A molecular survey reveals high occurrence of co-infections in intensive pork production farms with increased rates of mummified swine fetuses in Southern Brazil / [Pesquisa molecular revela alta ocorrência de coinfecções em granjas de produção intensiva de suínos com altas taxas de mumificação fetal no sul do Brasil]

Neste estudo, 308 amostras de fetos mumificados foram testadas para parvovírus suíno (PPV), circovírus suíno tipos 2 e 3 (PCV2 e PCV3) e leptospiras patogênicas. A idade gestacional no momento da perda gestacional e a frequência da mumificação fetal de acordo com a ordem de parto também foram investigadas. As amostras foram coletadas em granjas comerciais de criação de suínos da região sul do Brasil que apresentassem taxas de mumificação fetal igual ou maiores a 2,5%. Fragmentos de pulmão, rim, fígado e coração de fetos suínos mumificados foram coletados para análise molecular. Resultados da PCR foram classificados de acordo com a região de origem das amostras, tendo Santa Catarina, Paraná e Rio Grande do Sul contabilizado 87 (28,25%), 89 (28,90%) e 132 (42,86%) do total de amostras de fetos suínos mumificados, respectivamente. Coinfecções foram observadas na maioria dos casos e PCV3 foi o agente mais prevalente detectado, encontrado em 298 amostras (96,75%). A maioria das perdas gestacionais foi observada entre 50 e 70 dias de gestação (168; 54,5%) e a mumificação fetal não foi associada à ordem de parto das matrizes. Os achados sugerem que as altas taxas de fetos suínos mumificados na região Sul do Brasil podem ser explicadas pela infecção com esses agentes virais.(AU)

First detection and genetic characterization of porcine parvovirus 7 from Korean domestic pig farms

Porcine parvovirus 7 (PPV7) was first detected in Korean pig farms in 2017. The detection rate of PPV7 DNA was 24.0% (30/125) in aborted pig fetuses and 74.9% (262/350) in finishing pigs, suggesting that PPV7 has circulated among Korean domestic pig farms. Phylogenetic analysis based on capsid protein amino acid sequences demonstrated that the nine isolated Korean strains (PPV-KA1-3 and PPV-KF1-6) were closely related to the previously reported USA and Chinese PPV7 strains. In addition, the Korean strains exhibit genetic diversity with both insertion and deletion mutations. This study contributes to the understanding of the molecular epidemiology of PPV7 in Korea.

Evaluation of safety and immunogenicity of a new octavalent inactivated vaccine containing porcine parvovirus, erysipelas, and leptospira

Porcine parvovirus, Erysipelothrix (E.) rhusiopathiae, and Leptospira (L.) interrogans are considered major etiologic agents of reproductive failure in pigs, causing economic loss in the swine industry. In this study, the safety and immunogenicity of a new octavalent inactivated vaccine were evaluated. The vaccine contained inactivated porcine parvovirus, E. rhusiopathiae, and six L. interrogans serovars (Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona). Safety test results showed no notable side effects or clinical signs after vaccination in mice, guinea pigs, and sows. In addition, we assessed immunogenicity of the vaccine in 25 sows under field conditions. The vaccinated group (n = 20) had a significantly higher antibody level than the non-vaccinated group (n = 5). Moreover, the stillbirth rate decreased in piglets born from vaccinated sows, resulting in an increased fertility rate. The results of this study demonstrate that the new octavalent inactivated vaccine can be applied safely and effectively to improve reproductive performance in sows.

Establishment and preliminary application of an assay for the detection of porcine parvovirus in cells used for production / 中华微生物学和免疫学杂志

Abstract] Objective To establish an assay for the detection of porcine parvovirus ( PPV) and to verify its application for monitoring cells used for production.Methods A pair of primers and one probe were designed according to the conserved sequence encoding non-structural protein 1 (NS1).Based on the designed primers, a real-time fluorescent quantitative PCR assay for the detection of PPV was developed. Several parameters including the linearity, precision, minimum detection limit and anti-interference of the established assay were evaluated.A stock of PPV strains was prepared by infecting swine testicle ( ST) cells with PPV strains.An assay for the detection of PPV infection was developed by using ST cells as sensitive cells.A combined ST cell infection-PCR test was developed by combining the ST cell infection assay with the real-time fluorescent quantitative PCR assay.The sensitivity of ST cell infection-PCR test was analyzed.The cell samples used for production of biological products were detected by using the established assay.Results The real-time fluorescent quantitative PCR assay was specific for the detection of PPV without cross-reaction to other species of parvovirus virus, SV40 virus and other porcine viruses.The linear range of the assay was 1×109-1×104 copies/μl with a R2 value more than 0.98.The sensitivity of the real-time quantitative PCR assay was 1×104 copies/μl.Both of the intra-and inter-coefficient of variation (CV) were less than 5%in Ct values.The intra-and inter-CV in copies of detection were 5%-15% and 30%-40% respectively.The minimum detection limit of the real-time fluorescent quantitative PCR assay was 1CCID50/ml.The PPV strains were detected in cell samples with no interference.The sensitivity of ST cells infection-PCR test was 0.01CCID50/ml.All of the 22 cell samples were negative for PPV by using the real-time fluorescent quanti-tative PCR assay.Conclusion The real-time fluorescent quantitative PCR and the ST cell infection-PCR test for the detection of PPV in cells were established successfully.The application of the two assays was conducive to further enhance the safety of using cells for production and therapy.

Prevalence of porcine parvovirus in pigs with postweaning multisystemic wasting syndrome in Jeju Island / 대한수의학회지

Postweaning multisystemic wasting syndrome (PMWS), which was first identified in western Canada in 1991 and more recently in the United States, Europe and Asia, is an emerging disease in pigs. Porcine circovirus type 2 (PCV-2) is the primary infectious viral agent causing PMWS, but the full expression of the disease may require the presence of other agents. It is reported that there is apparent synergism between PCV-2 and porcine parvovirus (PPV) in increasing the severity of the clinical signs and lesions of PMWS. From January 2006 to May 2008, a total of the 154 lymph node samples were collected from 4~12 weeks old pigs which had been submitted to the College of Veterinary Medicine, Jeju National University, Korea. These pigs were diagnosed as PMWS on the basis of clinical and pathological examination from 48 commercial herds in Jeju Island. Based on the immunohistochemistry, porcine parvovirus was detected in 69 cases (44.8%) from 154 weaned or grower pigs. PPV antigens were detected in the cytoplasm of histiocytic cells multifocally infiltrated in the cortex and paracortex of lymph nodes. The results of this study clarify that PPV is prevalent in pigs with PMWS on Jeju Island. Therefore PPV is one of the most important co-agents in the development of naturally acquired PMWS. This study may be helpful to the control of this disease and to epidemiological aspects.

Obtaining of union expression virus-like particle of PPV VP2 and PCV2 ORF2 and its immunogenicity / 中国兽医学报

The amplified VP2 gene (PPV strain SC-1) and PCV20RF2 gene were inserted into the eukaryotic expression vector pPI-2.EGFP.Then the recombinant plasmid named pPI-2.EGFP.VP2.ORF2 was obtained.Mediated by liposome,the recombinant plasmid was transfected into Veto cells and expressed.Using immunofluorescence assay,the fluorescence of expression products were first detected at 20 h after transfection and peaked 36 h.Under electronmicroscope,virus-like particles (VLPs) can be observed in the transfected cells.To confirm the obtained VLPs to be recombinant particles,piglets were immunized using purified VLPs.The dynamic variation of blood T lymphocytes and serum antibody level of PPV and PCV2 were measured.The results showed that the ratio of CD3+,CD4+ T lymphocyte in peripheral blood lymphocyte of immunized piglets raised in a certain degree,the number of CD8+ T lymphocytes fell at 7-14 d after immunization,and then raised.Relatively high level of PP-V,PCV2 specific antibody could be detected.This indicated that the expression of recombinant plasmid pPI-2.EGFP.VP2.ORF2 was successful,the virus-like particles were formed and showed favourable immunogenicity.

Molecular basis for porcine parvovirus detection in dead fetuses

Reproductive failures are still common grounds for complaint by commercial swine producers. Porcine parvovirus (PPV) is associated with different clinical reproductive signs. The aim of the present study was to investigate PPV fetal infection at swine farms having ongoing reproductive performance problems. The presence of virus in fetal tissues was determined by nested-polymerase chain reaction assay directed to the conserved NS1 gene of PPV in aborted fetuses, mummies and stillborns. Fetuses show a high frequency of PPV infection (96.4%; n = 28). In 60.7% of the fetuses, PPV were detected in all tissue samples (lung, heart, thymus, kidney, and spleen). Viral infection differed among fetal tissues, with a higher frequency in the lung and heart (p < 0.05). Fetuses with up to 99 days of gestational age and from younger sows showed a higher frequency of PPV (p < 0.05). No significant difference in the presence of PPV was detected among the three clinical presentations. The results suggest that PPV remains an important pathogenic agent associated with porcine fetal death.

Partial Nucleotide Sequence of Porcine Parvovirus (VRI-1 Strain): Identification of the Putative Defective Genomes

A porcine parvovirus, designated as VRI-1, was isolated from a 30-day-old piglet. Replicative form of viral DNA from ST cells infected with VRI-1 was directly cloned into pUC19. The cloned DNA fragment contained the entire nonstructural and structural protein genes, covering approximately 85% of the viral genome. The nucleotide sequence of VRI-1 showed 99.4~99.5% identity in the nonstructural protein (NS) and 99.0~99.2% identity in the structural protein with previously reported PPV strains, respectively. Among the cloned genes, two types of defective genomes with deletion of 100 and 247 nucleotides at almost similar location of 3' region within NS gene were also identified in this study.