title: Evaluation of a nested polymerase chain reaction assay to differentiate between two genotypes of Porcine circovirus-2.
abstract: Porcine circovirus-2 (PCV-2) is associated with several diseases in pigs, including postweaning multisystemic wasting syndrome (PMWS). A new genotype of PCV-2 was isolated from swine farms with and without clinical PMWS in North America. The new genotype was differentiated in a separate cluster by phylogenetic analyses and is now named PCV-2b compared with PCV-2a for the previously known genotype. The purpose of this study was to develop and evaluate a nested polymerase chain reaction (nPCR) assay to detect and differentiate between PCV-2a and PCV-2b. Genotype-specific primer sets were designed by using sequence data published for different PCV-2 strains. Specificity and sensitivity of the nPCR were examined by using PCV-2 isolates with known genotype. Nested PCR was found to be highly specific and sensitive for detecting and differentiating between the PCV-2 genotypes compared with the conventional 1-step PCR assay. Nested PCR was applied to detect PCV-2 and to identify the genotype in serum samples from swine farms with and without a clinical history of PMWS. Of 60 serum samples collected from 4 farms during clinical PMWS outbreaks, PCV-2a and PCV-2b were detected in 6 and 49 samples, respectively. Six of the 10 samples from one of the 4 farms had both PCV-2a and PCV-2b. Of 20 serum samples from 2 farms without PMWS, 11 were positive for PCV-2a only. These results suggest that the differential nPCR can be used to detect PCV-2 and to differentiate the 2 genotypes from field samples.
authors.affiliation: Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, USA.
authors.forename: Kwang Soo
authors.initials: KS
authors.lastname: Lyoo
authors.forename: Hyeun Bum
authors.initials: HB
authors.lastname: Kim
authors.forename: Han Soo
authors.initials: HS
authors.lastname: Joo
mesh_terms: D000818:Animals; D017925:Circovirus / Q000145:classification* / Q000235:genetics*; D005838:Genotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary*; D053570:Porcine Postweaning Multisystemic Wasting Syndrome / Q000097:blood / Q000175:diagnosis / Q000821:virology; D012680:Sensitivity and Specificity; D013552:Swine