Recently, Heredia et al.[24]performed cell-cell fusion assays to examine the antiviral activity ofvicriviroc, a CCR5 antagonist in phase III trials (Gathe et al., Abstract #45LB 17th Conference on Retroviruses and Opportunistic Infections, 2010).They performed the assays with and without rapamycin, a drug that lowers theexpression level of CCR5 on cells [6] (Methods). This evidence concerns the gene CCR5 and Opportunistic infection.