In vivo and in vitro antiviral effect and mechanisms of rhein against nervous necrosis virus

Viral nervous necrosis (VNN) caused by nervous necrosis virus (NNV) is a major threat to the global aquaculture industry, resulting in huge economic losses. In this study, we evaluated a naturally anthraquinone, rhein, as a potential therapeutic agent against NNV. Rhein effectively inhibited NNV-induced cytopathic effects (CPE) at a concentration of 18.84 mu M, with an inhibitory concentration (IC50) against NNV replication of 8.77 mu M. More -over, the study revealed a possible anti-NNV mechanism. Rhein could disrupt NNV-induced S-phase cell cycle arrest by inhibiting ATP synthesis, and cell cycle arrested in S phase is favorable for NNV replication, which in turn inhibits NNV replication. The therapeutic effect of rhein was also evaluated in vivo, where the survival rate of NNV infected grouper was increased by 26.7% with the treatment of 10 mg/kg rhein. Our findings demonstrated the potential of rhein as a pharmacological compound that exerts significant antiviral activity against NNV by modulating the cell cycle and ATP synthesis. Consequently, rhein has shown significant promise as a medication for the prevention and treatment of viral infections in aquaculture.