Identification and genetic characterization of porcine hemagglutinating encephalomyelitis virus from domestic piglets in China

In this study, we investigated an acute outbreak of porcine hemagglutinating encephalomyelitis on a farm of 127 pigs in Jilin province, China. Porcine hemagglutinating encephalomyelitis virus (PHEV) was detected in suckling and weaning pigs by RT-PCR assays. Coronavirus-like particles were observed by electron microscopy. The virus isolate was designated PHEV-JT06. The clinical signs, nervous symptoms and positive labeling of neurons in the cerebral cortex with an immunohistochemical stain in PHEV-JT06-infected BALB/c mice supported the diagnosis of PHEV infection. The five full-length PHEV-JT06 structural genes were cloned, sequenced and analyzed. Phylogenetic studies based on the nucleotide and amino acid sequences of the five genes in the outbreak showed that PHEV remained genetically stable. PHEV shares 95.3-99.3 % amino acid sequence identity with American strains (AY078417), suggesting that the Chinese isolate is most likely derived from the North American strain. Additionally, PHEV, HCoV-OC43 and BCoV were genetically close. These results may provide some insights into the genotype of the etiological agent responsible for the porcine hemagglutinating encephalomyelitis outbreak and could also provide a comparative view of the genomics of the five structural proteins of PHEV.