Construction and Immunogenicity of a Recombinant Pseudorabies Virus Expressing the Major Neutralizing Epitopes A and D of Transmissible Gastroenteritis Virus Spike Protein.

Transmissible gastroenteritis (TGE) and pseudorabies (PR) remain important viral diseases causing massive economic losses and posing a continuous burden on the global swine industry. The continuous emergence of variant strains of transmissible gastroenteritis virus (TGEV) and pseudorabies virus (PRV) has gradually weakened the protective efficacy of traditional vaccines, highlighting the urgent need for next-generation preventive vaccine candidates. Here, we constructed a recombinant pseudorabies virus named rPRV-AD expressing the major neutralizing epitopes A and D of the TGEV spike protein via homologous recombination combined with CRISPR/Cas9-gene editing technology and then evaluated its biological characteristics in vitro and immunogenicity in piglets. The results showed that this recombinant virus exhibited similar replication kinetics and biological properties to the parental strain. Immunization of 2-week-old piglets with rPRV-AD caused no obvious adverse effects and induced specific antibody and neutralizing antibody responses against both TGEV and PRV. Following virulent TGEV challenge, compared with the DMEM control group, rPRV-AD immunization alleviated clinical signs of piglets and significantly reduced viral load in intestine and feces, although its protective efficacy was lower than that of the commercial TGEV vaccine. Moreover, rPRV-AD provided effective clinical protection against challenge with the virulent PRV NY strain. In summary, these findings suggest that rPRV-AD represents a vaccine candidate that provides partial protection and warrants further optimization, and yet shows short-term protective efficacy against both PRV and TGEV in pigs.