畜禽空肠弯曲杆菌cmp基因结构特点及ST型研究

The Research of Campylobacter jejuni cmp Gene Structure and ST Type in Livestock and Poultry

本试验旨在对分离自牦牛、猪和鸡的空肠弯曲杆菌(C.jejuni)主外膜蛋白基因(cmp)结构特点和基因序列型(ST)进行研究。共克隆分析了60株(牦牛15株、猪22株和鸡23株)空肠弯曲杆菌分离株cmp基因的完整编码框,构建进化树,并参照国外文献报道以核苷酸序列中的一个核苷酸不同,认为是不同的ST型为标准,进行序列分型。结果表明:60条cmp基因有13个不同的长度,含有7～10个预测的表面暴露的Loop环和15～20个抗原表位位点,在cmp基因序列中,可变的核苷酸和推导的氨基酸的位置主要集中于6个高变区,都位于预测表面暴露的环上,共鉴定出46个不同的ST型,另外发现2株(1株牦牛源和1株猪源)与结肠弯曲杆菌有重组现象的发生。研究显示中国国内的cmp基因存在丰富的遗传多样性,ST型结果显示与菌株的宿主源有一定联系。

The aim of this study was to study structure and ST type of the crop gene of C. jejuni from Yaks, pigs and chicken. The complete coding frame of crop gene from 60 C. jejuni isolates （15 from Yaks, 22 from pigs and 23 from chicken） was cloned and analyzed. Neighbor-joining phylogenetic tree was constructed and ST types were determined according to the ST typing standard reported by literature in which one nucleotide variation in a nucleotide sequence was con- sidered a different ST. The results indicated that there were 13 different sequence length types among 60 crop genes cloned. A total of 7-10 Loop links, 15-20 antigen epitopic sites were predic- ted in these sequences. The majority of variable nucleotides and putative amino acid positions con- centrated in 6 high variable areas, which located at the Loop links that exposed on the surface of C. jejuni. Forty-six ST types were identified in the 60 cloned sequences, moreover, the two strains （one from Yak and the other one from pig） recombined with the C. coli. There is strong phylogenetic variation within the C. jejuni cmp genes, and it is revealed that ST types of C. je- juni crop gene are associated with host resources and geographic origin of the isolates.