Abstract
BackgroundPorcine epidemic diarrhea virus (PEDV) is a pathogen causing serious disease and resulting in severe economic losses in the swine industry. In recent years, although China has adopted a large-scale vaccine immunization strategy, many types of PEDV strains, including classical attenuated vaccine strains, have been discovered in the immunized pig herds. Therefore, monitoring the prevalence of different types of PEDV strains is particularly important for the production of pigs and the safety evaluation of related attenuated vaccines MethodsIn the study, a one-step real-time fluorescent reverse transcription PCR (one-step real-time RT-PCR) assay targeting 24-nucleotide deletion in the ORF1 region of three PEDV classical attenuated vaccine strains (derived from classical strains) was established, which could effectively distinguish PEDV classical attenuated vaccine strains and wild-type strains. ResultsIn our study, the RNA detection limits for PEDV wild-type strains and classical attenuated vaccine strains were 3.0×103 copies and 3.0×102 copies, respectively. This assay was highly specific for PEDV, with no cross-reactivity for other viruses, causing diarrheal disease. A total of 117 swine fecal samples were analysed by this established real-time RT-PCR assay, indicating that classical attenuated vaccine strains were present in the swine herds in Gansu province, China. Additionally, a pair of primers and two probes of the established assay can be placed in one reaction tube to distinguish PEDV classical attenuated vaccine strains and wild-type strains. ConclusionOur results provided an effective and cheap technology platform for clinical rapid identification testing and epidemiological investigations of PEDV wild-type strains and classical attenuated vaccine strains