Fig. 5

PVRL4 inhibits viral-cellular membrane fusion. (A and B) HEK293T cells were contransfected with pMD2G, either PVRL4 or vector for 24 h and treated with low-pH PBS. And the syncytia formation was visualized by laser scanning confocal microscope, scale bar, 100 μm. (C and D) HEK293T cells expressing PVRL4 or vector were co-cultured with HEK293T cells expressing pMD2G at the ratio of 1:1 for 6 h before treated with acidic PBS. Note the formation of cell-cell fusion, scale bar, 100 μm. (E and F) WT or PVRL4^−/−HEK293T cells were transfected with pMD2G. At 24 h post-transfection, the cells were treated with low-pH PBS and the syncytium formation was visualized by laser scanning confocal microscope, scale bar, 100 μm. (G and J) PVRL4-overexpressing or control vector A549 cells and WT or PVRL4^−/−A549 cells were infected with HSV-1 (MOI = 0.01) for 24 h. The HSV-1 viral protein-mediated cell-cell membrane fusion was visualized by laser scanning confocal microscope, scale bar, 100 μm. Relative fusion was determined by normalizing the number of nuclei per syncytia under the experimental conditions to the control. Mean ± SEM of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, two-tailed Student’s t test