Additive effect of HCMV gB peptides 174-200 and 233-263 on HCMV infection. HFF were seeded at a density of 3.5×105 cells in each well of a 24-well plate 24 hours prior to infection. The ability of peptides 174-200 and 233-263 to work together and their effect on inhibition of virus infection was evaluated by infecting human foreskin fibroblasts (HFF) with the Towne-GFP strain of HCMV (0.5 MOI) preincubated with different concentrations of inhibitory peptides at 37°C for 90 minutes. GFP-positive cells were visualized 48 hours post-infection by fluorescence microscopy and then quantified using flow cytometry. Significant reductions in the number of GFP-positive cells compared to HCMV infected cells are denoted by a * (p < 0.05), ** (p < 0.01), and *** (p < 0.001, determined using one-way ANOVA and Tukey's post test). All structural figures of HSV-1 gB in the post-fusion configuration were generated using MacPyMOL  and FreeHand (Macromedia). Different domains of gB are shown in the ribbon structures: yellow-fusion domain II, purple-stem, green-domain I, and blue-domain III with extended α-helices, which are involved in trimerization. Peptides targeting different domains of HSV-1 gB that correspond to HCMV gB domains are shown in black.