Exploring the antiviral potential of paeonol from medicinal plants: A promising strategy for controlling white spot syndrome virus

The outbreak of white spot disease (SD) caused by White Spot Syndrome Virus (WSSV) has resulted in significant losses in crustacean aquaculture. However, effective measures to control this infectious viral disease are currently lacking. In this study, we screened 15 medicinal plants for their inhibitory activity against WSSV. The results showed that extracts from Paeonia x suffruticosa Andr. (Mu Dan) and Salvia miltiorrhiza Bunge (Dan Shen) exhibited good inhibitory activity against WSSV, with their main component paeonol showing high activity (92.53%, 75 mg/kg). Paeonol demonstrated concentration-dependent reductions in viral load and viral gene transcription levels, leading to enhanced survival rates in WSSV-infected crayfish across various administration routes. Co-incubation experiments demonstrated that paeonol did not affect the infectivity of WSSV particles, but it exhibited significant inhibitory effects on the viral load in crayfish before and after treatment. Mechanistically, paeonol regulated the host's immune function by balancing oxidative stress, reducing inflammatory damage, and normalizing protein levels, thereby inhibiting WSSV replication in various organs of crayfish. Moreover, in a static cohabitation model, paeonol effectively hindered the horizontal transmission of WSSV from infected donor crayfish to healthy individuals. In conclusion, considering the simple structure and ease of synthesis of paeonol, this study provides important theoretical evidence for the development of paeonol as an environmentally friendly and cost-effective drug for controlling WSSV outbreaks in crustacean aquaculture.