Genetic variation analysis of GP5 gene of PRRSV isolates in Guangdong province during 2014-2016

To investigate the variation in GP5 gene of porcine reproductive and respiratory syndrome virus （PRRSV），a total of 317 clinical samples were collected from 46 pig farms suspected of PRRSV infection druing 2014-2016. The GP5 genes of PRRSV-positive samples were sequenced and analyzed. Phylogenetic analysis showed that all the isolates belonged to the North America genotype，and these PRRSV GP5 genes had 82.4%-98.7% nucleotide and 78.6%-98.5% deduced amino acid identity to each other. Among them，two isolates formed subgenotype III，which were closely related to the NADC30 strain in the US. 10 isolates formed subgenotype IV，were closely related to the recently isolated novel field strains，QYYZ and GM2. This study would provide the basis for selection and improvement of vaccines and comprehensive prevention and control of PRRSV.