A nanoparticle-assisted PCR assay to improve the sensitivity for rapid detection and differentiation of wild-type pseudorabies virus and gene-deleted vaccine strains

Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a novel method for the rapid amplification of DNA and has been adopted for the detection of virus because of its simplicity, rapidity, and specificity. A nanoPCR assay was developed to detect and differentiate wild-type and gene-deleted pseudorabies virus (PRV). Three pairs of primers for nanoPCR developed in this study were selected from conserved regions of PRV, producing specific amplicons of 431 bp (gB), 316 bp (gE), and 202 bp (gG). The sensitivity of this assay using purified plasmid constructs containing the specific gene fragments was 100-1000 fold higher than conventional PCR. The PRV nanoPCR assay did not amplify porcine parvovirus, porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, porcine teschovirus, or African swine fever virus but produced three bands of expected size with PRV and two bands of expected size with the gene-deleted PRV-Bartha-K61. Of 110 clinical samples collected from seven provinces in China, 53% and 48% were positive for wild-type PRV according to the nanoPCR assay and virus isolation, respectively.