Insights into the epidemic characteristics and evolutionary history of the novel porcine circovirus type 3 in southern China

Abstract

Porcine circovirus type 3 (PCV3) is a newly identified circovirus from swine in the USA, China and Poland. This novel circovirus has been associated with porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure and multisystemic inflammation; moreover, PCV3 poses a potential threat to the swine industry. In this retrospective study, a phylogenetic analysis was conducted to address the epidemiology and evolutionary dynamics of this novel circovirus. The total positive sample rate of PCV3 was 26.7% (76/285) and has increased gradually over the past 3 years. Of these PCV3-positive samples, 22.3% (17/76) were coinfected with PCV2. PCV3 can be detected in multiple sample types with different positive rates, and the positive rate is highest among stillborn. We also divide PCV3 into three clades (PCV3a, PCV3b and PCV3c) based on two amino acid mutations (A24V and R27K) on the cap protein in this study. In addition, the origin of PCV3 was approximately 1966 and may have originated from a bat-associated circovirus. Our results suggested that PCV3 is widely distributed in southern China and has been circulating in swine herds for nearly half a century. PCV3 has evolved into different clades caused by mutations in cap proteins; thus, further research on PCV3 epidemiology should be conducted.

Detection and phylogenetic analysis of porcine circovirus type 3 in central China

“…Among the amplicons from the four strains, there were only point mutations, but no nucleotide deletions or insertions. Based on the sequence analysis and comparison with the US MN2016 strain (KX898030), eleven aa changes were observed; PCV3 strains from this study and all reference strains had D56N and K100T mutations, and the SP strain had nine unique changes (P59A, W72G, E73G, S77R, K100T, R132P, I150N, A152G, T179P and K204Q), whereas three Chinese strains (CN/Fujian‐5/2016, CN/Fujian‐12/2016 and CN/Henan‐13/2016), two South Korean strains (KU‐1602 and KU‐1604), the Brazilian BR/RS/6 strain, and 29160 strain from the United States contained S77T and I150L mutations, which were also found in a previous study (Fu et al., ). We concluded that PCV3 strains from central China exhibited rapid mutation, possibly by means of international trading from other countries.…”

“…() and Fu et al. (), who found that PCV3 could be detected as early as 2014 in Hebei Province and in February 2015 in Guangxi, Guangdong, Jiangxi, Fujian and Hunan provinces, respectively. Most recently, a retrospective study of PCV3 infection in China found that 6.5% of the porcine samples collected from eight provinces and one autonomous region (Guangxi, Guangdong, Hainan, Hunan, Yunnan, Sichuan, Qinghai, Zhejiang and Jilin) were PCV3 positive, with the earliest cases occurring in 1996.…”

“…Almost concomitantly, another research group in the United States found PCV3 in tissues of sows with PDNS, as well as in mummified foetuses aborted from such sows (Palinski et al., ). Subsequently, PCV3 was reported in China, Poland, South Korea, Brazil, Italy and the UK (Faccini et al., ; Fu et al., ; Kwon, Yoo, Park, & Lyoo, ; Stadejek, Wozniak, Milek, & Biernacka, ; Tochetto et al., ; Ku et al., ; Collins, McKillen, & Allan, ). The PCV3 genome comprises a circular single‐stranded DNA of 2,000 bp in length, consisting of two major open reading frames (ORFs).…”

“…The cap protein determines the antigenic characteristics of circoviruses (Nawagitgul et al., ); however, the cap protein of PCV3 shares only approximately 37% identity with that of PCV2. To date, PCV3 has been detected throughout commercial pig farms from 21 provinces or districts (i.e., Guangdong, Guangxi, Anhui, Chongqing, Fujian, Hebei, Henan, Hunan, Hubei, Jiangsu, Jiangxi, Liaoning, Shenyang, Jinlin, Zhejiang, Shandong, Gansu, Neimenggu, Beijing, Sichuan and Yunnan) in China (Fan et al., ; Fu et al., ; Ku et al., ; Zhai et al., ; Zhang, Luo, Liang, Li, & Cui, ). Therefore, this study aimed to investigate the occurrence of PCV3 DNA and its genetic characteristics, using tissue and serum samples from 41 pig farms in 14 cities in central China, from 2013 to 2017.…”

First detection of porcine circovirus type 3 in Colombia and the complete genome sequence demonstrates the circulation of PCV3a1 and PCV3a2

“…Phylogeny‐based studies searching for the origin of PCV3 show the oldest trace of origin around 1966 from bats circovirus (Fu et al . ). In pigs, the presence of PCV3 has been verified since 1996 in Spain, where it was also shown that there have not been many changes since then (Klaumann et al .…”