Establishment of a Duplex Fluorescent RT-PCR Assay for Detection of Classical Swine Fever Virus and Bovine Viral Diarrhea Virus
In order to simultaneously detect classical swine fever virus(CSFV)and bovine viral diarrhea virus(BVDV)in clinical samples from pigs,the specific primers and TaqMan probes were designed based on 5'UTR sequence of the two kinds of viruses,and a duplex fluorescent RT-PCR was established,the specificity,minimum detection limit and repeatability were evaluated. The results showed that the assay could react specifically with CSFV and BVDV only,but failed to crossly react with other viruses including pseudorabies virus(PRV),porcine reproductive and respiratory syndrome virus(PRRSV),transmissible gastroenteritis virus(TGEV),porcine epidemic diarrhea virus(PEDV)and porcine circovirus-2(PCV-2). The minimum detection limits were 27,36 and 32 copies/μL for the positive standard plasmid control of CSFV-5'UTR-RNA,BVDV-1-5'UTR-RNA and BVDV-2-5'UTR-RNA respectively. The coefficients of variation(CV)of intra-and inter-group ranged 0.11% to 1.20%,showing good reproducibility. Atotal of 152 tissue samples were tested for CSFV and BVDV by the assay,with the results of 16 CSFV positive samples,3 BVDV positive samples and 1 CSFV-BVDV dual positive samples,which were completely consistent with the national standard and the results of corresponding fluorescent RT-PCR assay specified in OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. In conclusion,the assay established in this study could be used for the detection of CSFV and BVDV in clinical samples,which provided an effective technical method for control and purification of the two diseases.