鸡传染性支气管炎病毒地方分离株核蛋白基因的遗传变异分析

Genetic variations of N gene of infectious bronchitis virus strains isolated in Shanxi province

对2006-2009年从山西各地疑似传染性支气管炎的病例中分离到的7株IBV地方分离株的核蛋白基因片段进行序列测定及分析。结果发现,7株IBV地方分离株核蛋白基因有5株含有一个长1 230 bp的ORF,其余2株含有1 227 bp,编码410/409氨基酸残基组成的多肽,与常用疫苗株H120推导的氨基酸序列比对发现,存在基因突变现象。与GenBank中的34株国内外分离毒株核蛋白基因推导的氨基酸序列进行比较和分析,系统进化关系显示41株IBV毒株分属于4个群,至少有3个群在我国流行,7个分离株分布在第Ⅳ群中,第IV群大多来自我国的北方地区地方分离毒株,第Ⅱ群来自我国南方地区的部分地方分离毒株,从N基因推导氨基酸进化树上分析可见,我国的IBV地方分离毒株主要分布在第Ⅱ和第Ⅳ群中,具有较明显的地理区域性,可见IBV地方分离株在基因进化关系上形成了自己较为独立的进化群。

Seven infectious bronchitis viruses（IBVs） isolated from Shanxi province during 2006 to 2009 from chickens suspected to be infected with IBVs were sequenced and genetically and phylogenetically analyzed.Nucleocapsid protein（N protein） genes seven infectious bronchitis virus strains.The results showed that the N protein genes of the five isolates were composed of 1 230 nucleotides,the other two strains were composed of 1 227 nucleotides,encoding a polypeptide of 410 or 409 amino acid residues,respectively.Point mutations can be observed in the N genes of the seven isolates,compared with the H120 vaccine strain.Phylogenetic tree based on amino acid sequences of genes from seven IBV isolates and 34 reference IBV strains showed that these strains were classified into four distinct clusters and there are at least three groups of IBVs co-circulating in China.The seven isolates were in cluster Ⅳ which were mainly isolated in the northern part of China.The partial IBV isolated strains from the southern part of China formed cluster Ⅱ.Taken together,the results showed that most of IBVs isolated in China recent years were grouped into cluster Ⅱ and Ⅳ and formed distinct phylogenetic groups in China.