Because Ad5 lacking E1A and E1B had been used for delivery of RNAi by several groups [6, 40, 48] , we evaluated the antiviral potential of combination inoculations of rS. cho and rAd5 in guinea pigs. The results indicate that no significant increase in antiviral effect was achieved in the group treated with the p3D-NT56/S. cho+Ad5-POL mixture, as compared to the group treated with p3D-NT56/S. cho alone. Kim et al. [25] attempted to improve the antiviral effect by use of a mixture of two adenovirus constructs, by giving two injections of shRNA prior to FMDV challenge and by giving injections after FMDV challenge. The high survival rate was maintained by treatment with adenoviruses post-challenge. These results could encourage us to seek more efficient methods of treatment.