Comparative epidemiology of porcine circovirus type 3 in pigs with different clinical presentations

Abstract

BackgroundPorcine circovirus type 3 (PCV3), as an emerging circovirus species, was reported to be widely circulating in the United States, China, South Korea and Poland. Previous studies revealed that PCV3 was mainly concentrated in sick animals with respiratory disease, skin disease, reproductive disorders and so on. However, the circulating status of PCV3 in pigs with other clinical presentations (especilly asymptomatic or diarrhea) was not well established.FindingsIn this study, to conduct a comparative epidemiological survey of PCV3, 80 weaned pig serum samples with severe respiratory disease (SRD), 175 weaned pig serum samples with mild respiratory disease (MRD), 216 asymptomatic weaned pig serum samples, 35 diarrheal weaned pig samples and 35 non-diarrheal weaned pig samples were collected from eight provinces of China. Via qPCR testing, PCV3 was circulating in all sampling provinces, with total positive rates varying from 1.04% to 100%. Interestingly, the PCV3-positive rate was significantly higher in weaned pigs with SRD (63.75%, 51/80) than in those weaned pigs with MRD (13.14%, 23/175) and asymptomatic pigs (1.85%, 4/216) (P < 0.01). Similarly, the PCV3-positive rate was significantly higher in diarrheal weaned pigs (17.14%, 6/35) than in non-diarrheal weaned pigs (2.86%, 1/35) (P < 0.05). Moreover, the lower Ct values of qPCR were frequently found in those weaned pigs or fattening pigs with respiratory disease and diarrhea rather than that in asymptomatic pigs. Sequence analysis showed that low genetic diversity existed among those PCV3 sequences collected from pigs with different clinical presentations.ConclusionsThe present study further extends evidence that newly described PCV3 widely circulates in six additional provinces of Southern and Northern China and has high similarity to previously reported isolates. As an emerging virus of swine, although the present case-control study reveals that PCV3 has a potential association with swine respiratory disease and diarrhea, further investigations into the pathogenesis are needed to ascertain the role of PCV3 in swine health.Electronic supplementary materialThe online version of this article (10.1186/s12985-017-0892-4) contains supplementary material, which is available to authorized users.

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

“…In the present study, PCV3 was detected in samples from pigs with different clinical presentations, and the PCV3‐positive rates were different for different clinical presentations, showing rates of 73.33% (11/15), 46.15% (12/26), 27.78% (10/36), 23.38% (18/77), 13.33% (2/15) and 0% (0/1) for PDNS, sows who underwent abortions and stillbirths, diarrhoea, PMWS, respiratory symptoms and piglets with neurological symptoms, respectively. The results showed that there was a higher PCV3 detection rate in samples from pigs with diarrhoea, which is similar to results reported previously (Zhai et al., ; Wang, Zhang, Zhang et al., ), suggesting PCV3 might have a potential association with swine diarrhoea. Furthermore, PCV3 and PEDV were simultaneously detected by our group in diarrhoeal samples in another study (data not shown).…”

“…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.…”

Retrospective detection of Porcine circovirus 3 (PCV-3) in pig serum samples from Spain

“…Some studies identified the presence of PCV‐3 in several tissue samples or sera from pigs with different clinical presentations (Palinski et al., ; Tochetto et al., ; Zhai et al., ), as well as in healthy animals (Franzo, Legnardi, Hjulsager et al., ; Franzo, Legnardi, Centelleghe et al., ; Zheng et al., ). The data compiled in this study suggest a homogeneous PCV‐3 frequency in the different production phases and clinical/pathological conditions, as no statistically significant differences were found among tested groups.…”

“…Recently, Zhai et al. () found lower qPCR Ct values in samples from animals with respiratory signs and diarrhoea compared to those of asymptomatic animals, suggesting that PCV‐3 may be potentially associated with these clinical conditions. A recently described qPCR for PCV‐3 detection (Franzo, Legnardi, Centelleghe et al., ) was attempted in the present study with a limited number of positive samples as an exploratory approach (data not shown).…”

“…It was initially found in 2016 in tissues of swine affected by porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure, and cardiac and multisystemic inflammation (Palinski et al., ; Phan et al., ) in the USA. Subsequently, other reports from Europe (Collins, McKillen, & Allan, ; Faccini et al., ; Franzo, Legnardi, Hjulsager et al., ; Stadejek, Woźniak, Miłek, & Biernacka, ), Asia (Fan et al., ; Ku et al., ; Kwon, Yoo, Park, & Lyoo, ; Shen et al., ; Zhai et al., ; Zheng et al., ) and South America (Tochetto et al., ) described the presence of PCV‐3 genome in tissue samples or sera from pigs with different clinical presentations as well as in healthy animals.…”