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首页> 外文期刊>Infection and immunity >Role of Shiga toxin in the pathogenesis of bacillary dysentery, studied by using a Tox- mutant of Shigella dysenteriae 1.
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Role of Shiga toxin in the pathogenesis of bacillary dysentery, studied by using a Tox- mutant of Shigella dysenteriae 1.

机译:志贺毒素在细菌性痢疾发病机理中的作用,通过痢疾志贺氏菌1的Tox突变体进行了研究。

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摘要

A Tox- mutant of Shigella dysenteriae 1, SC501, was genetically engineered by cloning the Shiga toxin operon, inserting a cassette into the A subunit gene, and exchanging this in vitro-mutagenized sequence with the wild-type gene. SC501 produced a low amount of residual cytotoxicity which was not neutralized by a rabbit immune serum directed against Shiga toxin. Invasion of cultured cells demonstrated that Shiga toxin had no effect on the rate of intracellular growth of bacteria or on the rapid killing of invaded host cells. On the other hand, several significant differences were observed in macaque monkeys infected intragastrically with either the wild-type strain or its mutant. The production of Shiga toxin by the invading strain was correlated with the presence of blood within stools, a sharp drop in blood polymorphonuclear cells, and histopathological alterations, such as the destruction of capillary vessels within the connective tissue of the colonic mucosa, severe inflammatory vasculitis of the peritoneal mesothelium, and major efflux of inflammatory cells to the intestinal lumen. It is proposed that Shiga toxin influences the severity of bacillary dysentery by inducing colonic vascular damage, which accounts for bloody stools, intestinal ischemia, and inflation of a polymorphonuclear intestinal compartment during the infectious process.
机译:痢疾志贺氏菌1(SC501)的Tox突变体是通过克隆志贺毒素操纵子,将一个盒体插入A亚基基因,然后将这种体外诱变的序列与野生型基因交换而进行遗传工程改造的。 SC501产生的残留细胞毒性很低,而针对志贺毒素的兔免疫血清并未中和。对培养细胞的入侵表明,志贺毒素对细菌的细胞内生长速率或入侵宿主细胞的快速杀灭均无影响。另一方面,在用野生型菌株或其突变体在胃内感染的猕猴中观察到一些显着差异。侵染菌株产生志贺毒素与粪便中血液的存在,血液中多形核细胞的急剧下降以及组织病理学改变有关,例如结肠粘膜结缔组织内毛细血管的破坏,严重的炎性血管炎腹膜间皮细胞的炎症,以及炎症细胞向肠腔的主要外流。有人提出,志贺毒素可通过诱导结肠血管损伤来影响细菌性痢疾的严重程度,结肠损伤是造成血便,肠道缺血和感染过程中多形核肠腔膨胀的原因。

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