Technical Abstract: The biting gnat, Culicoides sonorensis, is a potential biological vector for the transmission of vesicular stomatitis virus (VSV) in the western United States. When a virus-infected insect bites a susceptible host, numerous salivary proteins and virus are delivered to the tissues. In general, these salivary proteins facilitate feeding and inhibit host immune responses. To determine what effect Culicoides salivary gland proteins may have on VSV infection in horses, equine dermal cells were treated with salivary gland homogenates (SGH) simultaneously with, or prior to, infection with VSV. Treatment of cells with SGH resulted in a dose dependent increase in VSV infection. This viral potentiation likely facilitates the establishment of a localized infection from the minute inoculum at the site of the bite.