Contribution of naive CD4+T cells to the intact HIV reservoir

Background: Recent findings suggest that na€ıve CD4 + T cells (TN) may contain a significant amount of replication-competent HIV DNA. We studied the contribution of different CD4 + T-cell subsets to the reservoir in two male Caucasian subjects on ART at approximately two and nine years after ART initiation, both virologically suppressed at the time of the donations. Methods: We sorted T CD4 + subsets from CD3 + CD8- PBMCs, defined as follows: na€ıve (CD45RA+, CCR7+, CD27+), central memory (CD45RA, CCR7+, CD27+), transitional memory (CD45RA, CCR7, CD27+), and effector memory (CD45RA, CCR7, CD27). Wemeasured total HIV DNA and sequenced 890 and 513 near full- length proviruses for Subject 1 and 2, respectively. Results: Among the subsets TN showed the highest percentage of intact proviruses. The contribution of TN to the intact reservoir was stable overtime, representing 38.5 and 34.7% for Subject 1 and 58.7 and 58.3% for Subject 2 at the two timepoints. The intact proviral sequences appeared to be mostly unique in TN while mostly clonal in effector memory cells (Figure 1). Conclusions: TN appear to contribute significantly to the intact reser- voir in two subjects followed on ART for nearly one decade.After reducing the clones, even a greater fraction of the reservoir was har- bored in TN. Given their long half-life and lower metabolic activity, the TN reservoir may represent a unique hurdle to HIV eradication. A limitation of our study is that the sorted TN population is a mixture of na€ıve, stem cell memory and T cells that have divided. In our opinion to sequence two individuals deeply at two time points provided us a better understanding of reservoir dynamics within subsets. Moreover, these individuals represent a spectrum of HIV infection. Subject 1 is a slow progressor with only CCR5-tropic proviruses while Subject 2 is a rapid progressor with a majority of CXCR4-tropic proviruses.