Persistence of replication-competent HIV in both memory and naive CD4 T cell subsets in patients on prolonged and effective HAART

OBJECTIVE: To investigate the phenotypic features of infected lymphocytes in patients on prolonged and effective highly active antiretroviral therapy (HAART). DESIGN: We examined highly purified subsets of memory and naive CD4 T lymphocytes for the presence of replication-competent virus. METHODS: In 11 highly selected HAART-treated patients, we isolated highly purified CD45RO CD45RA CD4 T cells using a magnetic bead-based procedure. In some patients, a subsequent cell separation according to CD62L expression was performed. We quantified total viral DNA in freshly isolated T-cell subsets. To verify whether the virus was replication-competent, HIV RNA was measured in supernatants following cell activation. RESULTS: HIV DNA was detectable in the CD45RO and CD45RA CD4 T-cell subsets in 100% and 90% of the patients tested, respectively. In central memory CD45ROCD62L, effector memory CD45RO+CD62L-, truly naive CD45RACD62L, and CD45RA+CD62L- CD4 T cells, HIV DNA was found in 100%, 55%, 88%, and 50% of the patients tested respectively. HIV DNA was significantly higher in the CD45RO fraction than in the CD45RA subset and in the CD45ROCD62L fraction than in the three other CD45RA/ROCD62L+/- subsets. Detectable HIV RNA was found in the culture supernatants of CD45RO and CD45RA CD4 T-cell subsets in 80% and 66% of the patients tested respectively, and in CD45ROCD62L, CD45RO+CD62L-, CD45RACD62L, and CD45RA+CD62L- CD4 T cells in 100%, 100%, 100% and 50% of the patients tested respectively. CONCLUSIONS: In patients on prolonged and effective HAART, the pool of infected CD4 T lymphocytes consists predominantly of memory cells but also contains naive cells.