Development of a TaqMan allelic discrimination assay between wild-type and vaccine isolates of porcine epidemic diarrhea virus (PEDV)

A one-step reverse-transcription polymerase chain reaction (RT-PCR) assay using TaqMan minor-groove-binding (MGB) probes was developed to distinguish between the oral vaccine and other strains (wild-type and conventional vaccine type) of porcine epidemic diarrhea virus (PEDV) in Korea. Although an attenuated DR13 strain has been used in animal vaccinations in Korea, porcine epidemic diarrhea (PED) remains a serious problem and a practical approach to differentiate oral vaccine and other field strains in fecal samples is needed. We examined the fluorescence of nine wild-type strains (three conventional vaccine strains [KPED9, SM98P and DR13] and six field strains) and one attenuated DR13 oral vaccine. Three clusters of the samples could be distinguished: those with fluorescence of only the oral vaccine-specific probe, VIC; those with fluorescence of only the wild-type and conventional vaccine-specific probe, NED; and those with both VIC and NED fluorescence. The RT-PCR assay with TaqMan MGB probes is sensitive and accurate, and is therefore useful for differentiating the oral vaccine from other strains of PEDV in Korea.