Hesperetin protects crayfish Procambarus clarkii against white spot syndrome virus infection.

Hesperetin is a natural flavanone compound, which mainly exists in lemons and oranges, and has potential antiviral and anticancer activities. In this study, hesperetin was used in a crayfish pathogen challenge to discover its effects on the innate immune system of invertebrates. The crayfish Procambarus clarkii was used as an experimental model and challenged with white spot syndrome virus (WSSV). Pathogen challenge experiments showed that hesperetin treatment significantly reduced the mortality caused by WSSV infection, while the VP28 copies of WSSV were also reduced. Quantitative reverse transcriptase polymerase chain reaction revealed that hesperetin increased the expression of several innate immune-related genes, including NF-kappaB and C-type lectin. Further analysis showed that hesperetin treatment plays a positive effects on three immune parameters like total hemocyte count, phenoloxidase and superoxide dismutase activity. Nevertheless, whether or not infected with WSSV, hesperetin treatment would significantly increase the hemocyte apoptosis rates in crayfish. These results indicated that hesperetin could regulate the innate immunity of crayfish, and delaying and reducing the mortality after WSSV challenge. Therefore, the present study provided novel insights into the potential therapeutic or preventive functions associated with hesperetin to regulate crayfish immunity and protect crayfish against WSSV infection, provide certain theoretical basis for production practice.