Scientists said on Wednesday they have identified key genes involved in the body's response to HIV--a finding that could narrow the search for an effective vaccine against the deadly illness. A vaccine is considered the Holy Grail in the battle against the global AIDS epidemic, but efforts to find one have been hampered because of HIV's uncanny ability to mutate.
"We have narrowed down the focus of which particular genes are important in determining the outcome of HIV infection," said Philip Goulder of the Partners AIDS Research Center at Massachusetts General Hospital. "It tells us where to look, what to put into a vaccine in broad terms, and perhaps what needs to be excluded."
Goulder and his colleagues focused their research on genes called HLA-A, HLA-B, and HLA-C, which produce molecules that sit on the surface of cells. They tell the immune system's killer T cells when new viruses are produced within an infected cell and should be destroyed. The scientists said HLA-B genes are the key players in the body's response to infections, including HIV. "HLA-B is where all the action is," Goulder says. "Most vaccines take no account of the fundamental biological differences between HLA-A and HLA-B genes. These may be critical to the success or failure of a vaccine."
In research reported in the science journal Nature, the scientists studied blood samples from 375 HIV-positive patients in South Africa. They discovered that how well a patient's immune system
responded against HIV depended on their version of the HLA-B genes and had little to do with the other genes. "It is the responses that are generated through the HLA-B genes that are important," said Goulder.
The researchers also found that HIV-positive mothers who have a protective version of HLA-B were more likely to survive and less likely to pass on the virus to their children.
"This study identifies the genetic background where the struggle between HIV and the human immune system response occurs," said Goulder. "The findings will help in understanding precisely how the immune system can succeed or fail against HIV, a prerequisite for a rational approach towards design of an HIV vaccine."