CHOLERA-TOXIN (CTX) GENETIC ELEMENT IN VIBRIO-CHOLERAE O139
CHOLERA-TOXIN (CTX) GENETIC ELEMENT IN VIBRIO-CHOLERAE O139
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DOI：
10.1099/13500872-141-8-1977
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发表时间：
1995-08-01
期刊：
影响因子：
2.8
通讯作者：
DAS, J
中科院分区：
文献类型：
--
作者：
BHADRA, RK;ROYCHOUDHURY, S;DAS, J
对从印度不同疫区分离的O139霍乱弧菌的Noti和SfiI双酶切基因组进行的PFGE分析表明，所有菌株都是克隆起源，基因组大小约为2.2Mb。对0139株霍乱弧菌的基因组图谱、霍乱毒素(CTX)基因的限制性片段长度多态性(RFLP)以及未消化的经典株、El Tor和O139的基因组与经典株569B的Noti连锁克隆的Southern杂交分析表明，这些菌株与霍乱弧菌O1生物型El Tor非常相似，但与经典O1弧菌有很大的不同。利用限制性内切酶切割CTX基因元件核心区或直接重复序列(RS)中的单个位点，研究表明大多数O139菌株的基因组中有两个由两个RS串联连接的CTX基因副本。O139菌株中CTX基因元件的染色体位置与已报道的El Tor弧菌相同。不同O139株毒力基因盒的组织结构在群体中表现出遗传异质性。虽然大多数流行毒株都有两份CTX基因元件，但在一些毒株中，元件的数量已经扩大，至少在一种毒株中，该元件的一个副本已被删除。
PFGE analysis of the NotI- and SfiI-digested genome of Vibrio cholerae O139 strains isolated from different epidemic regions of India showed that all the strains are of clonal origin and the genome size is about 2.2 Mb. An analysis of the electrophoretic profiles of the genome of 0139 strains, the RFLP of the cholera toxin (ctx) gene and Southern blot hybridization of NotI-digested genomes of classical, El Tor and O139 with a NotI-linking clone of classical strain 569B, suggest that these strains closely resemble V. cholerae O1 biotype El Tor, but are widely different from the classical O1 vibrios. Using restriction enzymes which cleave a single site in either the core region or in the direct repeat sequence (RS) of the CTX genetic element, it has been shown that the genome of most of the O139 strains has two copies of the ctx gene in tandem connected by two RSs. The chromosomal location of the CTX genetic element in the O139 strain is the same as that reported for El Tor vibrios. The organization of the virulence gene cassettes in different O139 strains shows genetic heterogeneity in the population. Whilst most of the epidemic strains have two copies of the CTX genetic element, in some strains the number of elements has been amplified and in at least one strain a single copy of the element has been deleted.