Towards an HIV-1 cure: measuring the latent reservoir

•A high-throughput and well-validated assay is needed to accurately measure the HIV-1 LR.•PCR-based assays overestimate the size of the LR.•Culture-based assays underestimate the size of the LR.•No two HIV-1 eradication clinical trials use the same measurement.

The latent reservoir (LR) of HIV-1 in resting memory CD4+ T cells serves as a major barrier to curing HIV-1 infection. While many PCR- and culture-based assays have been used to measure the size of the LR, correlation between results of different assays is poor and recent studies indicate that no available assay provides an accurate measurement of reservoir size. The discrepancies between assays are a hurdle to clinical trials that aim to measure the efficacy of HIV-1 eradication strategies. Here we describe the advantages and disadvantages of various approaches to measuring the LR.