Screening Of Anti-enterovirus71and Coxsackievirus A16Inhibitors Through Reporter Viruses And Cell Viability-based Method

Hand, foot and mouth disease (HFMD) is a common pediatric illness mainly causedby infection with enterovirus71(EV71) and coxsackievirus A16(CA16). Thefrequent HFMD outbreaks are among the most pressing health concerns in theWestern Pacific region. Currently, no vaccine or antiviral drug for EV71/CA16infections has been approved, effective antiviral therapies against EV71and CA16infections are urgently needed. In this study, a two-step screening platform consistingof reporter virus-based assays and cell viability-based assays was developed toidentify potential inhibitors of EV71/CA16infection. Two types of reporter viruses, apseudovirus containing luciferase-encoding RNA replicons encapsidated by viralcapsid proteins and a full-length reporter virus containing enhanced green fluorescentprotein, were used for primary screen of400highly purified natural compounds.Thereafter, a cell viability-based secondary screen was performed for the identifiedhits to confirm their antiviral activities. Three small molecules (luteolin, galangin andquercetin) were identified, among them luteolin exhibited the most potent inhibition ofviral infection. In the cytopathic effect (CPE) reduction assay and plaque reductionassay, luteolin showed similar50%inhibitory concentration (IC50) values of about10μM. Luteolin targets the post-attachment stage of EV71and CA16infection byinhibiting viral RNA replication. These findings suggest luteolin may serve as a baseflavonoid to develop potent anti-EV71and CA16drugs.