Evaluation of Immunogenicity of Gene-Deleted Vaccine and Subunit Vaccine Constructed Against the Emerging Variant Pseudorabies Virus

Pseudorabies (PR) is an important infectious disease affecting pig farms worldwide. Since 2011, the emergence of variant strains of pseudorabies virus (PRV) had led to outbreak of PR in many vaccinated pig farms of China. Therefore, there is an urgent need to develop new vaccines against variant strains. In this study, based on the highly virulent PRV SD2017 mutant strain, the gene deleted strains SD2017ΔgE/gI and SD2017ΔgE/gI/TK-EGFP were constructed using homologous recombination technology. Using DC cell targeting peptide (DCpep) as an intramolecular adjuvant, and the outer membrane protein PorB of Neisseria meningitidis as a new protein adjuvant, PRV gB-DCpep and PorB protein containing gp67 protein secretion signal peptide were expressed using the baculovirus system. Rabbits that were intramuscularly vaccinated with PRV SD2017ΔgE/gI/TK live attenuated vaccine, PRV-gB+PorB subunit vaccine, and SD2017ΔgE/gI+PorB inactivated vaccine showed significantly higher PRV-specific antibodies, neutralizing antibodies, and intracellular cytokines. Through histopathological examination, it was found that no obvious histopathological damage was observed in the vaccinated rabbits. In addition, compared with the live attenuated vaccine, the PRV-gB+PorB subunit vaccine was effective against PRV infection. In general, the above three new vaccines were potential candidates for the development of PRV variant vaccines.