The last time I wrote about HIV, I made the point that biology is all about shape; keep that idea in mind and a lot of things will suddenly start making a lot of sense. In that instance, I was writing about antibodies that were able to nearly universally attack HIV based upon one particular location on the virus which did not change shape. In this post I want to talk about a new study concerning protein differences.
To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and analyzed the effects of individual amino acids within the classical HLA proteins
HIV controllers are just what you probably think they are: they are people whose bodies are able to control the impact of HIV. They maintain healthy levels of helper T Cells. Progressors, on the other hand, are people who follow the expected course after they contract HIV. In this study, a large group of controllers were taken and had their genomes compared to progressor genomes. Researchers found more than 300 (313, to be exact) SNPs on the chromosome 6 that separated these two groups.
This is a pretty specific area with a small amount of difference. In fact, on the HLA-B protein, a difference of just 5 amino acids makes all the difference in a single groove. It appears as though this is one of the most important differences between controllers and progressors, constituting a significant region which enables the immune system to control and limit the proliferation of HIV. The amino acid sequence changes the shape of the groove in controllers as compared to progressors. This change protects the controller against HIV and its deadly consequences.
Precisely how this change in shape keeps HIV from turning into AIDS has not yet been made clear, but it is very promising. Given the current state of research, I’m willing to predict we’ll see a cure for HIV before we see a cure for cancer.