In this sense, although all memory CD4+ T cells are equally prone to infection by CCR5-tropic viruses, the proportion of proviruses carrying archival CCR5-using Env variants was clearly higher in the TEM+TD subsets at all the time points analyzed, despite the predominance of CXCR4-tropic viruses in the plasma virus population during virologic failure. This evidence concerns the gene CCR5 and infection.