A highly multiplexed droplet digital PCR assay to measure the intact HIV-1 proviral reservoir.

Levy, Claire N; Hughes, Sean M; Roychoudhury, Pavitra; Reeves, Daniel B; Amstuz, Chelsea; Zhu, Haiying; Huang, Meei-Li; Wei, Yulun et al. · Cell Rep Med · 2021

basic_science · Level V

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Abstract

Quantifying the replication-competent HIV reservoir is essential for evaluating curative strategies. Viral outgrowth assays (VOAs) underestimate the reservoir because they fail to induce all replication-competent proviruses. Single- or double-region HIV DNA assays overestimate it because they fail to exclude many defective proviruses. We designed two triplex droplet digital PCR assays, each with 2 unique targets and 1 in common, and normalize the results to PCR-based T cell counts. Both HIV assays are specific, sensitive, and reproducible. Together, they estimate the number of proviruses containing all five primer-probe regions. Our 5-target results are on average 12.1-fold higher than and correlate with paired quantitative VOA (Spearman's ρ = 0.48) but estimate a markedly smaller reservoir than previous DNA assays. In patients on antiretroviral therapy, decay rates in blood CD4<sup>+</sup> T cells are faster for intact than for defective proviruses, and intact provirus frequencies are similar in mucosal and circulating T cells.

Medical subject headings