large deletion, or missing DNA segment, in both of their CC-CKR-5 genes. The most common strains of HIV cannot infect such people (SN: 8/17/96, p. 103).

After studying 1,955 people whose lifestyles put them at high risk for HIV infection, Stephen J. O'Brien of the National Cancer Institute in Frederick, Md., and his colleagues have found that those with the deletion in only one CC-CKR-5 gene enjoy no protection from HIV infection. Yet if infected, they generally survive several years longer than infected people with two normal genes, the team reports in the Sept. 27 Science.

O'Brien notes that about 20 percent of white people appear to harbor the deletion in at least one CC-CKR-5 gene. "That's more frequent than red hair. That kind of frequency doesn't arise randomly," he says. To explain why the deletion is now so common, O'Brien suggests that long ago, the relatively few Europeans who had the CC-CKR-5 deletion may have survived a version of AIDS or some other fatal illness that wiped out much of the population.