Recombinant pseudorabies virus expressing the consensus VP2 protein of porcine parvovirus 1 (PPV1) protects pigs against pseudorabies virus and PPV1.

Abstract

Pseudorabies virus (PRV) and porcine parvovirus type 1 (PPV1) are major pathogens that cause reproductive disorders in sows, and mixed infections are frequently detected on pig farms. In this study, a recombinant PRV (rPRV-VP2) based on a PRV variant (HLJ8) was constructed to express the PPV1 VP2 protein. To ensure safety, four virulence genes (TK, gE, gI, and UL39) of PRV HLJ8 were deleted, followed by further evaluation of safety and immunogenicity in piglets. The PPV1 VP2 expression cassette was inserted into the gE/gI deletion site, enabling successful expression of the VP2 protein, which exhibited hemagglutination activity with a titre of 1:64. Animal experiments demonstrated that rPRV-VP2 elicited robust antibody responses against both PRV and PPV1, providing complete protection in both mice and piglets. Compared with commercial PRV and PPV1 vaccines, rPRV-VP2 conferred comparable or superior protection, resulting in not only no clinical symptoms but also significantly reduced viral loads in tissues. The deletion of the gE gene can distinguish wild-type virus infection from vaccine immunity in clinical applications. Overall, rPRV-VP2 offers a safe and effective strategy for dual protection against PRV and PPV1, reducing vaccination costs in pig production.