Variations in glycoprotein B contribute to immunogenic difference between PRV variant JS-2012 and Bartha-K61

• Published in: Veterinary microbiology Vol. 208; pp. 97 - 105
• Main Authors: Yu, Zhi-qing, Tong, Wu, Zheng, Hao, Li, Li-wei, Li, Guo-xin, Gao, Fei, Wang, Tao, Liang, Chao, Ye, Chao, Wu, Ji-qiang, Huang, Qinfeng, Tong, Guang-zhi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2017; Elsevier BV
• Subjects: Animals; Antibodies, Neutralizing; Antigenic variation; Cell Line; Combined vaccines; CRISPR; Farms; Gene Expression Regulation, Viral; Genetic Variation; Glycoprotein B; Glycoproteins - genetics; Growth kinetics; Herpesvirus 1, Suid - genetics; Herpesvirus 1, Suid - immunology; Homologous recombination; Homology; Immunization; Immunogenicity; Kinetics; Livestock; Mice; Pathogenicity; Pathogens; Pseudorabies - immunology; Pseudorabies - mortality; Pseudorabies - virology; Pseudorabies virus variant; Rodents; Studies; Swine; Swine Diseases - immunology; Swine Diseases - virology; Swine houses; Vaccines; Variation; Virulence; Viruses; China; Glycoprotein B; Antigenic variation; Pseudorabies virus variant
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2017.07.019

•gB-exchange between Bartha-K61 and JS-2012-ΔgE/gI significantly affect protective efficacy of both viruses.•Variations in gB gene plays a critical role in emerging PRV variant prevailing in Bartha-K61 vaccinated pig farms.•Recombinant BJB based on Bartha-K61 with gB from PRV variant could be a promising vaccine candidate for future control of variant PRV. A newly emerged pseudorabies virus (PRV) variant has been identified in many Bartha-K61-vaccinated pig farms. This variant has caused great economic losses to the swine industry in China since 2011. Sequence analysis demonstrated that the gB gene of the emerging PRV variant JS-2012 had multiple variations compared with the vaccine strain Bartha-K61. In the study, a specific CRISPR/Cas9 system combined with homologous recombination was used to construct two recombinant viruses, BJB (Bartha-K61+JS-2012gB) and JBJ (JS-2012-ΔgE/gI+Bartha-K61gB), by interchanging the full-length gB genes between Bartha-K61 and JS-2012-ΔgE/gI. The two recombinant viruses showed similar characteristics in growth kinetics in vitro and similar pathogenicity in mice, as compared to their parental strains. Immunization of mice with inactivated BJB or JBJ followed by challenge of JS-2012 showed that BJB could increase protective efficacy to 80%, compared to only 40% protection by the parental Bartha-K61 strain. JBJ had a decreased protective efficacy of 65%, as compared to 90% protection by its parental JS-2012-ΔgE/gI strain. Exchange of the gB gene markedly altered the immunogenicity of the recombinant PRV. These data suggest that variations in gB might play an important role in the virulence of the reemergent PRV variant in China. Our results demonstrate the importance of gB in protective immunity and suggest that the recombinant virus BJB could be a promising vaccine candidate for eradication of the PRV variant.