Ring tests to evaluate the performance of Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays used in North American diagnostic laboratories.

Two laboratory studies involving 11 laboratories were undertaken to assess the performance of North American Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays. Laboratories received identical submissions containing randomly coded positive and negative control samples, and serially diluted PCV-2-spiked samples. In study 1 and 2, respectively, spiked samples contained measured amounts of PCV-2 virus or DNA. All but 1 assay detected DNA in the most concentrated spiked sample. There were no statistical differences in the proportion of positive or negative samples reported by quantitative (n = 7) versus non-quantitative (n = 6) assays. Across both studies, the false positive rate was 17% (4 out of 23), and 17% (2 out of 12) of assays cross-reacted with PCV-1. The most sensitive assay detected PCV-2 DNA levels about 100 000 times lower the least sensitive assay. This study demonstrated that the PCR assays available in North American diagnostic labs vary considerably in their detection limits and quantification.