ROK or MLCK inhibition restricts Dengue virus replication in endothelial cells

Dengue virus (DV), a member of the Flaviviridae family, has been demonstrated to induce changes to the actin cytoskeleton to promote efficient viral entry and replication. These cytoskeletal alterations continue throughout infection, and disruption of the cytoskeleton has been shown to decrease the release of infectious virions. However, few studies have assessed the contribution of actin alterations to Dengue-induced vascular leak in endothelial cells. A number of cellular kinases control the assembly and rearrangement of actin filaments, including Rho-activated kinase (ROK) and Myosin Light Chain kinase (MLCK). To determine whether the observed changes to the actin cytoskeleton during Dengue viral infection contribute to the loss of endothelial cell barrier function, the roles of the cellular kinases ROK and MLCK were evaluated during DV infection. Inhibition of ROK and MLCK during infection prevented the formation of DV-induced actin stress fibers. While kinase inhibition did not prevent virus-induced changes in monolayer permeability, specific inhibition of either kinase resulted in a significant decrease in virus yield indicating that ROK/MLCK-mediated cytoskeletal alterations play a role in virus replication and biogenesis that do not affect vascular integrity in Dengue virus infection in vitro. Further investigation revealed that ROK or MLCK inhibition decreased virus spread through the culture, but only MLCK inhibition decreased viral protein synthesis and genome replication. Taken together, these results identify a critical role for both ROK and MLCK activity in the efficient replication of Dengue virus in endothelial cells, potentially affecting the assembly or budding of mature