Antiretroviral therapy (ART) provides effective control of human immunodeficiency virus (HIV) replication and maintains viral loads of HIV at undetectable levels. Interruption of ART causes rapid recrudescence of HIV plasma viremia due to reactivation of latently HIV-infected cells. Here, we characterize the timing of both the initial and subsequent successful viral reactivations following ART interruption in macaques infected with simian immunodeficiency virus (SIV). We compare these to previous results from HIV-infected patients. We find that on average the time until the first successful viral reactivation event is longer than the time between subsequent reactivations. Based on this result, we hypothesize that the reactivation frequency of both HIV and SIV may fluctuate over time, and that this may impact the treatment of HIV. We develop a stochastic model incorporating fluctuations in the frequency of viral reactivation following ART interruption that shows behaviours consistent with the observed data. Furthermore, we show that one of the impacts of a fluctuating reactivation frequency would be to significantly reduce the efficacy of 'anti-latency' interventions for HIV that aim to reduce the frequency of reactivation. It is therefore essential to consider the possibility of a fluctuating reactivation frequency when assessing the impact of such intervention strategies.
Keywords: human immunodeficiency virus; latency; mathematical biology; mathematical modelling; viral reactivation.