27 Jun 05

Laurence Gibson, Positive Nation In the maiden voyage for a novel technique to study the disease, researchers have found that the genes underlying HIV patients’ immune systems can predict their risk of progressing to Aids.

The new analysis showed the virus is less likely to progress in patients bearing rare immune system variants than in those with more common gene variants.

The researchers said the finding clarifies the interaction between HIV and patients’ immune defenses - and provides information that may ultimately help doctors tailor treatments to individual patients.

“Specific combinations of alleles [variations of a gene that differ slightly in structure and function] that humans carry, appear to protect against HIV,” said Thomas Kepler, from Duke’s University in Chicago.

“HIV-infected people who carry particular, rare gene variants have much lower viral loads than the other patients do,” he continued.

The study focused on 996 men, 562 of whom were HIV-positive. The researchers genetically screened participants’ blood samples for two immune system genes, HLA-A and HLA-B. 

HLA molecules orchestrate the response of the T-cells.

As immune system alleles are notoriously diverse, it was necessary for Kepler and his team to devise a novel statistical method to divide patients into disease progression groups.

“The method allowed us to exhaustively go through all possible gene partitions and assign a score to each, while avoiding the pitfalls of traditional methods of analysis,” Kepler stated.

The analysis of the patients revealed that “greater protection against HIV was afforded by rare immune system alleles” according to Kepler.

“That suggests that HIV has adapted to attack the dominant alleles in the population. In other words, the virus goes after the bigger target.”

By screening patients’ immune systems, doctors may eventually be able to identify those at the greatest risk of developing Aids – and prescribe accordingly