Detection of PCV2e strains in Southeast China

Abstract

Porcine circovirus 2 (PCV2) has been prevalent in swine herds in China since 2002, causing severe economic loss to the pig industry. The number of live pigs in southeast China is > 20 million. Since information on the genetic variation of PCV2 in the Fujian province is limited, the objective of the present work was to investigate the epidemiological and evolutionary characteristics of PCV2 in southeast China from 2013 to 2017. Of the 685 samples collected from 90 different swine herds from 2013 to 2017, 356 samples from 84 different swine herds were positive for PCV2. PCV2a, PCV2b, PCV2d, and PCV2e co-existed in the Fujian province, with PCV2d being the predominant circulating strain in swineherds and PCV2e being reported for the first time in China. Strikingly, PCV2-FJ-water DNA comes from contaminated river water and not infected animals. Sequence comparison among all isolates indicated that 95 isolates shared approximately 78.7%–100% nucleotide identity and 74.5%–100% amino acid identity for open reading frame 2 (ORF2). Amino acid alignment showed that the Cap protein of PCV2e differed markedly from those of PCV2a, PCV2b, PCV2c, and PCV2d. These results indicated that various PCV2 genotypes exist in China, and that PCV2 is continuously evolving, leading to rapid emergence of new variant stains.

Emergence of a novel recombinant porcine circovirus type 2 in China: PCV2c and PCV2d recombinant

“…Notably, recombination is very important for viral evolution and may modify the virulence and pathogenicity of PCV2. Inter‐genotypic and intragenotypic recombination between PCV2 has been reported in both in vitro studies and field conditions (Cai et al, ; Franzo, Cortey, Segalés, Hughes, & Drigo, ; Guo et al, ; Jiang et al, ; Liu et al, ; Liu, Wang, Zhu, Sun, & Wu, ; Wang et al, ). Notably, recombination events between PCV1 and PCV2 have also been detected (Gagnon, Music, Fontaine, Tremblay, & Harel, ).…”

“…Many reports have revealed that PCV2a, PCV2b, PCV2d and PCV2e exist in China. In the past few years, PCV2b and PCV2d have been the predominant genotypes identified in Chinese swine herds (Cai et al, ; Guo et al, ; Jiang et al, ; Liu et al, ; Wang et al, ). Furthermore, different genotypes or different groups within the same genotype of PCV2 may coexist in the same swine herd in China, which may facilitate virus recombination (Cheung, ; Zhai et al, ).…”

“…Notably, recombination events between PCV1 and PCV2 have also been detected (Gagnon, Music, Fontaine, Tremblay, & Harel, ). More importantly, the high frequency of PCV2 recombination enhances the emergence of new variants and results in a serious challenge to PCV2 classification (Cai et al, ; Franzo et al, ; Hesse, Kerrigan, & Rowland, ; Liu et al, ; Wang et al, ).…”

“…PCV2a, PCV2b and PCV2d are currently prevalent worldwide (Franzo et al, ; Guo, Lu, Wei, Huang, & Liu, ; Xiao et al, ), while PCV2c has been detected only in the Brazilian Pantanal (Franzo et al, ) and Denmark (Dupont, Nielsen, Baekbo, & Larsen, ). Porcine circovirus‐associated diseases was first reported in swine herds of China in 1999 with predominance of PCV2b and PCV2d during the period 2004–2009 (Jiang et al, ; Lang, Zhang, Wu, & Zhang, ; Liu et al, ). Additionally, a minor PCV2 group emerged in China via intragenotypic or inter‐genotypic recombination.…”

Molecular epidemiology and genetic variation analyses of porcine circovirus type 2 isolated from Yunnan Province in China from 2016-2019

“…PCV2e is a new genotype that has been circulating in the USA since 2015, the ORF2 sequences of which have 12 or 15 additional nts (CTT/TCTTA-TATGTAA) compared to those of PCV2a-PCV2d. PCV2e was reported in China for the first time in 2017 [14,15]. Intermediate and new genotypes have been proposed, with increasing numbers of sequences available in recent years.…”