Numerous studies have demonstrated that intensifying a suppressive ART regimen with an additional antiretroviral drug does not alter the frequency of latently infected cells or low-level viremia. However, in studies that have intensified ART with the integrase inhibitor raltegravir, an increase in circularised HIV episomes containing 2 copies of the viral long terminal repeat (2-LTR) circles within 2 weeks of intensification, was observed in ~30% of study participants. 2-LTR circles have a short half- life, which may explain why an increase in 2-LTR circles was only observed in studies that measured 2-LTR circles within 2 weeks of raltegravir intensification. In these two randomized controlled trials, the level of 2-LTR circles increased transiently in patients randomized to intensification with raltegravir as compared with placebo and this effect was more pronounced in subjects receiving a protease inhibitor (PI)-containing ART regimen. Other studies have failed to demonstrate an increase in 2-LTR circles following raltegravir intensification but this is likely because sampling was delayed beyond 2 weeks.