Similar frequency and inducibility of intact HIV-1 proviruses in blood and lymph nodes.

Background The HIV-1 latent reservoir (LR) in resting CD4 + T cells is a barrier to cure. LR measurements are commonly performed on blood samples and therefore may miss latently infected cells residing in tissues, including lymph nodes. Methods We determined the frequency of intact HIV-1 proviruses and proviral inducibility in matched peripheral blood (PB) and lymph node (LN) samples from ten HIV-1-infected patients on ART using the intact proviral DNA assay and a novel quantitative viral induction assay. Prominent viral sequences from induced viral RNA were characterized using a next-generation sequencing assay. Results The frequencies of CD4 + T cells with intact proviruses were not significantly different in PB vs LN (61vs104/10 6CD4 + cells), and were substantially lower than frequencies of CD4 + T cells with defective proviruses. The frequencies of CD4 + T cells induced to produce high levels of viral RNA were not significantly different in PB vs LN (4.3/10 6 vs 7.9/10 6), but were 14-fold lower than the frequencies of cells with intact proviruses. Sequencing of HIV-1 RNA from induced proviruses revealed comparable sequences in paired PB and LN samples. Conclusions These results further support the use of PB as an appropriate proxy for the HIV-1 LR in secondary lymphoid organs.