TGFB1 and infection: We report in this study that: 1) UEC secretions down-regulate DC-SIGN expression on DC via a TGF-β-dependent mechanism, 2) UEC suppress the trans infection of both reference and transmitted/founder HIV-1, and 3) Recombinant TGF- β1 exerts a differential inhibitory effect in that it inhibits trans infection of reference HIV-1 but has minimal inhibitory effect on trans infection of transmitted/founder HIV-1 variants tested here.