犬瘟热病毒疫苗免疫逃逸株的血凝素基因变异研究

摘要

In order to understand whether new genotype emerged,we detected Canine distemper virus(CDV)in immunized dogs,breeding foxes and minks in different regions by amplification of nucleocapsid(N)and hemaggluti-nin(H)gene.13 strains from CDV-positive cases(8 minks,2 foxes and 3 dogs)were sequenced.The results showed that the 13 Chinese strains shared 99.1 %-100.0% nucleotide identity.Compared with those of other Chinese CDV strains isolated before 2012,four consistent amino acid changes,P200S,M263I,I542N and Y549H,were observed in the H coding sequence of CDV isolated from vaccinated animals,which contribute to an additional N-glycosylation site and antigenic epitope.All of the strains obtained from 13 samples were characterized as genotype Asia-1 accord-ing to the sequence analysis of the complete H gene,which was the sole genotype in minks in China.These findings provide a comprehensive understanding of current immune failure and the molecular epidemiology of CDV in China.%为了弄清是否有新基因型犬瘟热病毒出现，对山东省不同地区的免疫水貂、狐狸和犬进行了犬瘟热病毒检测，扩增了病毒核衣壳基因和血凝素基因（H），并对13个犬瘟热病毒山东株（8株貂源，2株狐狸源，3株犬源）血凝素基因进行了测序。结果表明，13个犬瘟热病毒山东株之间 H 基因核苷酸同源性为99．1％～100．0％，均为 Asia-1型，这也是我国目前水貂犬瘟热病毒唯一的基因型。与2012年之前的犬瘟热病毒中国分离株及疫苗株相比，13个毒株H 基因有4个氨基酸的一致性变异，即 P200S、M263I、I542N 和 Y549H，N-糖基化位点比 Onderstepoort 株多6或7个，比 CDV3株多3或4个。抗原性分析表明，与疫苗株相比，13株山东株在540－549位氨基酸出现一个新的抗原区域，210－230，327－347位的抗原区域也与疫苗株不同，这些变异可能是我国貂狐犬瘟热免疫失败的原因。