Coxsackie virus cannot be completely eliminated due to restrictive replication and impaired immune response, thus causing persistent infection. IL-10 plays a decisive role in the course of persistent viral infection. Umifenovir is a broad-spectrum antiviral drug, with certain treatment effects on Coxsackie virus infection. Previously, we showed that in addition to inhibiting Coxsackie B4 (CVB4) infection, Umifenovir also down-regulates IL-10 induced by persistent CVB4 virus infection in vitro and in vivo. Here, BALB/c mouse spleen cells infected with CVB4 were used as a model to explore the mechanism by which Umifenovir affects IL-10 expression. We found that subcellular localization of p38 and MAPK-activated protein kinase 2 (MK2) played a very important role in IL-10 secretion, and Umifenovir significantly prevented p38-MK2 complex from exiting the cell nucleus. This in turn blocked the biological functions of the latter pathway, and inhibited the high expression of IL-10 induced by CVB4. These findings suggest that Umifenovir is a potential anti-CVB4 drug; most importantly, Umifenovir could be used to treat IL-10 induced persistent viral infection.