Sansonetti P J, d'Hauteville H, Ecobichon C, Pourcel C
Ann Microbiol (Paris). 1983 May-Jun;134A(3):295-318.
Virulent isolates of Shigella dysenteriae and Shigella boydii harboured a 140 Mdal plasmid which was either absent or deleted in spontaneously avirulent strains. Together with previous data concerning S. sonnei, S. flexneri and enteroinvasive Escherichia coli, the present results established the general role of extrachromosomal elements in the virulence of such enteroinvasive species. Among different species, these virulence plasmids showed unrelated endonuclease cleavage patterns, whereas hybridization experiments showed that homologous sequences were present throughout the molecules. These plasmids may therefore have derived from a common ancestor molecule which overcame evolutionary alterations in restriction sites. Furthermore, intraspecies and intraserotype comparison of these plasmids by endonuclease cleavage demonstrated highly conserved sequences. The consequences of these data for evolution, epidemiology and diagnosis of Shigella and enteroinvasive E. coli are discussed.
痢疾志贺氏菌和鲍氏志贺氏菌的强毒株含有一个140兆道尔顿的质粒，而在自发无毒株中该质粒要么不存在，要么已缺失。结合先前有关宋内志贺氏菌、福氏志贺氏菌和侵袭性大肠杆菌的数据，目前的结果确立了染色体外元件在这类侵袭性肠道菌毒力中的普遍作用。在不同菌种中，这些毒力质粒显示出不相关的核酸内切酶切割模式，而杂交实验表明整个分子中都存在同源序列。因此，这些质粒可能源自一个共同的祖先分子，该分子克服了限制位点的进化改变。此外，通过核酸内切酶切割对这些质粒进行种内和血清型内比较，结果显示序列高度保守。本文讨论了这些数据对志贺氏菌和侵袭性大肠杆菌的进化、流行病学及诊断的影响。
