Lab Discovers More Complex Family Tree for HIV

In a development that could have a major effect on AIDS vaccine design, Los Alamos National Laboratory researchers have discovered that HIV variation is driven by more than a patient's immune response.

The common ancestry of HIV strains explains many mutational patterns that prompted the belief that the virus adapts in predictable ways in people with similar immune systems. But the researchers found that a virus' sequence is dictated not only by how it mutates to escape detection by a host's immune system, but also by the virus' common source and evolutionary track. This discovery can be applied to research on other viruses as well, including hepatitis, said Los Alamos' Bette Korber and Tanmoy Bhattacharya.

Common descent predicts viruses' similarity, such as HIV being transmitted among an IV drug-using group. According to Bhattacharya, the common source, rather than just similarities in the genetic structure of the hosts, may account for many commonalities among the viruses.

"In biology or any other system of evolving entities, when we try to find the relation between any characteristics and a mutational pattern like a viral change and the immune system of the person it finds itself in, one should never forget that the organisms haven't arisen at random but are descended from a common ancestor," said Bhattacharya.

Accounting for such viral lineages allows scientists to better understand how HIV adapts in the context of the human immune system, the researchers said. "The virus is changing in different people in different ways," said Korber. "This paper's main point is basic biology, understanding the relationship between host and virus."

The study, "Founder Effects in the Assessment of HIV Polymorphisms and HLA Allele Associations," was published in the magazine Science (2007;315(5818):1583-1586).

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