Fig. 4.

Downregulation of syndecan-1 and syndecan-2 affects HSV-1 plaque formation, size and enhances cell survival in HeLa cells. Cells were either mock treated (no transfection), or treated with scrambled siRNA, syndecan-1 siRNA or syndecan-2 siRNA. Post-transfection cells (48 h) were infected with HSV-1(KOS) (m.o.i. of 0.01). (a) Post-infection infectivity at 72 h was measured by the number of p.f.u. Relative number of plaques was computed relative to mock-treated (no transfection) samples. Significant decreases of number of plaques were seen in both syndecan-1 siRNA- and syndecan-2 siRNA-transfected HeLa cells. Plaques that consisted of 15 or more nuclei were counted. Results are means±sd of four independent experiments conducted in triplicate (**P<0.0001). (b) Morphological appearance of Giemsa-stained HSV-1 (KOS) plaques 72 h post-infection. In syndecan-1 siRNA- and syndecan-2 siRNA-treated HeLa cells smaller plaques were observed compared with the plaques in mock-treated or scrambled siRNA-treated cells. Magnification, ×40. (c) Cytotoxicity was measured after 120 h HSV-1 (KOS) infection. Relative number of dead cells was calculated relative to mock-treated samples. Significant decreases of cytotoxicity were observed in both syndecan-1 siRNA- and syndecan-2 siRNA-treated cells; however, only the effect of syndecan-2 siRNA treatment was statistically significant. Results are means±sd of four independent experiments conducted in triplicate (*P<0.05).