Epidemiological Investigation and Genetic Evolution Analysis of Porcine Circovirus Type 3 of Chengdu in 2023
[Objective]The aim of this study was to investigate and analyse the prevalence and molecular genetic evolution of Porcine circovirus type 3(PCV3)in Chengdu area.[Method]A total of 2 113 dead pig tissue samples were collected from 4 harmless disposal sites in Chengdu area from January 2023 to December 2023,and the PCV3 infection was detected by Real-time quantitative PCR.Three pairs of primers were designed for PCR amplification and sequencing of PCV3 genome sequence of positive samples.Through online software splicing PCV3 genome sequence,intercepting ORF2 gene sequence and deducing Cap amino acid sequence,similarity comparison was carried out and genetic evolution tree was constructed.The mutation of Cap amino acid sequence was analyzed.[Result]The positive rate of PCV3 in 2 113 dead pig tissue samples was 27.21％(575/2 113).According to PCR amplification and sequencing results,the genome sequences of 15 PCV3 strains were obtained by splicing.The similarity analysis showed that the nucleotide sequences similarity among the 15 PCV3 genome was 97.2％-100％,the nucleotide sequences similarity among ORF2 genes was 97.2％-100％,and the amino acid sequences similarity among Cap sequences was 96.7％-100％.The results of genetic evolution tree showed that 12 PCV3 belonged to PCV3a subtype and 3 belonged to PCV3c subtype.A total of 13 of the 15 Cap amino acid sequences were mutated,and there were 13 mutation sites.[Conclusion]PCV3 in Chengdu area was mainly PCV3a and PCV3c subtypes with high genomic similarity and conservative sequences.The mutation sites of Cap amino acids were mainly concentrated in antigen epitope.The results suggested that scientific prevention and control policies should be formulated in this region to prevent the spread of the virus.
Porcine circovirus type 3(PCV3)epidemiologymolecular genetic evolution
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