Molecular Epidemiological Investigation Of Porcine Circovirus 2 In Liaoning Province

This test is intended to epidemiological investigation and select highly homologous strain to inactivated vaccine for porcine circovirus type 2 in Liaoning Province. Use ELISA to serological surveys PCV2 in Liaoning Province 14 prefecture-level cities and 16 county area representative of conducted in 2014～2015.Collection the pigs suspected post weaning multisystemic wasting syndrome (PMWS) in Liaoning province, are detected to PCV2 by PCR method. Find 20 positive samples are cloned and sequenced analysis the whole genome.The PCV2 serological survey found that, immunity herd has good effect, unimmunized herds PCV2 seroprevalence increased year by year. Unvaccinated herds antibody positive rate are differences in different regions and in different stages of growth, unvaccinated herds the highest infection rate in winter and summer.The PCV2 etiological survey found that, PCV2 mortality high, and incidence of each region has increased significantly. Winter is the highest incidence, especially on November nearly 80%. Different with serological finding, piglets’serological antibody was 73%, but positive rate only 13.81%.The reason is non-immunized piglets antibodies are obtained from the sow, thus reduce the incidence.The result of genomic sequence analysis shows that,18 strains are 1767 bp and 2 strain are 1768 bp. The nucleotide homology is 94.4%-99.9%. In the phylogenetic tree, Liaoning Province is most popular PCV2b type, in western and northern mainly popular PCV2b genotype 1A/1B subtype. The amino acid homology of ORF2 is 89.6% to 100%, there are 40 mutation points.16 stains are virulent and 4 weak.19 strains of glycosylation sites conserved NYS, SYC9 strain mutation YYS.16 viral strains’ Polar basic amino acids K becomes positively charged polar amino acids N uncharged. This 20 PCV2 ORF2 Liaoning strain localization in two pairs play a key role in the 12-18 aa and 34-41 aa very conservative.