Molecular epidemiology and biological characteristics of swine
pseudorabies virus in Henan province of China during 2012 to 2019
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.