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Molecular epidemiology and biological characteristics of swine pseudorabies virus in Henan province of China during 2012 to 2019
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  • Huihua Zheng,
  • Yi-Lin Bai,
  • Yu Zhang,
  • Yu Zhao,
  • Lan-Lan Zheng,
  • Fang Liu,
  • Hongying Chen
Huihua Zheng
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Yi-Lin Bai
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Lan-Lan Zheng
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Hongying Chen
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Abstract

Since late 2011, pseudorabies virus (PRV; Suid herpesvirus 1) infection was widely prevalent in vaccinated swine farms in China, and caused tremendous economic losses in the swine industry. To understand the epidemic and biological characteristics of the virus, a total of 1,174 tissue samples were collected from Bartha-K61-immunized swine farms in Henan province of China between 2012 and 2019, and PRV strains were isolated and the complete sequences of gE and gC genes were amplified by PCR. The detection rate of PRV was 15.25% (179/1174), which varied from 6.61% to 25.00% between 2012 and 2019. And 16 PRV isolates were obtained, and could cause clinical symptoms and death in mice. The phylogenetic trees based on the sequences of gE and gC genes showed that the 16 PRV strains in this study at these two phylogenetic trees all clustered to a relatively independent branch altogether with the Chinese variant PRV strains (after 2012), and sequence analysis of the isolates revealed that gE and gC both contained amino acid insertions, substitutions or deletions compared with European-American PRV strains and early Chinese PRV strains (before 2012). In addition, it was the first report that eight strains (8/16) in this study harbored a unique amino acid substitution at site 280 (F to L) of gC gene. In the protection assay, the emulsion containing inactivated PRV NY isolate could provide complete protection against variant NY, and the titer of neutralizing antibodies was 1:82. This study might enrich our understanding of the evolution of variant PRVs as well as pave the way for finding a model virus to develop a novel vaccine based on PRV variants.