Emergence and etiological characteristics of novel genotype Ⅱ pseudorabies virus variant with high pathogenicity in Tianjin, China

• Published in: Microbial pathogenesis 2024-12, Vol.197, p.107061, Article 107061
• Main Authors: Cheng, Xue-jiao, Cheng, Ning, Yang, Cheng, Li, Xin-lei, Sun, Jiu-ying, Sun, Ying-Feng
• Format: Article
• Language: English
• Subjects: amino acids; Animals; Aujeszky disease; brain; Brain - pathology; Brain - virology; Cell Line; China; China - epidemiology; Disease Models, Animal; etiology; genes; Genetype; Genotype; Herpesvirus 1, Suid - classification; Herpesvirus 1, Suid - genetics; Herpesvirus 1, Suid - isolation & purification; Herpesvirus 1, Suid - pathogenicity; High pathogenicity; immunization; Mice; mortality; pathogenesis; pathogenicity; Phylogeny; Pseudorabies - epidemiology; Pseudorabies - virology; Pseudorabies virus; Suid alphaherpesvirus 1; Swine; Swine Diseases - virology; vaccines; Virulence - genetics; Virulence Factors - genetics; viruses
• ISSN: 0882-4010; 1096-1208; 1096-1208
• DOI: 10.1016/j.micpath.2024.107061

Pseudorabies (PR) is a highly infectious disease caused by pseudorabies virus (PRV). This study aimed to detect and identify recent outbreaks of genotype Ⅱ PRV, and further analysis it's etiological characteristics and pathogenicity. The brain tissues with suspected PRV infection were isolated and the main virulence-related genes of the isolated PRV strain were amplified and sequenced for phylogenetic analysis. In addition, the pathogenicity of the isolated PRV strain to 6-week-old mice and 9-days-old suckling piglets were evaluated. The results showed that a PRV strain was successfully isolated and named PRV TJbd2023 strain, which could proliferate in PK-15 cells and TCID50 of the 6th generation virus reached 107.57/0.1 ml. Phylogenetic trees and amino acids analysis were constructed based on full-length gE sequences, which showed that PRV TJbd2023 strain was clustered into genetype Ⅱ PRV variant with a characteristic 21-nucleotide insertion (encoding 63AASTPAA69) in gC gene, and some amino acid point mutations were also found in other virulence-related genes, including gB protein R223H and E836K, gD protein R320S, and gE protein T242A. Animal experiments showed that TJbd2023 could cause acute neurological symptoms with 103.41/mL LD50 on KM mice, and intranasal inoculation of suckling piglets with 2 ml of TJbd2023 strain(106.57/0.1 ml) led to a mortality rate of 66.70 %. Emerging genotype Ⅱ PRV variant such as isolated in our research named TJbd2023 with high pathogenicity might be responsible for recent outbreaks of PRV and immunization failure of Bartha-K61 vaccine in Tianjin, China. Emerging genotype Ⅱ PRV variant such as isolated in our research named TJbd2023 with high pathogenicity might be responsible for recent outbreaks of PRV and immunization failure of Bartha-K61 vaccine in Tianjin, China. [Display omitted] •The main virulence-related genes characterization of a PRV (TJbd2023) variant was analyzed.•TJbd2023 was shown to genotype Ⅱ PRV variant with a characteristic 21-nucleotide insertion (encoding 63AASTPAA69) in gC gene.•The isolate TJbd2023 shared high virulence for mice and piglets.