A novel inactivated gE/gI deleted pseudorabies virus (PRV) vaccine completely protects pigs from an emerged variant PRV challenge

•PRV ZJ01 BAC clone was constructed by homologous recombination in lieu of Us7 (gI) and Us8 (gE).•Inactivated vZJ01ΔgE/gI vaccine other than Bartha-K61 can provide full protection against the lethal ZJ01 challenge.•Inactivated vZJ01ΔgE/gI vaccine generated high levels of NT antibodies against ZJ01 and Bartha-K61 vaccine strains.

A highly virulent and antigenic variant of pseudorabies virus (PRV) broke out in China at the end of 2011 and caused great economic loss in the pig industry. In this study, an infectious bacterial artificial chromosome (BAC) clone containing the full-length genome of the emerged variant PRV ZJ01 strain was generated. The BAC-derived viruses, vZJ01-GFPΔgE/gI (gE/gI deleted strain, and exhibiting green autofluorescence), vZJ01ΔgE/gI (gE/gI deleted strain), and vZJ01gE/gI-R (gE/gI revertant strain), showed similar in vitro growth to their parent strain. In pigs, inactivated vZJ01ΔgE/gI vaccine generated significantly high levels of neutralizing antibodies against ZJ01 compared with Bartha-K61 live vaccine (p < 0.05). After fatal ZJ01 challenge, all five animals in the inactivated vZJ01ΔgE/gI vaccine group survived without exhibiting any clinical sings, but two of five animals exhibited central nervous signs in the Bartha-K61 group. Meanwhile, all the non-vaccinated control animals died at 7 days post-challenge. This indicates that the inactivated vZJ01ΔgE/gI vaccine is a promising vaccine candidate for controlling the variant strains of PRV now circulating in China.