Inducible HIV-1 Reservoir Reduction Assay (HIVRRA), a Fast and Sensitive Assay to Test Cytotoxicity and Potency of Cure Strategies to Reduce the Replication-Competent HIV-1 Reservoir in Ex Vivo PBMCs.

The HIV-1 reservoir, consisting of transcriptionally silent integrated HIV-1 proviruses, is a major barrier to a cure, as it persists during effective antiretroviral therapy (ART) and is the source of viral rebound upon treatment interruption. Some of the strategies explored for HIV cure focus on the identification of compounds to either reactivate and eliminate the HIV reservoir ("shock and kill") or to prevent HIV reservoir reactivation and induce deep proviral latency ("block and lock"). Paramount in developing these HIV-1 cure strategies is determining the effect of the compounds on the size of the inducible HIV-1 reservoir in blood from people living with HIV-1 (PWH). Traditionally, viral outgrowth assays have been the primary method to determine the inducible HIV-1 reservoir in CD4+ T cells from PWH. However, these assays are labor-intensive, time-consuming, and often have low sensitivity. We have recently developed the inducible HIV-1 reservoir reduction assay (HIVRRA), a rapid, cost-effective, and sensitive method to measure the impact of compounds on the inducible replication-competent HIV-1 reservoir in total peripheral blood mononuclear cells (PBMCs) from PWH ex vivo. The HIVRRA simultaneously evaluates the effect of test conditions on the size of the inducible replication-competent HIV-1 reservoir as well as the specificity and toxicity of the test strategy. Using total PBMCs instead of purified CD4+ T cells reduces processing time and resource requirements. This makes the HIVRRA a more practical, scalable tool for evaluating potential HIV-1 cure strategies. Key features • The HIVRRA builds on the TZM-BL cell-based assay to quantify the HIV-1 reservoir by Sanyal et al.'s [1] method. • The HIVRRA uses total PBMCs from PWH to determine infectious units per million cells. • The HIVRRA requires low PBMC input compared to other reservoir analysis methods. • The HIVRRA determines the toxicity of the compounds on HIV-1-infected and uninfected cells in the same assay.