Objective To investigate the effects of human α-defensin-5 (HD-5) against herpes simplex virus type 2 (HSV-2) in Vero cells cultured in vitro. Methods Cytotoxicity of HD-5 at various concentrations (10 to 200 μg/ml) on cultured Vero cells was determined by CCK-8 assay. HD-5 of 100 μg/ml was added into the culture medium of Vero cells before

simultaneously

or after the cells were infected with HSV-2. The effects of HD-5 against HSV-2 were analyzed by CCK-8 assay

and cytopathic effect (CPE) was observed at 72 h after HSV-2 infection. Meanwhile

the influence of serum concentration on the antiviral activity of HD-5 was also evaluated. Results No obvious cytotoxic effect of HD-5 was found in cultured Vero cells within the concentration of 100 μg/ml. At a fixed dose of 100 μg/ml

HD-5 showed significant protective effect on Vero cells against HSV-2 (P0.01)

when it was added before or simultaneously with HSV-2 infection. While

the protective effect was not observed when it was added in 2 h after HSV-2 infection (P0.05). The antiviral activity of HD-5 was markedly reduced as the concentration of serum in the medium was increased. Conclusion HD-5 has significant antiviral activity against HSV-2 in vitro

probably through reducing adherence and host cell invasion of the virus.