Relationship Between Cd4 T Cell Turnover, Cellular Differentiation And Hiv Persistence During Art

The precise role of CD4 T cell turnover in maintaining HIV persistence during antiretroviral therapy (ART) has not yet been well characterized. In resting CD4 T cell subpopulations from 24 HIV-infected ART-suppressed and 6 HIV-uninfected individuals, we directly measured cellular turnover by heavy water labeling, HIV reservoir size by integrated HIV-DNA (intDNA) and cell-associated HIV-RNA (caRNA), and HIV reservoir clonality by proviral integration site sequencing. Compared to HIV-negatives, ART-suppressed individuals had similar fractional replacement rates in all subpopulations, but lower absolute proliferation rates of all subpopulations other than effector memory (TEM) cells, and lower plasma IL-7 levels (p = 0.0004). Median CD4 T cell half-lives decreased with cell differentiation from naive to TEM cells (3 years to 3 months, p<0.001). TEM had the fastest replacement rates, were most highly enriched for intDNA and caRNA, and contained the most clonal proviral expansion. Clonal proviruses detected in less mature subpopulations were more expanded in TEM, suggesting that they were maintained through cell differentiation. Earlier ART initiation was associated with lower levels of intDNA, caRNA and fractional replacement rates. In conclusion, circulating integrated HIV proviruses appear to be maintained both by slow turnover of immature CD4 subpopulations, and by clonal expansion as well as cell differentiation into effector cells with faster replacement rates.Author summaryHIV infection is a life-long disease for which we do not currently have a cure. One reason for this is that the virus goes into a dormant state and hides in CD4 T cell lymphocytes. Many of the less mature infected cells slowly self-renew (i.e., replace themselves) over time, whereas other types of infected cells rapidly proliferate and expand, and are replaced more rapidly. In our study, we directly measured how rapidly different types of CD4 T cells divide in treated people with HIV. In addition to confirming that less mature CD4 T cell populations self-renew at a very slow rate, and that more mature cells proliferate and expand at a more rapid rate, we also found that cell types that divide more rapidly are more likely to contain HIV. By carefully defining how rapidly these different cell populations are replaced, we help inform studies of HIV cure interventions that specifically target these discrete populations of HIV-infected cells.