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A huge international consortium examined the genetic factors involved in individual variation in ability to control viral spread following infection by Human Immunodeficiency Virus (HIV). 

A small subset of people infected with HIV show the ability to significantly limit viral replication and spread to over a long period in the absence of treatment, preventing progression to clinical AIDS. Researchers performed a genomewide association study (GWAS) on a total of 974 of these HIV-controllers and 2648 HIV-progressors, none of whom had received treatment, from different populations. 

Every SNP that showed significant association with HIV control lay within the major histocompatibility complex (MHC) region on chromosome 6, clustered around the class I HLA genes. Analysis suggested that the genetic variants observed in controllers all affected a small number of amino acids in the HLA proteins, involved in presentation of viral proteins to components of the immune system.

The authors conclude that physical interactions between the viral peptides and the host HLA proteins are a key factor in effective control of viral infection by the immune system, and that genetic variation affecting these interactions underlies the major part of human variability in response to HIV infection. 

Despite some success in developing therapeutics to control HIV infection, a vaccine remains an urgent health need around the world. Pathological insights provided by genetic analysis such as this could ultimately be pivotal in efforts to devise effective interventions to block or limit HIV infection.