Identification and characterization of atypical porcine pestivirus genomes in newborn piglets with congenital tremor in China.

Recently, a novel atypical porcine pestivirus (APPV) in pig was reported. In this study, two APPV strains, APPV-China/GZ01/2016 (GZ01) and APPV-China/GD-SD/2016 (GD-SD), were identified in two newborn piglet herds with congenital tremor from China. The open reading frame of the two strains shared an 83.5% nucleotide identity. Phylogenetically, the APPV strains were placed into two groups: GZ01 belonged to group I and GD-SD belonged to group II. A high viral load was detected in the cerebellum (quantification cycles ＜ 26). Further studies should be carried out to thoroughly elucidate the development of congenital tremors caused by APPV.

Pathogenicity of a newly emerged recombined porcine reproductive and respiratory syndrome virus strain (subgenotype III) in China.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a severe pathogen that causes enormous economic losses to the swine industry worldwide. Since its first report in the 1980s, PRRSV has undergone extensive variation. In the previous study, we demonstrated that the GDsg strain was a new recombined virus between the low pathogenic field strain QYYZ and the vaccine strain JXA1-P80, belonging to the newly emerging type 2 PRRSV subgenotype III. In this study, the pathogenicity of a new recombined strain GDsg for pigs was analyzed. The results of in vivo experiments indicated that GDsg could cause persistently high fever, severe interstitial pneumonia, and high viremia and antibody levels in inoculated piglets. In particular, the brains of inoculated pigs exhibited serious hemorrhage and microscopic lesions. These results suggested that compared with the low pathogenic field strain QYYZ and the vaccine strain JXA1-P80, the new recombined GDsg strain had higher virulence in pigs. This study will help to characterize the relationship between recombination and evolution of PRRSV.