TGFB1 and infection: Having demonstrated that the expression of DC-SIGN on DC is decreased by CM (Figure 1) and TGF-β1 (Figure 2), we examined the effect of DC-SIGN blockade on trans infection of viruses expressing reference and transmitted/founder envs. For these experiments, DC were pre-pretreated with antibody to DC-SIGN prior to incubation with HIV-1.