Abstract:We developed an assay for the detection and quantitation of porcine circovirus type 2 (PCV2) with the SYBR Green I-based real-time PCR. The real-time PCR provides a broad dynamic range, detecting from 10 3 to 10 11 copies of DNA per reaction. No cross-reactions were found in specimens containing PCV1. Because of the high sensitivity and specificity of the assay with a relatively rapid and simple procedure, real-time PCR can be used as a routine assay for the clinical diagnosis of PCV2 infection. In this study we applied real-time PCR assay to 80 clinical samples, collected from 40 pigs with postweaning multisystemic wasting syndrome (PMWS) and 40 healthy pigs in comparison with conventional PCR assay. In 56 of 80 samples, PCV2 DNA was detected by conventional PCR assay. All samples positive for PCV2 DNA in conventional PCR assay were also positive in real-time assay, and 12 of 24 samples that tested negative for PCV2 DNA in the conventional assay were tested positive in real-time PCR assay. Real-time PCR assay increased the number of samples in which PCV2 was detected by 15%. It is, therefore, considered to be a useful tool for the detection of PCV2.
Porcine circovirus type 2 (PCV2) is closely related to the postweaning multisystemic wasting syndrome (PMWS). In this study, the pig serum and tissue samples collected from different regions of Hangzhou District in Zhejiang Province of China between 2003 and 2005 were analyzed by enzyme-linked immunosorbent assay (ELISA) for PCV2 antibody and by polymerase chain reaction (PCR) for ORF2 gene. The results show that out of 1250 randomly collected serum samples, 500 sera (40%) were seropositive for PCV2. PCR results demonstrate that Hangzhou PCV2 with more than 50% Chinese PCV2 strains and French PCV2 formed Cluster A. Only one PCV2 from Hangzhou belonged to Cluster B with some other Chinese PCV2 and Netherlands's isolates. Cluster C consisted of PCV2 isolates from China, US, Canada, UK and Germany. The results indicate that the PCV2 infection was widespread in Hangzhou.
Porcine reproductive and respiratory syndrome (PRRS) and classical swine fever (CSF) cause significant economic losses to the swine industry worldwide. As both diseases cause similar symptoms, rapid and reliable detection of these diseases is essential for disease surveillance. A quantitative SYBR Green I-based reverse transcription-polymerase chain reaction (RT-PCR) is described for simultaneous and differential diagnosis. The established RT-PCR for the quantitation of PRRSV and CSFV cDNA was found to provide a broad dynamic range, detecting from 10(3) to 10(11) and 10(2) to 10(11) copies of cDNA per reaction, respectively. Sensitivity and specificity of this method were compared with those of conventional RT-PCR and both were equal or superior to the reference method. Reproducibility was tested and the assay was proved very reliable. The assay is timesaving, easy to handle, and highly sensitive and specific. Therefore, it is a powerful tool for detecting PRRSV and CSFV simultaneously for routine outbreak investigation.
Abstract:Infectious bursal disease virus (IBDV) was inactivated by two different chemicals-formaldehyde and binary ethylenimine (BEI). Formaldehyde was used at 0.1% and 0.2%, while BEI was used at concentrations of 0.001 and 0.002 mol/L. These four vaccines were tested for their efficiency in generating humoral immune response in different groups of broiler chicks. Both BEI-inactivated vaccines gave relatively higher antibody titers and were almost twice as efficient as formaldehyde-inactivated ones.
Sapoviruses, members of the family Caliciviridae, are genetically diverse and divided into multiple genogroups. Only a few complete genome sequences of animal strains are available. We report the first complete genome sequences of genogroup VI sapoviruses, those of strains JJ674 and JJ681, isolated from fecal samples from diarrheic pigs.
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