Dataset Information

Prevalence of porcine circovirus type 3 in pigs in the southeastern Chinese province of Zhejiang.

ABSTRACT: BACKGROUND:Porcine circovirus type 3 (PCV3) was first reported in US in 2016. The virus was also identified later in China. Prevalence of PCV3 in Zhejiang province in southeastern China is not clear though it has been reported in many parts of China. RESULTS:PCV3 infection and its co-infection with other swine viral pathogens in pig herds of Zhejiang province were retrospectively investigated by quantitative PCR (qPCR) and its sero-prevalence by indirect ELISA. PCV3 was found positive in 67.1% of the 283 clinical samples taken from 2014 to 2017 as shown by qPCR. Single infection with PCV3 accounted for only one-third of the samples, and majority were of co-infections, predominantly with PEDV (41.6%) but generally low with other swine viruses. Indirect ELISA using the PCV3 capsid protein as the coating antigen revealed an average sero-positive rate of 52.6% (40.8 to 60.8%) in 2345 serum samples from 2011 to 2017, with earliest yet high positive findings in samples taken in 2012. Of 203 serum samples, the qPCR method showed more positive findings than ELISA (81.3% vs 56.2%). With 89 serum samples negative by ELISA, vast majority (n?=?81) were found positive by qPCR. There was negative correlation in levels of PCV3 DNA and anti-capsid antibody response. ORF2-based phylogenetic analysis revealed three major groups (PCV3a, PCV3b and PCV3c) of the 200 strains, 38 from this study and 162 reference strains from GenBank. Most of the strains from this study were clustered into PCV3c. Of the putative signature residues of the capsid protein (aa 24, 27, 77 and 150) relative to the three groups, only the PCV3a group strains showed a distinct pattern of residues VKSI (95% of the strains), while the other two groups did not have such a 'signature' pattern. CONCLUSIONS:Results from this study provided further evidence that the novel virus PCV3 was widely distributed in China and might have emerged in Zhejiang province before 2014, most probably back in 2012 when there was high PCV3 sero-prevalence. PCV3 might be viremic in pigs and could spread by fecal shedding.

SUBMITTER: Geng S

PROVIDER: S-EPMC6631677 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Prevalence of porcine circovirus type 3 in pigs in the southeastern Chinese province of Zhejiang.

Geng Shichao S Luo Hao H Liu Yajie Y Chen Cong C Xu Weicheng W Chen Yunlu Y Li Xiaoliang X Fang Weihuan W

BMC veterinary research 20190715 1

<h4>Background</h4>Porcine circovirus type 3 (PCV3) was first reported in US in 2016. The virus was also identified later in China. Prevalence of PCV3 in Zhejiang province in southeastern China is not clear though it has been reported in many parts of China.<h4>Results</h4>PCV3 infection and its co-infection with other swine viral pathogens in pig herds of Zhejiang province were retrospectively investigated by quantitative PCR (qPCR) and its sero-prevalence by indirect ELISA. PCV3 was found posi ...[more]

PMID: 31307451

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Project description:Porcine 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.In 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.The 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.

Project description:BackgroundPorcine circovirus type 2 (PCV2), a member of the genus Circovirus and family Circoviridae, is a closed, small, circular, and single-stranded DNA virus, and it is a crucial swine pathogen of porcine circovirus-associated diseases (PCVADs). PCV2 was first detected in PK-15(ATCC-CCL) cells in 1974, which has caused significant economic loss to the swine industry throughout the world. And the first case of PCV2 was reported in China in 2000. At present, PCV2d is the main genotype circulating widely in China.MethodsLymph samples were obtained from piglets with emaciation and respiratory disease in Guangxi province, China. The main pathogens were detected via PCR from lymph samples, and then PCV2-single positive samples were used to inoculate with PK-15 cells. After successive generations, the isolate was subsequently identified by polymerase chain reaction (PCR), immunofluorescence assay (IFA), Western blot (WB), and transmission electron microscopic (TEM). The full-length genome and genetic characterization of isolates were analyzed by Sanger sequencing. The TCID50 of the PCV2-GX-6 was determined by IFA, and the pathogenicity of PCV2 in BALB/c mice was analyzed via the mouse model.ResultsThe isolates were successfully isolated from clinical samples. The complete genome of PCV2-GX-4, PCV2-GX-6, PCV2-GX-7, PCV2-GX-11 and PCV2-GX-16 have been amplified, sequenced, and deposited in GenBank (accession no.: OR133747, OQ803314, OR133748, OR133749, OR133750). Homology and phylogenetic analysis with reference strains showed that the isolates belonged to the PCV2d genotype. The PCV2-GX-6 could be stably passaged more than 30 times in PK-15 cells. PCV2-GX-6 was identified by PCR, IFA, WB and TEM. The results of homology showed that PCV2-GX-6 was closely related to the reference strains PCV2-JS17-8 (GenBank accession no.: MH211363). Pathogenicity studies in mice have shown that PCV2-GX-6 can lead to growth inhibition of mice. Meanwhile PCV2-GX-6 caused the typical lesions of spleen, lung and kidney. The results of qPCR showed that PCV2 can effectively proliferate in the liver, spleen, lung, and kidney.ConclusionPCV2-GX-6 can successfully infect BLAB/c mice, effectively proliferate in major organs, and possessed high pathogenicity. In conclusion, combined with the genotype and pathogenicity of PCV2d currently prevalent, PCV2-GX-6 can be used as a candidate vaccine strain.

Project description:BackgroundEight different PCV2 genotypes with varying prevalence and clinical impact have been described so far. PCV2 infection is still widespread among the vaccinated population and several experimental studies have clearly demonstrated that there is no induction of a 100% cross-protective immunity between the PCV2 genotypes. Hence, PCV2a-based vaccines may be ineffective. In this longitudinal study, the PCV2 genotype and haplotype evolution in Austria in the years 2002 to 2017 was investigated by phylogenetic analysis of 462 bp-long sequences of the capsid protein gene (ORF2). The obtained findings may be of practical relevance for the future development of vaccination strategies.ResultsOne hundred thirty four of a total of 161 formalin-fixed and paraffin wax-embedded samples could be sequenced successfully. There was no significant influence of storage time on sequencing success or quality. PCV2a (8.2%), PCV2b (77.6%), PCV2d (13.4%), and PCV2g (0.8%) were found. PCV2d was first detected as early as in 2004. PCV2g was described once in 2009. Both global PCV2 genotype shifts were observed. PCV2a occurred with a low prevalence during the first study years only in samples from non-vaccinated swine herds and was gradually replaced by PCV2b until 2011. PCV2b was the most prevalent genotype over the whole study period and was detected in samples from vaccinated and non-vaccinated herds. During the last two study years, the prevalence of PCV2d increased, although at this point almost all herds were vaccinated. The haplotype diversity was high, but the nucleotide diversity was low. Especially for genotype PCV2b, an increase in haplotype diversity could be described during the first study years.ConclusionExtensive PCV2a-derived vaccination resulted in a reduction of prevalence and in a stabilization of genotype PCV2a, whereas genotypes PCV2b and PCV2d evolved as a consequence of natural and vaccination-induced selection. An ongoing virus circulation may be the result of reduced vaccine-induced protection.

Dataset Information

Prevalence of porcine circovirus type 3 in pigs in the southeastern Chinese province of Zhejiang.

Publications

Prevalence of porcine circovirus type 3 in pigs in the southeastern Chinese province of Zhejiang.

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