空肠弯曲菌中规律成簇间隔短回文重复序列（CRISPR）的检测与结构分析

规律成簇间隔短回文重复序列（clustered regularly interspaced short palindromic repeats，CRISPR）是近年在原核生物中发现的针对噬菌体等外源遗传物质的干扰而进化出的获得性和可遗传性生物免疫系统。因其序列的高度多态性及携带遗传信息的可追溯性，成为分子分型方法的理想位点。本研究对江苏地区分离的86?株空肠弯曲菌基因组进行CRISPR结构的检测和分析。结果表明：36%的菌株基因组含有CRISPR结构，32?株含有确定CRISPR结构的菌株均只含有1?个CRISPR结构，CRISPR序列长度范围为92～366?bp；重复序列与数据库中出现频率最高的重复序列一致；识别到的间隔序列共111?条，共分为17?种类型，有10?种类型的间隔序列与CRISPR?DB数据库中公布的一致，有7?种间隔序列为新报道的间隔序列，共55?条，占总间隔序列的49.5%。通过同源性比对发现，间隔序列除与来自同属同种的质粒或噬菌体具有同源性外，有些还与其他致病菌的质粒或噬菌体具有同源性，这种现象说明空肠弯曲菌与其他致病菌可能存在基因的水平转移等信息交流方式。另外，通过CRISPR结构间隔序列的多样性，可以将38?株空肠弯曲菌野生菌株分为5?种不同的谱型。研究结果为空肠弯曲菌利用CRISPR结构进行分型和溯源提供数据基础。

Detection and Structural Analysis of Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) Regions in Campylobacter jejuni

Clustered regularly interspaced short palindromic repeats (CRISPRs) are?an adaptive, heritable immune system found in prokaryotes that confers resistance to exogenous?genetic?elements?such as phage. CRISPRs are considered an ideal target for molecular subtyping because they have a high diversity and carry traceable genetic information. In this study, the genomic CRISPR structure in 86 strains of Campylobacter jejuni isolated in Jiangsu province was analyze by bioinformatic methods. The results showed that 36% of these strains contained CRISPRs in their genomes and 32 strains were found to have only one CRISPR 92–366 bp in length. The direct repeats detected in this study were identical to those in the CRISPR database. A total of 111 spacers were recognized and they were classified into 17 different clusters based on their sequences, 10 clusters of which have been previously recorded in the CRISPR db database while the 7 others were reported for the first time, consisting of 55 (49.5%) of the 111 spacers. Homology analysis showed that there was a high similarity in the spacer sequences between different phages and plasmids from the same genus or species as well as those from other pathogenic bacteria, which suggested that horizontal gene transfer (HGT) may play an important role in the bacterial communication between C. jejuni and other pathogens. Besides, 38 wild strains of C. jejuni were grouped into 5 patterns based on the CRISPR structure diversity. The results of this study can provide essential data for subsequent molecular subtyping and traceability of C. jejuni.