Gene Controls Production of Protein That Blocks HIV From Entering Cells; People With Extra Copies Protected, Study Says
Individuals who have extra copies of a gene that produces a specific protein are less likely to contract HIV or develop AIDS than people from the same ancestry who do not have extra copies of the gene, according to a study published in the Jan. 6 online issue of Science magazine, the AP/Las Vegas Sun reports (AP/Las Vegas Sun, 1/6). Dr. Sunil Ahuja of the University of Texas Health Science Center at San Antonio and colleagues studied blood samples from more than 4,300 HIV-positive and HIV-negative people with varying ancestral origins, according to Reuters (Fox, Reuters, 1/6). The researchers found that people who had more copies of a gene that produces the chemokine CCL3L1 -- a "sort of protein distress call from injured tissue" -- are less likely to be HIV-positive than people of the same ancestry who had fewer copies of the gene, according to the New York Times (McNeil, New York Times, 1/7). For each additional copy of the CCL3L1-producing gene that a person had beyond the average for their ancestral group, the risk of acquiring HIV was lowered by between 4.5% to 10.5%, according to the study (NIAID release, 1/6). HIV-negative African Americans had an average of four copies of the gene, while HIV-negative European Americans averaged two copies and HIV-negative Hispanic Americans averaged three copies (AP/Las Vegas Sun, 1/6). However, the findings do not indicate that one ancestral group is more susceptible to HIV infection than another (Reuters, 1/6). Researchers now know of 15 genetic traits that affect a person's susceptibility to HIV, the Times reports (New York Times, 1/7).
CCL3L1 is associated with a specific receptor on human cells, called CCR5, Reuters reports. HIV uses CCR5 to latch onto cells in order to enter them, according to Reuters (Reuters, 1/6). Previous studies have shown that people who lack CCR5 receptors because of genetic mutations rarely contract HIV (Kaiser Daily HIV/AIDS Report, 1/6). Researchers also found that individuals who had fewer copies of the CCL3L1-producing gene in addition to disease-acclerating CCR5 genetic variants were more likely to acquire HIV and have faster disease progression than people without such variants. "This work adds significantly to our understanding of the central role that molecules that interact with the CCR5 co-receptor play in influencing susceptibility to HIV/AIDS," Carl Dieffenbach, who oversees basic research at the National Institute of Allergy and Infectious Diseases Division of AIDS, said (NIAID release, 1/6).
"Individual risk of acquiring HIV and experiencing rapid disease progression is not uniform within populations," NIAID Director Dr. Anthony Fauci said, adding, "This important study identifies genetic factors of particular groups that either mitigate or enhance one's susceptibility to infection and disease onset" (AP/Las Vegas Sun, 1/6). Yusef Azad, director of policy and campaigns for the British advocacy group National AIDS Trust, said, "The research ... could well be an important step forward." He added, "We need the global community to provide the political commitment and funding necessary to ensure that all such avenues are fully pursued" (BBC News, 1/7).