Pharmacological elevation of cellular dihydrosphingomyelin provides a novel antiviral strategy against West Nile virus infection

Flavivirus life cycle is strictly dependent on cellular lipid metabolism. Polyphenols like gallic acid and its derivatives are promising lead compounds for new therapeutic agents as they can exert multiple pharmacological activities, including the alteration of lipid metabolism. The evaluation of our own collection of polyphenols against West Nile virus, a representative medically relevant flavivirus, led to the identification of N,N'-(dodecane-1,12-diyl)bis(3,4,5-trihydroxybenzamide) and its 2,3,4-trihydroxybenzamide regioisomer as selective antivirals with low cytotoxicity and high antiviral activity (EC50 of 2.2 and 0.24 M, respectively in Vero cells; EC50 of 2.2 and 1.9 M, respectively in SH-SY5Y cells). These polyphenols also inhibited the multiplication of other flaviviruses, namely Usutu, dengue, and Zika viruses, exhibiting lower antiviral or negligible antiviral activity against other RNA viruses. The mechanism underlying their antiviral activity against WNV involved the alteration of sphingolipid metabolism. These compounds inhibited ceramide desaturase (Des1) promoting the accumulation of dihydrosphingomyelin (dhSM), a minor component of cellular sphingolipids with important roles on membrane properties. Addition of exogenous dhSM, or Des1 blockage by using the reference inhibitor GT-11, confirmed the involvement of this pathway in WNV infection. These results unveil the potential of novel antiviral strategies based on the modulation of the cellular levels of dhSM and Des1 activity for the control of flavivirus infection.