LOSS OF PIGMENTATION IN SHIGELLA-FLEXNERI-2A IS CORRELATED WITH LOSS OF VIRULENCE AND VIRULENCE-ASSOCIATED PLASMID
LOSS OF PIGMENTATION IN SHIGELLA-FLEXNERI-2A IS CORRELATED WITH LOSS OF VIRULENCE AND VIRULENCE-ASSOCIATED PLASMID
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DOI：
10.1128/iai.43.1.397-401.1984
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发表时间：
1984-01-01
影响因子：
3.1
通讯作者：
CURTISS, R
中科院分区：
文献类型：
--
作者：
MAURELLI, AT;BLACKMON, B;CURTISS, R
研究了S.福氏2a菌株的能力和S.测定了福氏2a对刚果红的吸附能力。自发性非色素沉着（即，不能结合刚果红[Pcr-]）衍生物。分离弗氏2a，并通过它们侵入上皮细胞的能力测定毒力。所有检查的Per突变体都失去了侵入上皮细胞的能力，因此是无毒的。这些无毒力的Pcr-突变体的质粒DNA的琼脂糖凝胶电泳显示，这些菌株中的大多数已经失去了对应于毒力相关质粒pSf 2a 140的质粒条带。在许多突变体中，色素沉着、毒力和pSf 2a 140的伴随损失伴随着比pSf 2a 140小的新质粒的出现。这些新质粒可能是pSf 2a 140的缺失衍生物;色素沉着和毒力的丧失可能与pSf 2a 140中的缺失有关。将Pcr-突变体转导为Pcr+;分离抑制Pcr-表型的转导子。没有一个Pcr+转导子重新获得侵入上皮细胞的能力。Pcr-表型的几个抑制子被鉴定为细胞壁生物合成中的突变。虽然色素沉着通常与毒力有关，但与毒力无关的遗传决定因素也可能影响细胞结合刚果红的能力。因此，S.福氏2a结合刚果红的能力不一定意味着侵袭上皮细胞的能力;结合刚果红的能力的丧失伴随着毒力的丧失。
The relationship between the virulence of S. flexneri 2a and the ability of strains of S. flexneri 2a to absorb Congo red was examined. Spontaneous nonpigmented (i.e., unable to bind Congo red [Pcr-]) derivatives of a virulent, pigmented (Pcr+) strain of S. flexneri 2a were isolated and assayed for virulence as determined by their ability to invade epithelial cells. All Per- mutants examined lost the ability to invade epithelial cells and were thus avirulent. Agarose gel electrophoresis of plasmid DNA from these avirulent, Pcr- mutants showed that the majority of these strains had lost a plasmid band corresponding to a virulence-associated plasmid, pSf2a140. In many of the mutants, concomitant loss of pigmentation, virulence and pSf2a140 was accompanied by the appearance of a new plasmid, smaller than pSf2a140. These new plasmids may be deletion derivatives of pSf2a140; loss of pigmentation and virulence may be associated with deletions in pSf2a140. Pcr- mutants were transduced to Pcr+; transductants which suppressed the Pcr- phenotype were isolated. None of the Pcr+ transductants regained the ability to invade epithelial cells. Several suppressors of the Pcr- phenotype were identified as mutations in cell wall biosynthesis. Although pigmentation is usually associated with virulence, genetic determinants unrelated to virulence may also affect the ability of the cell to bind Congo red. Therefore, the ability of S. flexneri 2a to bind Congo red does not necessarily imply the ability to invade epithelial cells; loss of ability to bind Congo red is accompanied by loss of virulence.