Research on a group of HIV infected men shows that individuals with rare forms of a highly variable class of immune molecules are best able to control infection – those with the most common forms have higher amounts of virus in their blood.
HLA class I molecules bind to peptides from invading pathogens and present them to T cells of the immune system. Previous studies have linked HIV susceptibility to certain types of HLA class I molecules. Now Steven Wolinksy and colleagues find a pattern to such susceptibility. The investigators report in the July issue of Nature Medicine that the presence of rare HLA class I types correlates with low viral load, and the presence of the most common HLA class I types correlates with high viral load. The results suggest that HIV-1 may have evolved to evade the immune system in individuals with the most common types of HLA class I molecules.
The study predicts that, on a population level, HIV disease outcome would depend in part on the frequencies of different HLA class I types. The investigators also predict that racial groups underrepresented in an epidemic region, and so likely to have locally rare types of HLA class I, would best counteract the virus. They note that, of the over 500 from the Chicago study, black men had lower amounts of virus in their bloodstream.
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