The antiviral effect and potential mechanism of matrine against white spot syndrome virus infection in crayfish (Procambarus clarkii)

White spot syndrome virus (WSSV), the causative agent of White spot disease (WSD), has caused high mortality and great economic losses in worldwide crustacean industries including shrimp and crayfish. Many bioactive components of Chinese herbs have been reported to be effective to control aquatic viral diseases including WSD. In this study, the antiviral effects of twelve herbal extracts were evaluated in WSSV-infected crayfish model, and Sophora flavescens extract exhibited the highest inhibition rate (87.63%) of WSSV replication. The anti-WSSV effect of matrine, the main bioactive component of S. flavescens, was further investigated. The results showed matrine could significantly inhibit WSSV replication in a dose-dependent manner and exhibited a robust inhibition rate (96.16%) with 50 mg/kg. Matrine both possessed potential preventive and therapeutic effects against WSSV infection and the preventive effect was better than the therapeutic effect. Besides, compared with the control, matrine significantly (p