Scientists have pinpointed three genes that help some HIV-infected people rein in the virus and postpone the onset of AIDS in a finding that may help guide vaccine and drug development, they said Thursday.

They identified variations in the three genes that may help the immune systems of some people control the virus while others fail to control HIV proliferation.

The international team of researchers scanned the genomes of 486 HIV-infected people from Switzerland, Italy, Britain, Australia, Spain and Denmark.

AIDS is an incurable disease in which the virus damages the immune system, the body's natural defender.

In early stages of HIV infection before the virus has had time to cause full-blown AIDS, there is a battle between the virus and the immune system, which deploys key immune cells to try to prevent HIV from multiplying out of control. The immune system's success varies tremendously from person to person.

"What you'd like to do is understand why some people's immune system can push the virus down to really low levels and others can't. And you would try to capitalize on that with a vaccine strategy," Duke University geneticist David Goldstein, who led the research, said in a telephone interview.

"This has really been a treasure trove in terms of pointers to new directions for research," Goldstein added.

The research was published in the journal Science.


SEARCH FOR GENES

Scientists in recent years have been performing genome-wide searches for genes implicated in various diseases. This marked the first time such a study was done involving the human immunodeficiency virus, which causes AIDS, or any infectious disease, Goldstein said.

The genetic analysis was done at Duke University in Durham, North Carolina, and the University of Lausanne in Switzerland.

The researchers hope identifying these three genes can help guide efforts to create an effective HIV vaccine that works by turning up the protective actions of these genes to make the body's immune system better fight HIV infection.

They also hope the information can help in the development of drugs that may mimic what these genes are doing to interfere with HIV.

One of the three genes, called HLA-C, appears to be a rather good potential vaccine target, Goldstein said. While HIV is able to shut down a related gene, Goldstein added, the virus does not appear to be able to do so to this one, suggesting HLA-C may expose a vulnerability of HIV.

The gene is involved in a system involved in pinpointing bodily invaders and identifying them for destruction.

Another of the genes, called HCP5, has a fairly rare version that appears to lead to better control of HIV.

This gene, Goldstein said, is the remnants of a retrovirus -- HIV also is a retrovirus -- that entered the genome of human ancestors millions of years ago and became decommissioned.

It has some genetic similarity to HIV. "And because of that, it actually could be interfering with the functioning of those HIV genes. So that is an exciting possibility," he said.

Goldstein said further genome-wide testing is underway to try to find other genes relevant in the effort to thwart HIV.