The development of a sensitive droplet digital PCR for quantitative detection of porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome (PRRS) is an infectious disease, resulting in important economic losses in pig farming. Prompt detection of PRRS virus (PRRSV) in the field samples is important for effective PRRS control. Droplet digital PCR (ddPCR) is a novel PCR technology, which offers good precision and direct quantification without using calibration curves. In this study, we established a ddPCR system for the sensitive and accurate quantification of PRRSV. Specificity of the assay was determined by the failure of amplification of other relevant viruses. Quantitative linearity, sensitivity and accuracy of ddPCR were compared to those of real time PCR for PRRSV testing. Both methods showed a high degree of linearity (R2 =∼1) and quantitative correlation, although ddPCR showed somewhat higher sensitivity than real time PCR. Collectively, our findings indicate that ddPCR might offer improved analytical sensitivity and specificity for PRRSV measurements.