Curcumin inhibits Singapore grouper iridovirus infection through multiple antiviral mechanisms

Singapore grouper iridovirus (SGIV) is one of the main pathogens that causes high mortality and substantial economic losses in the grouper aquaculture industry. Curcumin is a polyphenolic compound extracted from the traditional Chinese medicinal material, turmeric. In this study, we investigated the antiviral properties of curcumin against SGIV based on quantitative real-time PCR (qRT-PCR), western blotting, and viral titer assessment with in vitro models, and found that different concentrations of curcumin inhibited SGIV infection. Furthermore, curcumin significantly impaired attachment of the virion. Moreover, the qRT-PCR results showed that cellular immune and inflammatory responses related to the NF-κB signaling pathway were regulated by curcumin. Examinations of the expression of antioxidant enzymes indicated that the antioxidant capacity played a critical role in preventing SGIV infection, which may depend on the Nrf2/Keap1 signaling pathway. Importantly, curcumin also had a strong antiviral activity in vivo according to the increased survival rates of groupers and inhibition of SGIV gene expression. This study demonstrated that curcumin could inhibit SGIV infection both in vitro through multiple antiviral mechanisms and reduce the mortality of SGIV-infected groupers in vivo. Overall, our findings show that SGIV is sensitive to curcumin and its antiviral activity makes it a potential candidate drug for treating SGIV infection.