CD8A and coinfection: It is also critical to note that although many of the changes we observed in the overall CD8+ T cell subset were likely due to the outgrowth of HIV-specific cells, the differentiation in the overall CD8+ T cell subset may also be influenced by co-infection with other viruses, particularly cytomegalovirus (CMV), which is known to drive the expansion of CD8+ cells with a CD27−CD28−, and CD57+ phenotype [36], [37].