Isolation And Identification Of The Shanxi Strain Of Porcine Pseudorabies Virus Genetic Variation Analysis

To investigate the prevalence of pseudorabies and genetic variation of pseudorabies virus in Shanxi Province.PRV serological and pathogenic were tested by the ELISA and q PCR on large-scale pig farms from parts of Shanxi Province in 2018-2020.The positive disease material was inoculated on Vero cells to isolate PRV,then the genetic variation and biological characteristics of the isolated PRV were analyzed.The results showed that from 2018 to 2020,the average g B antibody positive rate of the pig herd showed an overall upward trend,from less than 80% to more than 97%.The average g E antibody positive rate showed a trend of first increasing and then decreasing,and pigs with g E antibody positive rate has increased year by year,but the overall pathogen detection rate decreased from 15.99% to 0.22% from 2018 to 2020,and the pathogen detection rate decreased year by year;from 2019 to 2020,two PRV strains were isolated and named SX1911 and SX2020.SX1801 and SX1802 strains are isolated strains in the early stage in the laboratory.The genetic variation of g C and g E genes based on isolated were analysed.The g C nucleotide and amino acid of the four strains showed 94.9%-100% and 90.4%-100% identity compared to the PRV strains from China,European and American respectively.And g E nucleotide and amino acid homology of the three isolated strains are 97.9%-100% and 95.7%-100% in comperared with reference strains.In addition,g C amino acid sequences of the 3 isolates contained 7 continuous residues insertions,AAASTPA were inserted at positions 63-69;and two aspartate amino acid insertions were observed at position 48 and497 in the g E.Phylogenetic analysis showed that the four isolated strains are the same as virus isolated since 2011,which belong to the variant strains.Four PRV variant isolates were purified by plaque purification and methylcellulose fixation and stained with crystal violet.It was found that the plaques of SX1801 and SX1911 were significantly smaller than those of SX1802 and SX2020.After measuring the multi-step growth curve of the virus,the results showed that the virus titers measured by the four PRV isolates at different time points were not significantly different.The pathogenicity of the four PRV isolates from high to low was SX1802,SX2020,and SX1801,SX1911,the results show that different strains of PRV have different biological characteristics.Overall,our research can provide a theoretical basis for the PRV epidemic situation and prevention and control of the disease in Shanxi Province.