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Study on correlation between virulence and molecular structure of type-specific antigen of Rickettsia tsutsugamushi

恙虫病立克次体毒力与型特异性抗原分子结构相关性研究

基本信息

批准号：
03454185
负责人：
TAMURA Akira
金额：
$ 3.26万
依托单位：
Niigata College of Pharmacy
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03454185/
关键词：
Rickettsia tsutsugamushi antigenic type type-specific antigen 56-KDa protein virulent factor cloning and sequencing of gene PCR restriction enzyme fragment polymorphism 恙虫病型特異抗原 R.tsutsugamushi 遺伝子クロ-ニング病原性恙虫病診断シグナルペプチド

项目摘要

Various antigenic variants are recognized in Rickettsia tsutsugamushi, and our previous studies indicated the relationship between the antigenic type of this rickettsia and its virulence to mice. Because the antigenic variety of this microorganism is due to the type-specific antigen of 56-KDa protein located on the rickettsial surface, the difference of virulence in each strain seems to depend on the molecular structure of this protein. In this study, the whole molecular structure of 56-KDa proteins originated from high-virulent strains of Gilliam, Karp and Kato, and from low-virulent strains of Kawasaki, Kuroki and Shimokoshi, were determined by chemical analysis of purified 56-KDa proteins, and by cloning and sequencing methods of 56-KDa protein genes, and the structures were compared among the strains. The results obtained are as follows :(1) the proteins consisted of 521-532 amino acids (corresponding to 55308-56745 dalton),(2) a putative signal peptide consisting of 22 amino acids was recognized at the N-terminal end,(3) transcription of the gene is regulated by several tandem promoters,(4) the homologies of these proteins among the six strains varied from 60 to 82% in the amino acid sequences,(5) 4 variable domains with spans of 16-40 amino acids were recognized in the molecules,(6) 56-KDa protein genes from several newly isolated strains amplified by PCR method showed polymorphism in the restriction enzyme fragment analyzes, and serotype strains of Gilliam, Karp and Kuroki strains were further classified into several subtypes.

恙虫病立克次体存在多种抗原变异，我们的前期研究表明了该立克次体的抗原类型与其对小鼠的毒力之间的关系。由于该微生物的抗原多样性是由于位于立克次体表面的56-KDa蛋白的类型特异性抗原，因此每个菌株中毒力的差异似乎取决于该蛋白的分子结构。本研究通过对Gilliam、Karp和Kato强毒株和川崎、Kuroki和Shimokoshi弱毒株56-KDa蛋白的化学分析、56-KDa蛋白基因的克隆和测序，确定了56-KDa蛋白的完整分子结构，并对不同毒株的56-KDa蛋白结构进行了比较。获得的结果如下：（1）蛋白质由521-532个氨基酸组成（对应于55308-56745道尔顿），（2）在N-末端识别由22个氨基酸组成的推定信号肽，（3）基因的转录受多个串联启动子调控，（4）这些蛋白质在6个菌株之间的氨基酸序列同源性在60%-82%之间变化，（5）分子中识别4个跨度为16-40个氨基酸的可变结构域，（6）通过PCR方法扩增的来自几个新分离菌株的56-KDa蛋白质基因在限制性酶片段分析中显示多态性，Karp和Kuroki菌株进一步分为几个亚型。