RT-PCR detection of porcine reproductive and respiratory syndrome virus based on the ORF5 gene in mainland China, 2012–2015

Abstract

Between January 2012 and December 2015, 13,567 clinical samples were collected from healthy pigs and pigs with a history of respiratory symptoms and/or reproductive disorders in 29 provinces of mainland China to detect porcine reproductive and respiratory syndrome virus (PRRSV). From these samples, 7490 were PRRSV-positive (average value, 55.21%). The annual PRRSV detection rate from 2012 to 2015 for each year is 45.67%, 55.99%, 56.91%, and 59.07%, respectively. Phylogenetic analyses revealed that the percentage of highly pathogenic PRRSV strains had a decreasing yearly trend, whereas the vaccine-like strains showed the opposite trend during the years 2012-2015. These data indicate that while the vaccine contributes to PRRSV prevention in China, it might also lead to serious problems. Specifically, we identified 12 NADC30-like PRRSVs during the years 2014-2015, suggesting potential transmission of the newly emerged PRRSV strains in China. Our data contribute to new information about the epidemiology of PRRSV.