Reliable and reproducible LightCycler qPCR for HIV-1 DNA 2-LTR circles.

Highly active anti-retroviral therapy (HAART) has reduced the plasma load of HIV-1 to undetectable levels. It has however failed to eliminate the virus from other body compartments. Current methods for monitoring persistent viral replication in HIV-1+ patients require a large amount of blood and/or repeated tissue biopsies. Furthermore, some of the viral reservoirs, such as brain and eye, are inaccessible for sampling. The detection of episomal HIV-1 DNA 2-LTR circles in CD4+ cells is indicative of recent, acute infection events. This paper describes a reliable and reproducible LightCycler-based assay for the quantitative measurement of HIV-1 DNA 2-LTR circles in human peripheral blood mononuclear (PBMN) cells. It details the modifications to the DNA extraction procedure and to the LightCycler PCR procedure that were required to achieve this. This new surrogate marker of persistent viral replication can now be reliably, reproducibly and robustly used to study the clinical progress of large numbers of patients whose plasma HIV-1 RNA has been reduced to undetectable levels by anti-retroviral drugs.