Matrine inhibits SGIV infection via regulation of the inflammatory and oxidative stress response

Matrine, a tetracyclic quinolizidine alkaloid derived from Sophora flavescens, exhibited antiviral activity against several mammalian viruses. Singapore grouper iridovirus (SGIV) is a highly pathogenic agent that seriously threatens the sustainable grouper industry, however, few efficient preventive measures were established up to now. Here, the antiviral effect of matrine against SGIV infection, and the potential mechanism underlying its antiviral action was investigated in vitro. Firstly, the effect of matrine on SGIV replication was evaluated by western blotting, quantitative PCR (qPCR) and viral titer assay, respectively. Matrine treatment reduced the expression levels of viral genes and viral progeny production in a dose-dependent manner. Moreover, matrine exerted more potent antiviral effect at the early stage of virus infection. Mechanistically, matrine treatment suppressed the inflammatory response induced by SGIV, evidenced by the decreased expression levels of the pro-inflammation factors. Moreover, SGIV infection-induced p65 phosphorylation was also markedly weakened by matrine treatment. Meanwhile, the reduction of antioxidant genes expression was reversed in SGIV infected cells after matrine treatment. In addition, matrine treatment up-regulated interferon (IFN) immune response in a dose-dependent manner. Taken together, our results suggested that matrine exerted antiviral activity against SGIV through both reducing inflammatory response and boosting cellular antioxidant activity and interferon response. Our findings suggested that matrine might serve as a potential antiviral agent for combating fish iridovirus infection.