Porcine Type I Interferon Rapidly Protects Swine Against Challenge with Multiple Serotypes of Foot-and-Mouth Disease Virus

Foot-and-mouth disease virus (FMDV) causes a highly contagious disease of cloven-hoofed animals. Current inactivated vaccines require approximately 7 days to induce protection, but before this time vaccinated animals remain susceptible to disease. Previously, we demonstrated that intramuscular (IM) inoculation of a replication-defective human adenovirus type 5 (Ad5) vector containing a porcine interferon alpha gene (pIFN alpha) can protect swine challenged 1 day later by intradermal (ID) injection with FMDV A24 Cruzeiro from both clinical disease and virus replication. To extend these studies to other FMDV serotypes, we demonstrated the effectiveness of Ad5-pIFN alpha against ID challenge with O1 Manisa and Asia-1 and against A24 Cruzeiro in a direct contact challenge model. We also showed that an Ad5 vector containing the pIFN beta gene can protect swine against ID challenge with A24 Cruzeiro. Further, IM inoculation of a 10-fold lower dose of Ad5-pIFN alpha at 4 sites in the neck compared with 1 site in the hind limb can protect swine against ID challenge. These studies demonstrate the ability of Ad5-delivered type I IFN to rapidly protect swine against several FMDV serotypes and suggest that various modifications of this approach may enable this strategy to be successfully used in other FMD susceptible species.