Immunogenicity of recombinant BCGs expressing predicted antigenic epitopes of bovine viral diarrhea virus E2 gene

• A vaccine to prevent tuberculosis and bovine viral diarrhea (BVD) was constructed.
• Antigenic epitopes were predicted in the BVD virus (BVDV) E2 gene.
• Six BVDV E2-derived antigens were expressed in Bacillus Calmette–Guerin (BCG).
• All recombinant BCG (rBCG) strains enhanced humoral and cellular responses in mice.
• rBCG expressing E2 with a 45 aa N-terminal deletion was most immunogenic.

To develop a vaccine to prevent diseases caused by Mycobacterium tuberculosis and bovine viral diarrhea virus (BVDV) simultaneously, recombinant Bacillus Calmette–Guerin (rBCG) vaccines expressing different regions of the BVDV E2 gene were constructed. Using DNASTAR 6.0 software, potential antigenic epitopes were predicted, and six regions were chosen to generate recombinant plasmids with the pMV361 vector (pMV361-E2-1, pMV361-E2-2, pMV361-E2-3, pMV361-E2-4, pMV361-E2-5 and pMV361-E2-6, respectively). The recombinant plasmids were transformed into BCG, and protein expression was thermally induced at 45 °C. Mice were immunized with 5 × 106 CFU/200 µL of each rBCG strain. Compared with other groups, BVDV E2 specific antibody titers were higher in mice immunized with rBCG-E2-6. Ratios and numbers of CD4+, CD8+ and IL-12 expressing spleen lymphocytes of the rBCG-E2-6 group also were higher than those of other groups. Thus, the rBCG-E2-6 vaccine showed the highest immunogenicity of all groups based on the humoral and cellular responses to vaccination.