Pseudorabies virus glycoprotein B can be used to carry foot and mouth disease antigens in DNA vaccination of pigs

To evaluate the feasibility of using pseudorabies virus (PrV) glycoprotein B (gB) as a carrier of foot and mouth disease virus (FMDV) antigens in DNA immunization, FMDV B- and T-cell epitopes were inserted either between the two B-cell epitopes of the N-term subunit of PrV-gB (BT-PrV-gB–N-term construct) or within the B-cell epitope of the C-term subunit of PrV-gB (BT-PrV-gB–C-term construct). Two animal experiments were performed, each with three injections of plasmids 2 weeks apart, followed by a booster inoculation of peptides corresponding to the FMDV epitopes. Control groups of pigs were injected with plasmids encoding either PrV-gB or FMDV-BT, or with empty-pcDNA3. The results of both assays were combined. Significant titers of FMDV neutralizing antibodies were detected after the peptides boost in groups injected with the BT-PrV-gB–C-term construct. Insignificant amounts were detected in groups injected with the BT-PrV-gB–N-term and FMDV-BT constructs. PBMCs from the BT-PrV-gB–N-term groups, isolated after the peptide boost injection, produced IFN-γ and IL-4 mRNAs in vitro when stimulated with FMDV peptides. This was not observed with the other groups. These results imply that PrV-gB can be used to carry FMDV antigens in a DNA vaccine.