Background: The human immunodeficiency virus (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 10 HIV-1-infected patients on antiretroviral therapy (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 versus LN (61/106 vs 104/106 CD4+ cells), and they 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 versus LN (4.3/106 vs 7.9/106), but they 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.