Hoveniae Semen Seu Fructus water extract inhibits influenza A virus infection

Hoveniae Semen Seu Fructus (HSF) is a fruit and seed of Hovenia dulcis Thunb. Here, we first report HSF water extract contains a potent anti-influenza A virus (IAV) effect via inhibition of neuraminidase and hemagglutinin and a direct virus-killing effect. We examined the effect of WHSF on IAV infection using GFP-tagged Influenza A/PR/8/34. FACS analysis and fluorescent microscopy showed a dose-dependent inhibitory effect of WHSF against IAV infection. WHSF also suppressed the cytopathic effects of H1N1 and H3N2 IAV. Immunofluorescence and qPCR analyses confirmed WHSF significantly decreases IAV protein and RNA expressions. Time of addition and plaque assays revealed WHSF affects viral replication in the early stage via modulating hemagglutinin and inducing virucidal effects. Furthermore, WHSF suppressed the neuraminidase activity of H1N1 and H3N2 IAV. Quercetin, not taxifolin in WHSF inhibited IAV infection. Our results suggest WHSF could be developed as a natural antiviral agent to prevent IAV infection.