A Bicistronic DNA Vaccine Containing Gene of FMDV and Bovine IFN-α Can Prime Humoral and Cellular Immune Responses of Guinea Pigs

The study was conducted to evaluate the immunogenicity and protective efficacy of a DNA vaccine against foot-and-mouth disease virus (FMDV). Genes encoding the P1, 2A, 3C of FMDV O/China99 and bovine IFN-α were cloned into pcDNA3.1 (+) expression vector under CMV promoter and FMDV IRES control, respectively. The recombinant plasmids were administered to guinea pigs by intramuscular injection with monoor bicistronic expression plasmids and aurintricarboxylic acid (ATA). After 2 sequential vaccinations with plasmid DNA, all of guinea pigs were challenged with 100 ID50 FMDV O/China99. Anti-FMDV antibodies were detected by ELISA and neutralization assay, and the phenotyping of T-cell subpopulation in the peripheral blood were performed by flow cytometry. Vaccination of guinea pigs with monoor bicistronic expression plasmids induced humoral and cellular immune responses to FMDV antigens. In the challenge test, a part of the animals were protected against the challenge of a virulent virus. This study demonstrates that the delivery of FMDV antigens via bicistronic vectors is feasible. Further experimentation with bicistronic delivery systems is required for the optimization and refinement of DNA vaccines to effectively prime protective immune responses against foot-and-mouth disease (FMD).