SYBR Green-based real-time PCR assay for the detection of porcine epidemic diarrhea virus
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Abstract
Porcine epidemic diarrhea (PED) is a contagious disease caused by its virus, classified within the genus Alphacoronavirus, family Coronaviridae. This virus causes diarrhea, vomiting and weight loss in pigs of all ages, especially in neonatal piglets, with morbidity and mortality of up to 100%. In Ecuador, the disease was diagnosed for the first time in 2014 by conventional or endpoint PCR. Currently, there is a need for an ultrasensitive and specific assay, which allows working a large number of samples to facilitate epidemiological surveillance of new outbreaks and detect carrier animals. A real-time PCR assay intercalating DNA dyes such as SYBR Green was developed and assessed to detect PED virus (PEDv) in swine feces with primers targeting the N-gene of the virus. A PEDv RNA standard synthesized in the laboratory was used in the assessment of the analytical sensitivity. The detection limit of the developed assay was determined to be 4 copies of PEDv RNA, compared to endpoint PCR which was 100 times more sensitive. Assay specificity was based on the possibility of detecting false positives using the melting curve. Cycle threshold (Ct) values in intra- and inter-assay analysis showed valid coefficients of variation. When assessing diagnostic performance, the assay detected 18 positive samples out of a total of 52 for 100 % agreement with the endpoint PCR. It is concluded that the developed SYBR Green-based real-time PCR assay is highly sensitive, specific, reproducible and rapid for the detection of PEDv in swine intestinal mucosa homogenates.
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National Center for Animal and Plant Health (CENSA)References
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