Correspondence Short-course Raltegravir Intensification Does Not Increase 2 Long Terminal Repeat Episomal HIV-1 DNA in Patients on Effective

To the Editor—Controversy exists about whether human immunodeficiency virus type 1 (HIV-1) replication persists in patients receiving effective antiretroviral therapy. Residual viremia can often be detected in such patients by sensitive quantitative polymerase chain reaction assays, but the source of this viremia is unknown [1]. Possibilities include ongo-ing cycles of HIV-1 replication, long-lived HIV-1–infected cells that continuously or intermittently produce virus, or both. If residual plasma viremia is derived from ongoing HIV-1 replication, inten-sification of an effective regimen with another potent antiretroviral drug should lower viremia. Such treatment intensifi-cation studies have been conducted with different classes of antiretroviral agents (nucleoside reverse-transcriptase inhibi-tors, nonnucleoside reverse-transcriptase inhibitors, protease inhibitors, and the in-tegrase inhibitor raltegravir), and none has shown reduction in residual viremia [2–6]. However, Buzon et al [7] showed transient increases in episomal (2-Long Terminal Repeat [2-LTR] circle) HIV-1 DNA levels in 13 of 45 patients after raltegravir intensification, suggesting ral-tegravir blocked ongoing HIV-1 replica-tion without affecting plasma viremia. Moreover, Yukl et al [5] showed reduc-tions in unspliced HIV-1 RNA levels in CD41 T cells from the terminal ileum in 5 of 7 patients after raltegravir in-tensification. To provide additional insight into the effects of raltegravir in-tensification, we analyzed total HIV-1 DNA and 2-LTR circle levels in peripheral blood mononuclear cells (PBMCs) ob-tained before and after 28 days of ral-tegravir intensification from a study of 10 patients, published by McMahon et al [4] in Clinical Infectious Diseases, that showed no effect of raltegravir on residual viremia. Total cellular DNA was extracted (Dynabeads) from 5 3 106 PBMCs and assayed for total HIV-1 DNA and 2-LTR HIV-1 DNA circle levels by quantitative, real-time poly-merase chain reaction (limit of detection, 15 copies per 106 PBMCs for both as-says). HIV-1 DNA was detected in all sub-jects, ranging from 154 to 6,879 copies per 106 PBMCs and showing no con-sistent change between baseline (before intensification) and 28 days after in