The coagulation cascade and PAR1 and PAR2 enhance HSV infection of endothelial cells. TF is incorporated into the envelope of HSV after infection of TF⁺ cells. Upon binding to a target cell, TF in the envelope activates the coagulation cascade. In addition, the virally encoded glycoprotein C enhances activation of FX. The local generation of FXa and thrombin activate PAR1 and PAR2 on the cells, which increases infection, possibly by modifying receptors that mediate virus binding and entry. Professional illustration by Paulette Dennis.