Key gene in fight against HIV discovered

Scientists have located the genes central to the body's fight against HIV. Researchers believe that the discovery may shed light on why some sufferers survive years with HIV without exhibiting any symptoms, while others quickly develop Aids. It is also hoped that the breakthrough may be an important step towards the creation of an effective HIV vaccine.

The study, a joint project between the Universities of Oxford, Harvard and KwaZulu-Natal, collected data from HIV positive women in Durban, South Africa. It focused on human leucoctye antigens (HLA), the molecules that tell the immune system which cells have been infected by the disease and should be destroyed.

Of the three types of molecules under investigation, researchers found that type B genes identified those cells infected with HIV faster than type A or C genes. They also discovered that the subsequent speed of the virus' progression was dependent on what type of B gene each woman had. Women with the protective gene were more likely to survive longer and less likely to pass the virus onto their children.

However, scientists also found that the need to combat B type genes is driving the virus to develop faster as HIV is able to mutate rapidly to evade the defences of the human immune system.

The body's response is to develop more effective genetic variations, such as HLA-B, to attempt to tackle the virus, leaving obsolete variations incapable of fighting the infection to die out. This type of evolution would normally take thousands of years to develop, but the fight against HIV is driving genetic adaptation far more rapidly.

"The findings will help us understand precisely how the immune system can succeed or fail against HIV, a prerequisite for a rational approach towards design of an HIV vaccine," said lead researcher, Dr Philip Goulder. However, Jo Robinson, a senior treatment specialist at the HIV charity, Terrence Higgins Trust, stressed that society is still "many years away from having a vaccine for HIV."