Serological Investigation and Genetic Characteristics of Pseudorabies Virus between 2019 and 2021 in Henan Province of China

Abstract

In late 2011, severe pseudorabies (PR) outbreaks occurred among swine herds vaccinated with the Bartha-K61 vaccine in many provinces of China, causing enormous economic losses for the pork industry. To understand the epidemic profile and genetic characteristics of the pseudorabies virus (PRV), a total of 35,796 serum samples were collected from 1090 pig farms of different breeding scales between 2019 and 2021 in the Henan province where swine had been immunized with the Bartha-K61 vaccine, and PRV glycoprotein E (gE)-specific antibodies were detected using an enzyme-linked immunosorbent assay (ELISA). The results reveal that the overall positive rate for PRV gE antibodies was 20.33% (7276/35,796), which decreased from 25.00% (2596/10,385) in 2019 to 16.69% (2222/13,315) in 2021, demonstrating that PR still existed widely in pig herds in the Henan province but displayed a decreasing trend. Further analysis suggested that the PRV-seropositive rate may be associated with farm size, farm category, quarter, region and the cross-regional transportation of livestock. Moreover, the gE gene complete sequences of 18 PRV isolates were obtained, and they shared a high identity (97.1–100.0%) with reference strains at the nucleotide level. Interestingly, the phylogenetic analysis based on the gE complete sequences found that there were both classical strains and variant strains in pig herds. The deduced amino acid sequence analysis of the gE gene showed that there were unique amino acids in the classical strains, the variant strains and genotype Ⅱ strains. This study provides epidemiological data that could be useful in the prevention of pseudorabies in Henan, China, and this finding contributed to our understanding of the epidemiology and evolution of PRV.

Simultaneous Detection of Porcine Respiratory Coronavirus, Porcine Reproductive and Respiratory Syndrome Virus, Swine Influenza Virus, and Pseudorabies Virus via Quadruplex One-Step RT-qPCR

“…From 2012 to 2017, the PRV strains circulating in China showed a significantly different evolutionary relationship compared to those in other countries [ 42 ]. From 2017 to 2021, varying degrees of PRV infections were found at pig farms in several provinces in China, with the presence of classical strains, variant strains, and recombinant strains [ 43 , 44 , 45 ]. These results demonstrated that existing commercial vaccines could not prevent the emergence of new strains of PRV.…”

Isolation and Characterization of Yunnan Variants of the Pseudorabies Virus and Their Pathogenicity in Rats

“…Developed countries, such as the United States, utilize the gE gene deletion vaccine and accompanying diagnostic methods to control and eradicate PRV infections. However, PRV infections remain prevalent in swine herds with sporadic epidemics in many countries, including China [ 16 , 17 ]. In this study, the average positivity rate of PRV-gE was 29.6%.…”

Epidemiological Investigation, Risk Factors, Spatial-Temporal Cluster, and Epidemic Trend Analysis of Pseudorabies Virus Seroprevalence in China (2017 to 2021)

“…Similarly, Liu et al found a decreased positive rate of PRV gE antibody from 2013 to 2016 (22.17% to 13.14%) ( 18 ). Chen et al analyzed 35,796 serum samples collected in Henan province from 2019 to 2021 and observed that the positivity rate of PRV gE antibody dropped from 25% to 16.69% ( 23 ). These epidemiological findings are consistent with our model results.…”