CD4 and infection: The reduced suppressive effect of IDV treatment on HIV-1 transmission by lamina-propria derived cells (Fig 2F) and direct infection of U87.CD4.CCR5 cells [S1 Fig], as assessed by intracellular HIV-1 capsid p24 protein expression, is attributed to IDV’s inhibition of extracellular release of mature HIV-1 virions rather than directly interfering on earlier steps of HIV-1 replication cycle, such as translation of viral capsid protein [35].