Study on the inhibitory effect of rocaglamide against Micropterus salmoides rhabdovirus (MSRV)

Micropterus salmoides rhabdovirus (MSRV) is a pathogen that has severely limited the development of largemouth bass aquaculture in recent years. The MSRV infection often accompanies with huge economic losses since there is no effective treatment available. Rocaglamide (Roc-A) is a natural product extracted from plants of the genus Aglaia and known to be an effective drug in combating a variety of mammalian viruses. In this study, the anti-MSRV effect of Roc-A was tested by using different experimental methods including cytopathic effect (CPE) production, plaque formation assay and real-time quantitative PCR (qRT-PCR) analysis. The results revealed that Roc-A has no obvious preventive effect on MSRV infection, but could effectively inhibit the infectivity of MSRV in EPC cells in vitro. In vivo test confirmed the therapeutic effect of the Roc-A on largemouth bass infected with MSRV. Intraperitoneal injection of 0.25 mg/kg Roc-A could effectively increase the survival rate of largemouth bass by 37%. Histopathological analysis of affected fish showed that Roc-A effectively avoided tissue damage caused by MSRV. Roc-A effectively reduced the expression level of MSRV-G in liver, kidney and spleen after virus infection by qRT-PCR (P < 0.001). In conclusion, both in vivo and in vitro experiments proved the potential therapeutic effect of Roc-A on MSRV infection. Our new findings may lay a new foundation for more in-dept study for enhanced understanding of the mechanism of Roc-A against MSRV and facilitating the development of new anti-MSRV drugs.