Development and evaluation of rapid detection of classical swine fever virus by reverse transcription loop-mediated...

A one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed for the detection of classical swine fever virus (CSFV) and a set of primers designed based on the E2 gene reference sequences of the CSFV. The assay was optimized to amplify CSFV RNA by incubation at 63 degrees C for 50 min. The RT-LAMP amplification products had a ladder-like appearance when electrophoresed on an agarose gel. The RT-LAMP assay showed higher sensitivity than the conventional RT-PCR, and no cross-reactivity appeared with other related porcine viruses including porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus (PRRSV). The positive predictive value (PPV) of CSFV RT-LAMP for 227 field tissue samples was 94.7%, the negative predictive value (NPV) was 30.8% and showed better for the conventional RT-PCR method. Thus, the RT-LAMP assay is extremely rapid, sensitive, and specific and has potential usefulness for rapid laboratory diagnosis and pen-side detection for CSFV detection in pigs.