The Construction and Immunogenicity Analyses of a Recombinant Pseudorabies Virus with Senecavirus A VP2 Protein Coexpression

Senecavirus A (SVA)-associated porcine idiopathic vesicular disease (PIVD) and pseudorabies (PR) are highly contagious swine diseases that pose a significant threat to the swine industry in China. Since there is currently no effective commercial vaccine against SVA, the virus has spread widely throughout China and its pathogenicity has increased over the last decade. In this study, a recombinant strain named rPRV-XJ-ΔTK/gE/gI-VP2 was constructed by using the pseudorabies virus (PRV) variant strain XJ as the parental virus and by deleting the TK/gE/gI gene while coexpressing SVA VP2. The recombinant strain can stably proliferate and express foreign protein VP2 in BHK-21 cells while having a similar virion appearance to that of the parental strain. rPRV-XJ-ΔTK/gE/gI-VP2 is safe and effective for BALB/c mice, inducing high levels of neutralizing antibodies against both PRV and SVA, providing 100% protection from the virulent PRV strain. Histopathological examination and quantitative PCR (qPCR) assay have demonstrated that SVA can infect mice through intranasal inoculation, while the vaccination of mice with rPRV-XJ-ΔTK/gE/gI-VP2 can significantly reduce SVA virus copies and alleviate the pathological inflammatory changes in the heart and liver. The evaluation of the safety and immunogenicity indicates that rPRV-XJ-ΔTK/gE/gI-VP2 holds promise as a candidate vaccine against PRV and SVA. IMPORTANCE This study reports the construction of a recombinant PRV with SVA for the first time, and the resulting virus, rPRV-XJ-ΔTK/gE/gI-VP2, can induce high levels of neutralizing antibodies against both PRV and SVA in model mice. These findings provide valuable insights for evaluating the effectiveness of rPRV-XJ-ΔTK/gE/gI-VP2 as a vaccine for pigs. Additionally, this study reports transient SVA infection in mice, with qPCR assays showing that the copies of the SVA 3D gene peaked at 3 to 6 days postinfection and fell below the sensitivity threshold by 14 days postinfection. The copies of the gene were more regular and at a higher level in the heart, liver, spleen, and lung tissue.