Cloning and Molecular Characterization Analysis of M Gene of Porcine Epidemic Diarrhea Virus

In order to study the porcine epidemic diarrhea (PED) epidemic situation recently,small intestine tissue from piglets suspected porcine epidemic diarrhea virus (PEDV) were collected in this study. The PEDV M gene was amplified using RT-PCR method and the molecular characterization were analysed. The results showed that the ORF of M gene was 681 bp which encoded 226 amino acids. The percent identity of M gene amino acid between PEDV in this study and reference strains in GenBank were higher than 96.0%,and that with CH/SD-M/2012 strain was highest (96.9%).The phylogenetic tree based on the Neighbor-Joining (NJ) and Minimum-Evolution (ME) showed that the PEDV in this study was closely related to CH/SD-M/2012 strain which were belonged to the same evolutionary branch. The phylogenetic tree analysis illustrated that M gene of PEDV was relatively conservative. The results of homology modeling analysis found that crystal model of M protein was similar to coronavirus nsp14-nsp10 complex 5c8s.1 and NAD kinase Ⅰ 2i1w.1.B which shared 27.69% and 15.07% sequence similarity,respectively. The protein structure prediction analysis found seven α-helix structures located in 110 to 113,118 to 125,132 to 136,140 to 145,147 to 152,154 to 157 and 160 to 173 amino acid regions,and five ligand structures of zinc finger located in 98 to 100,102 to 107,135 to 137, 139 to 145 and 149 to 154, amino acid regions. The protein structure prediction analysis indicated that the M protein might be a polyprotein of viral genome replication enzyme.