Inconsistent reversal of HIV-1 latency ex vivo by antigens of HIV-1, CMV, and other infectious agents

Abstract

Background A reservoir of replication-competent but latent virus is the main obstacle to a cure for HIV-1 infection. Much of this reservoir resides in memory CD4 T cells. We hypothesized that these cells can be reactivated with antigens from HIV-1 and other common pathogens to reverse latency. Results We obtained mononuclear cells from the peripheral blood of antiretroviral-treated patients with suppressed viremia. We tested pools of peptides and proteins derived from HIV-1 and from other pathogens including CMV for their ability to reverse latency ex vivo by activation of memory responses. We assessed activation of the CD4 T cells by measuring the up-regulation of cell-surface CD69. We assessed HIV-1 expression using two assays: a real-time PCR assay for virion-associated viral RNA and a droplet digital PCR assay for cell-associated, multiply spliced viral mRNA. Reversal of latency occurred in a minority of cells from some participants, but no single antigen induced HIV-1 expression ex vivo consistently. When reversal of latency was induced by a specific peptide pool or protein, the extent was proportionally greater than that of T cell activation. Conclusions In this group of patients in whom antiretroviral therapy was started during chronic infection, the latent reservoir does not appear to consistently reside in CD4 T cells of a predominant antigen-specificity. Peptide-antigens reversed HIV-1 latency ex vivo with modest and variable activity. When latency was reversed by specific peptides or proteins, it was proportionally greater than the extent of T cell activation, suggesting partial enrichment of the latent reservoir in cells of specific antigen-reactivity.

Cognate Antigen Engagement Induces HIV-1 Expression In CD4+T Cells From People On Long-Term ART

“…Although we found enrichment for total and intact HIV DNA within Agreactive cells in some participants, IPDA data showed striking heterogeneity across participants suggesting disparate distribution of proviruses among CD4 + T cells with distinct antigenic specificities. This notion that the latent reservoir does not reside in CD4 + T cells of only one subset or with recurring antigen specificities was suggested in earlier work 20,24,32,42 . Indeed, our data showed that HIV-1 can persist in memory CD4 + T cells of diverse Ag-specificity.…”

“…These findings suggested that infected cells are not commonly enriched in any particular population of Ag-specific memory cells. However, analysis was complicated by the rarity and heterogeneity of proviral populations across cells susceptible to different stimulations, which prevented the comparison between peptide pools and non-specific, positive controls (anti-CD3/CD28) 42 . Here, we used CMV and HIV-1 Gag as frequently encountered Ags and isolated CMV- and Gag-responding cells as previously described 36,45 .…”

“…We observed no significant difference in Gini index between stimulation with PMA/I and cognate Ag (Figure 5E) and the median percentage of sequences induced both with PMA/I and cognate Ag was 86.7% (Figure 5C). Importantly, the enrichment and expansion of Ag-responding cells allowed us to test different stimuli with aliquots of the same cell population with comparable infection frequency and composition of proviruses, something which was not possible in previous approaches 42,43 . Our results show that in enriched populations of Ag-reactive cells, the same proviruses can be induced by T cell activation with both cognate Ag and PMA/I.…”

“…Polyclonal stimuli acting through the TCR bypass this mechanosensing mechanism and may induce different transcriptional responses. Previous studies of Ag-driven latency reversal 42,43 have not used isolated Ag-responding cells and therefore cannot distinguish between direct Ag-mediated latency reversal and bystander T-cell activation. Here, to investigate the impact of Ag recognition on induction of HIV-1 gene expression in latently infected CD4 + T cells, we employed the ex vivo enrichment and expansion of CMV and HIV-1 Gag-reactive CD4 + T cells from people on ART.…”

Anti-HIV-1 ADCC and HIV-1 Env Can Be Partners in Reducing Latent HIV Reservoir

“…Many recent studies have shown that LRAs have a detrimental effect on the activity of CD8+ T cells and NK cells, resulting in impaired clearance of HIV infected cells (30,31). Since HIV-1 preferentially infects activated CD4 T cells (32) and activation of latently infected memory CD4 T cells by their cognate antigens is more specific, we propose that HIV antigens can be used as latency reversing agent (33). To the best of our knowledge, this approach for use the Env C peptides as latency reversing agent in resting memory cells is proposed only in our previous study (12) and the present study.…”