Molecular epidemiological analysis of porcine circovirus type 2 in Zhejiang Province from 2016 to 2020
In order to investigate the molecular epidemiology and genetic variation of porcine circovirus type 2 (PCV2) in Zhejiang Province, a total of 1 725 clinical samples suspected of PCV2 infection were collected from different regions of Zhejiang Province between 2016 and 2020. All these samples were su...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Zhejiang University Press
2022-10-01
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| Series: | 浙江大学学报. 农业与生命科学版 |
| Subjects: | |
| Online Access: | https://www.academax.com/doi/10.3785/j.issn.1008-9209.2021.11.051 |
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| Summary: | In order to investigate the molecular epidemiology and genetic variation of porcine circovirus type 2 (PCV2) in Zhejiang Province, a total of 1 725 clinical samples suspected of PCV2 infection were collected from different regions of Zhejiang Province between 2016 and 2020. All these samples were subjected to pathogenic detection by polymerase chain reaction (PCR). The whole genomes of some positive samples were amplified, cloned and sequenced, and compared with sequences of 16 reference strains in the GenBank for genetic evolution analysis. The results showed that 359 samples were tested positive, with an average positive rate of 20.8%, and the positive rates from 2016 to 2020 were 38.1%, 23.2%, 24.1%, 12.5%, and 10.7%, respectively. The whole genomes of 36 isolates were sequenced. Multiple sequence alignments showed that the nucleotide sequence homologies among 36 PCV2 strains were 94.0%-99.9%, while the homologies were up to 94.7%-98.5% compared with the domestic vaccine strains, and 92.9%-99.8% compared with the reference strains. The phylogenetic analysis showed that these 36 isolates belong to three genotypes, including 11 strains of PCV2a genotype, eight strains of PCV2b genotype and 17 strains of PCV2d genotype. Among these, PCV2d was the predominant genotype. The length of PCV2 ORF2 gene was 705 bp in 16 isolates and 702 bp in 20 isolates. The nucleotide sequence homologies of ORF2 gene among these 36 isolates were 88.7%-100.0%, while the homologies were 90.2%-99.6% compared with the domestic vaccine strains, and 85.0%-100.0% compared with the reference strains. The amino acid sequence analysis of Cap protein indicated a large number of point mutations in addition to the only highly conserved glycosylation site. Moreover, different genotypes had characteristic mutation sites, and the specific mutation sites of dominant genotype PCV2d were mainly concentrated in I<sup>53</sup>, N<sup>68</sup>, L<sup>89</sup>, T<sup>121</sup>, R<sup>168</sup>, and I<sup>215</sup>. This study provides a reference for the immune prevention of PCV2 in Zhejiang Province and accumulates effective materials for the development of new vaccines. |
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| ISSN: | 1008-9209 2097-5155 |