Evaluation of emodin's antiviral activity against Chinese rice-field eel rhabdovirus infection in Monopterus albus.

Abstract

Infection with Chinese rice-field eels rhabdovirus (CrERV) causes significant economic losses in Chinese rice-field eels aquaculture. This study investigated the antiviral potential of herbal compounds against CrERV. Screening 41 compounds in vitro identified ten that suppressed CrERV proliferation by over 50%. Emodin was the most effective, demonstrating a dose-dependent inhibition with a maximum rate of 86.7%. It significantly alleviated virus-induced cytopathic effects and maintained cell viability. Dose-and time-dependent experiments and viral binding assays revealed that emodin does not block viral attachment but acts during the middle and late stages of viral replication. Furthermore, emodin effectively attenuated CrERV-induced apoptosis, as evidenced by the suppression of nuclear condensation and apoptotic body formation. In vivo experiments, treatment with emodin significantly improved the survival rates of infected eels by 66.67%. It also reduced viral loads in liver and kidney tissues and alleviated histopathological damage. The proposed mechanism involves the activation of the AMPK signaling pathway and subsequent modulation of its downstream targets, PPARα and SREBP-1c. In this study, emodin exhibits potent anti-CrERV activity both in vitro and in vivo, representing a promising therapeutic candidate for controlling CrERV-associated diseases in aquaculture.