Pathogenicity and immunogenicity of a quadruple gene-deleted pseudorabies virus variant as a vaccine candidate

Since late 2011, the PRV variants have emerged in China, characterized by the increased virulence. The traditional attenuated vaccines have proven insufficient in providing complete protection, resulting in substantial economic losses to swine industry. In this study, a vaccine candidate strain, ZJ01-ΔgI/gE/TK/UL21, carrying the quadruple gene deletion was derived from the previously generated three gene-deleted virus ZJ01-ΔgI/gE/TK. As anticipated, piglets inoculated with ZJ01-ΔgI/gE/TK/UL21 exhibited normal body temperatures and showed no viral shedding, consistent with the observations from piglets treated with ZJ01-ΔgI/gE/TK. Importantly, a significant higher level of interferon induction was observed among piglets in the ZJ01-ΔgI/gE/TK/UL21 group compared to those in the ZJ01-ΔgI/gE/TK group. Upon challenge with the PRV variant ZJ01, piglets immunized with ZJ01-ΔgI/gE/TK/UL21 exhibited reduced viral shedding compared to the ZJ01-ΔgI/gE/TK group. Furthermore, piglets vaccinated with ZJ01-ΔgI/gE/TK/UL21 exhibited minimal pathological lesions in brain tissues, similar to those in the ZJ01-ΔgI/gE/TK group. These results underscore the potential of ZJ01-ΔgI/gE/TK/UL21 as a promising vaccine for controlling PRV infection.