Isolation, molecular and phylogenetic analysis of porcine encephalomyocarditis virus strain HLJ in China

Background Encephalomyocarditis virus (EMCV) is a positive single-stranded small RNA virus without envelope, which can infect a variety of mammals. Swine are the most susceptible animals, which can cause acute myocarditis and respiratory failure in piglets and reproductive failure in pregnant sows. Diseases caused by EMCV have a wide range of effects on the global swine industry. Methods The tissue grinding fluid of aborted fetus was inoculated on baby hamster kidney 21 (BHK-21) cells to obtain HLJ isolate by cell passage. The virus was identified by reverse transcriptase polymerase chain reaction (RT-PCR), electron microscopic observation and indirect immunofluorescence assay (IFA). HLJ strain was inoculated into mice for animal regression experiment. The whole genome of HLJ strain was amplified and sequenced. The molecular and phylogenetic analysis of its sequence was generated. Results HLJ strain caused the specific cytopathic effect (CPE) on BHK-21 cells and severe pathological changes in mice. Complete genome sequencing and multiple sequence alignment showed that the homology between HLJ strain and other isolates worldwide was 71.5–99.7%. Phylogenetic analysis showed that EMCV isolates fell into five clusters: lineage I, II, III, IV, and V based on the nucleotide sequences of the entire open reading frame (ORF) and VP1 gene. HLJ isolate was grouped into lineage I. Conclusions In this study, a strain of EMCV was isolated from an aborted fetus in Northeast China. The isolation of HLJ strain enriches the epidemiological database of EMCV.