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 < 0.01) improved the survival rate of WSSV-infected crayfish (from 0% to 48.57% on 10th day), notably ( p < 0.01) suppressed the expression of virus replication-related genes ie1 , DNApol and Vp28 , remarkably ( p < 0.01) activated C-type lectin ( CTL ) and prophenoloxidase ( ProPo ) and inhibited barrier-to-autointegration ( BAF ) expression to improve crayfish innate immunity against WSSV infection, up-regualated the CAT and GST expression and down-regulated the expression of NF-κB , cyclooxygenases COX-1 and COX-2 genes to balance the oxidative stress and inflammatory injury caused by WSSV. This study will provide a theoretical basis for the development of matrine as an efficient and practical anti-WSSV drugs and meaningful reference for the study of antiviral effect of matrine on other aquatic animal viruses. • Matrine exhibited 96.16% inhibition rate against WSSV replication at 24 h post infection; • Matrine conferred the preventive and therapeutic effects against WSSV infection; • Matrine suppressed the expression of replication-related genes ie1 , DNApol and Vp28 to inhibit WSSV replication; • Matrine enhanced the CTL and ProPo expression to improve crayfish innate immunity against WSSV infection. • Matrine increased the CAT and GST expression and deceased the COX-1 and COX-2 expression to balance the oxidative stress and inflammatory injury caused by WSSV.