The International HIV Controllers Study is an international team of scientists dedicated to understanding HIV “controllers,” which are individuals that are infected with HIV but are somehow able to resist the virus without any medication. A new study by the group in Science finds that “controllers” share particular gene variants that appear to play an important role in regulating HIV resistance. From a summary in Discover Magazine:

After looking at over 1.3 million points around their genomes, the team found that just 313 separate the controllers from the other recruits. Amazingly, every single one of these variants sits within a specific part of our sixth chromosome, among a set of genes called class I HLA genes. The proteins they produce form part of the internal security checks that defend us from infections. They grab small pieces of other proteins from inside our cells and display them on the outside, waving them under the noses of passing T-cells. If the T-cells recognise these pieces as parts of bacteria, viruses or other foreign invaders, they tell the infected cell to self-destruct and set the immune system on red alert.

All of this depends on a single groove in the HLA proteins. This is the bit that embraces the pieces of other proteins and displays them so prominently to the immune system. If this groove isn’t structured correctly, our defenders don’t get an advanced warning about threats.

True enough, the team found that the groove of a single protein called HLA-B is especially important. At five positions in the groove, the HIV controllers have different amino acids than those whose disease progresses normally. These five amino acids aren’t the only things separating the controllers from the others, but they have a major impact.

Obviously, there’s still a lot of work to be done here, but these results are promising.

References

The International HIV Controllers Study (2010). The major genetic determinants of HIV-1 control affect HLA Class 1 peptide presentation. Science 330: 1551-1557.