B5 Productive HIV-1 Infection of Cervical Tissue Ex Vivo

Abstract

Background The mucosal immune system of the lower female genital tract plays a key role in HIV-1 transmission and pathogenesis. We have developed an ex vivo system of cervical tissue (CT) explants that efficiently support HIV replication to better understand the role of lymphocytes and macrophages during HIV sexual transmission. Methods Multiparametric FACS analysis of the differentiation/activation of T lymphocytes and macrophages was performed in CT from HIV-1neg volunteers. Tissue blocks were infected with either R5-HIV-1BaL or X4-HIV-1LAI isolates. Productive infection of HIV-1 was documented by p24Gag, ELISA, by p24Gag intracellular staining, and by RT-PCR. Results CD4+ T cells showed a predominant effector memory (TEM) phenotype. CT macrophages expressed inflammatory surface markers and were positive for DC-SIGN and the mannose receptor. Tissue explants from all tested donors inoculated with R5 HIV-1BaL efficiently supported virus replication, whereas X4 HIV-1LAI replicated only in 4 out of 27 tissues that were enriched in CD27+CD28+ CD4 TEM cells. De novo HIV-1 replication rather than virus absorption was evident by suppression of viral replication by an RT inhibitor. After R5 HIV-1BaL infection, p24Gag+ was revealed in predominantly activated (CD38+) CD4+ T cells. Activation was also observed in p24Gagneg (bystander) CD4+ T cells. Moreover, R5 HIV-1BaL—infected macrophages were detected in 6/10 donors at late stage of infection, indicating the delay in virus replication by these cells compared to CD4+TEM cells. Conclusions CV explants efficiently support R5 HIV-1 infection while X4 HIV-1 did not replicate except in a few tissues, implying that CD4 and CXCR4 expression in target cells is not sufficient to support productive infection of X4 HIV-1. Furthermore, p24Gag+ cells were found predominantly among CD4+ TEM and macrophage subsets. CT explants represent a promising tool to dissect key events in HIV-1 transmission and pathogenesis.