An approach to a FMD vaccine based on genetic engineered attenuated pseudorabies virus: one experiment using VP1 gene alone generates an antibody responds on FMD and pseudorabies in swine.

Foot-and-mouth disease (FMD) and pseudorabies (PR) are two important infectious diseases in swine. An attenuated pseudorabies virus (PRV) has been successfully used as a gene delivery vector for the development of live-viral vaccines. In this study, a recombinant PRV-VP1 virus was constructed by fusioning the VP1 gene of FMD virus in frame to the N-terminal sequence of the gG gene of PRV. To test the protective immunity, 15 FMDV sero-negative white swine were divided into three groups and immunized with the recombinant PRV-VP1 virus, commercial FMD vaccine and vector virus (TK(-)/gG(-)/LacZ(+)), respectively, and challenged intramuscularly with 20 minimal infecting doses (MID) of virulent type O FMDV 4 weeks after booster immunization. Swine vaccinated with PRV-VP1 acquired antibodies against both FMDV and PRV, however, anti-FMDV antibodies were much lower than those vaccinated with the commercial FMD vaccine. Our results suggested that the recombinant PRV-VP1 virus, which only expressed FMDV VP1 gene controlled by PRV gG promoter, could not protect swine from the challenge of 20 MID type O FMDV, but could delay and reduce the clinical symptoms of FMD.