Suppression of Calcium Influx Reduces Coxsackievirus B3 Lethality With Elevated Interferon Beta Responses in Mice

The disease course of severe enterovirus (EV) infection with hepatic necrosis is usually fulminant and fatal. Coxsackievirus (CVB3) is the emerging and important serotype of newborn EV inducing hepatic necrosis. Calcium (Ca²⁺) regulates host immunity, type I interferon (IFN-I), and viral infections. The interaction of Ca²⁺, IFN-I, and CVB3-induced hepatitis remains to be investigated. To address these issues, we used the Ca²⁺ blocker manidipine, which reduces Ca²⁺ influx into cells and is used in the clinic, the human hepatoma cell line (HuH7) for in vitro studies, and a murine infection model. In vitro results showed that CVB3 infection increased levels of intracellular Ca²⁺ and Ca²⁺-binding proteins, calmodulin and calcineurin, which are IFN-I suppressors. Moreover, manidipine decreased CVB3 titers in a manner dependent on IFN-I. Mouse results revealed that manidipine reduced CVB3 lethality, viral loads, and organ damage of infected mice with elevated levels of IFN-β protein and mRNAs encoding IFN-β and interferon-stimulated genes (ISGs), especially in the liver. Mechanism studies showed that manidipine enhanced the levels of mRNAs encoding IFN-β or ISG, IFNB1 promoter activity, and IFN-β induction pathways of both RLR and STING in infected HuH7 cells. Overall, CVB3 infection increases Ca²⁺ influx to suppress IFN-β, and blocking Ca²⁺ influx has the potential to reduce CVB3 infection by enhancing IFN-β.