对国内分离的犬冠状病毒（CCoV）DXMV、V1和V2流行毒株膜蛋白（M）基因进行了扩增、测序和遗传进化分析。3个CCoV流行毒株M基因全长均为792bp，编码263个氨基酸，其中前17个氨基酸为信号肽。DXMV、V1和V2流行株与Insavc-1疫苗株M基因相比，核苷酸的同源性分别为92.6% 、90.9%和91.6%，推导的氨基酸序列的同源性分别为92.5%、92.0%和92.3% ，在M基因前1/3区域内存在变异，其中74-76、120-124和131-135三个区域变异较大。国内DXMV、V1、V2、NJ1和NJ1-17 5个流行株M基因核苷酸同源性为96.6%，推导的氨基酸序列同源性为96.4%，显示出很高的保守性。基于M基因的遗传进化分析表明，目前国内绝大多数CCoV流行毒株都属于CCoV基因II型，只有Fox3-1和Rac2-1两个毒株属于基因I型。另外，将DXMV株M基因亚克隆到pET28a中，在BL21(DE3)中实现了M蛋白的表达，表达量约占菌体蛋白的10.2%。

Membrane (M) protein genes of Canine coronavirus (CCoV) domestic strain DXMV, V1 and V2 were successfully amplified, sequenced and analyzed. The full length of all the M gene of DXMV, V1 and V2 strains was 792 bp, encoding 263 amino acids. The initial 17 amino acids as appeared to be a signal peptide. Compared with the strain Insavc-1, the identities of nucleotide sequences and deduced amino acid sequences were 92.6% and 92.5% for strain DXMV, 90.9% and 92.0% for strain V1, 91.6% and 92.3% for strain V2, respectively. The variation was mainly in the one third 5’ regions of M gene, particularly in the regions of the 74-76, 120-124 and 131-135 nucleotides. The identities of nucleotide sequences and deduced amino acid sequences among 5 domestic strains were 96.6% and 96.4%, respectively. Phylogenetic tree based on the M genes showed that most domestic strains belong to CCoV genotype II, while Fox3-1and Rac2-1 are classified into genotype I. The M gene of strain DXMV was subcloned into pET28a expression vector. The recombinant M protein was successfully expressed in BL21(DE3), which amounted to 10.2 percent of the total bacterial protein.