Genetic variations that might help people newly diagnosed with HIV control their viral loads also could be causing a mutation in the virus that makes it less potent, according to a study published Friday in PLoS Pathogens, Reuters reports.

Some people have versions of an immune system gene, called HLA, that are "known to force HIV to tolerate mutations that damage its ability to reproduce," according to Carolyn Williamson of the Centre for the AIDS Programme of Research in South Africa and colleagues. The weakened virus also means lower viral loads and slower disease progression in people with beneficial versions of HLA, according to Reuters. The researchers found that the weakened virus might be transmitted to and act in the same way in other people, even if they do not have the HLA variation, Williamson said.

The researchers followed 21 women in South Africa who recently contracted a weakened strain of HIV. The women did not have the beneficial HLA variation, according to Reuters. The researchers followed the women for between one to three years, Reuters reports. The researchers found the women had much lower viral loads, compared with people carrying a strain of HIV that had not mutated to a weakened state. The researchers also found that while the women's viral loads decreased, their CD4+ T cell counts increased. "It is pretty well established if you have certain HLA genes, you are better off," Williamson said, adding, "It is very likely that the virus in the people who did not have the HLA gene came from individuals who did."

According to Williamson, the "significant difference to other studies is that this is showing the actual benefit is due to the genetic composition of the virus." She added that the findings show "a survival advantage with a virus containing specific genetic signatures associated with lower replication."

The researchers have not studied the women to see how much slower they progress to AIDS but noted the findings could help researchers looking for an effective vaccine through an improved understanding of why some people living with the virus survive longer (Kahn, Reuters, 3/20).

The study is available online.