This is consistent with the observation that CCR5 is predominantly expressed on CD45RA− antigen-primed memory cells which are known to have higher turnover rates than their naïve counterparts.[19], [21] In the context of HIV infection, this will render CCR5+ cells more susceptible to HIV infection and also more likely to be the source of circulating virus in infected individuals, consistent with a proliferation-based model of early R5-predominance.[17] Concurrently, CCR5+ cells represent the subpopulation whose turnover rate is most affected by HIV infection. This evidence concerns the gene CCR5 and HIV infectious disease.