CD4 and HIV-1 infection: 9,12–14 To probe pathways that may be involved in gut mucosal HIV-1 pathogenesis, we recently performed unbiased transcriptomics to profile LP CD4 T cell gene expression following in vitro exposure to enteric commensal Prevotella stercorea in the presence or absence of experimental HIV-1 infection.15 We observed that exposure of LPMC to enteric bacteria induced significant Granzyme A (GZA) and GZB expression in gut CD4 T cells, and the expression of these granzymes was further enhanced in the presence of replicating HIV-1.