Inhibition of HIV-1 transmission with and without Replens gel using the cervical culture model. The upper chamber of the Transwell with the cervical explant was exposed for 2 min to different concentrations of PVP-coated AgNPs (0.025, 0.05, 0.1 and 0.15 mg/mL), either alone or mixed with the Replens gel. After thoroughly washing extracellular PVP-coated AgNPs from the cervical explant, cell-free (HIV-1IIIB) [(5 × 105 TCID50)], or cell-associated virus (H9+) (5 × 105 cells) were added. To evaluate inhibition of the HIV-1 infection, indicator cells (MT-2) in the lower chamber were cultured and formation of syncytia was monitored for ten days. Graphs show values of the means ± standard deviations from three separate experiments. Graphs were created using the SigmaPlot 10.0 software.