HIV and Coevolution

In December of 2002, Mark E.J. Woolhouse (Centre for Immunology, Infection and Evolution, University of Edinburgh) published a paper entitled "Biological and biomedical implications of the co-evolution of pathogens and their hosts." The paper itself carefully defines co-evolution between host and pathogens, and how genetic variation and veterinary studies should more carefully be applied to the root core of co-evolution itself. In this paper, Woolhouse mentions that there "may be potential for molecular co-evolution between humans and HIV." The host's susceptibility to the HIV pathogen varies drastically, dependent on alleles that encode for the CCR5 receptor. This CCR5 receptor is a protein that lies on the surface of white blood cells - the cells that aid most specifically in immune responses (a factor that is largely impaired as a result of HIV infection). Woolhouse goes on to explain what exactly causes the CCR5 to become resistant - a deletion mutation caused by a pathogen "Yersinia pestis" - the same bacterium that causes the plague disease - and a few others. Variation of the HIV gene is linked to the variation of the infectivity of the different CCR5 receptors. Additionally, there is a coevolution between Cytotoxic T Lymphocyte responses and HIV-1, which also depends on genetic variation of pathogens.