Antiviral activity of geniposidic acid against white spot syndrome virus replication in red swamp crayfish Procambarus clarkii

White spot syndrome virus (WSSV) causes high mortality in crustacean, but there are no effective therapies up to now. Medicinal plants and their bioactive ingredients are important sources of therapeutic agents. In the study, the anti-WSSV activities of 10 plant extracts were investigated in crayfish Procambarus clarkii. The results showed that the ethanol extracts of Eucommia ulmoides Oliver had the highest inhibition on WSSV replication among these tested extracts, with 84.12%. Geniposidic acid (GPA) is a major active ingredient of E. ulmoides. The contents of GPA in ethanol extracts of E. ulmoides were 32.148 mg/g. GPA could also suppress WSSV infection in vitro and in vivo. The inhibition rate was over 97% after treatment with 50 mg/kg GPA for 24 h. In addition, the mortality of WSSV-infected crayfish treated with GPA was 56.67%, while it was 100% for the controls. GPA possessed anti-inflammatory and anti-oxidative activities in crayfish. Mechanistically, GPA inhibited WSSV replication at least by reducing STAT expression to block the transcription of WSSV IE gene ie1. GPA also inhibited the expression of apoptosis related factor Bax inhibitor-1 which is beneficial for WSSV replication. In conclusion, GPA can be used as a potential agent to treat and prevent WSSV infection.