First molecular detection and genetic analysis of porcine circovirus 4 in the Southwest of China during 2021-2022

Tong Xu; Dong You; Fang Wu; Ling Zhu; Xian-Gang Sun; Si-Yuan Lai; Yan-Ru Ai; Yuan-Cheng Zhou; Zhi-Wen Xu

doi:10.3389/fmicb.2022.1052533

First molecular detection and genetic analysis of porcine circovirus 4 in the Southwest of China during 2021-2022

Front Microbiol. 2022 Nov 3:13:1052533. doi: 10.3389/fmicb.2022.1052533. eCollection 2022.

Authors

Tong Xu¹, Dong You¹, Fang Wu¹, Ling Zhu^{1

2}, Xian-Gang Sun¹, Si-Yuan Lai¹, Yan-Ru Ai¹, Yuan-Cheng Zhou^{3

4}, Zhi-Wen Xu^{1

2}

Affiliations

¹ College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.
² College of Veterinary Medicine Sichuan Key Laboratory of Animal Epidemic Disease and Human Health, Sichuan Agricultural University, Chengdu, China.
³ Animal Breeding and Genetics Key Laboratory of Sichuan Province, Sichuan Animal Science Academy, Chengdu, China.
⁴ Livestock and Poultry Biological Products Key Laboratory of Sichuan Province, Sichuan Animal Science Academy, Chengdu, China.

Abstract

Porcine circovirus 4 (PCV4) was identified in 2019 as a novel circovirus species and then proved to be pathogenic to piglets. However, there is a lack of its prevalence in the Southwest of China. To investigate whether PCV4 DNA existed in the Southwest of China, 374 samples were collected from diseased pigs during 2021-2022 and detected by a real-time PCR assay. The results showed that the positive rate of PCV4 was 1.34% (5/374) at sample level, and PCV4 was detected in two of 12 cities, demonstrating that PCV4 could be detected in pig farms in the Southwest of China, but its prevalence was low. Furthermore, one PCV4 strain (SC-GA2022ABTC) was sequenced in this study and shared a high identity (98.1-99.7%) with reference strains at the genome level. Combining genetic evolution analysis with amino acid sequence analysis, three genotypes PCV4a, PCV4b, and PCV4c were temporarily identified, and the SC-GA2022ABTC strain belonged to PCV4c with a specific amino acid pattern (239V for Rep protein, 27N, 28R, and 212M for Cap protein). Phylogenetic tree and amino acid alignment showed that PCV4 had an ancient ancestor with mink circovirus. In conclusion, the present study was the first to report the discovery and the evolutionary analysis of the PCV4 genome in pig herds of the Southwest of China and provide insight into the molecular epidemiology of PCV4.

Keywords: genetic analysis; genotype; molecular detection; porcine circovirus 4; the Southwest of China.

Grants and funding

This work was supported by the Chongqing Municipal Technology Innovation and Application Development Project (No. cstc2021jscx-dxwt BX0007), the Key K&D Program of Sichuan Science and Technology Plan (No. 2022YFN0007), the Porcine Major Science and Technology Project of Sichuan Science and Technology Plan (No. 2021ZDZX0010-3), the Sichuan Provincial Department of Science and Technology Rural Area Key R&D Program (No. 2020YFN0147), and the Agricultural Industry Technology System of Sichuan Provincial Department of Agriculture (Project No. CARS-SVDIP).