Intracellular multiplication and virulence of Shigella flexneri auxotrophic mutants
Intracellular multiplication and virulence of Shigella flexneri auxotrophic mutants
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DOI：
10.1128/iai.66.2.549-557.1998
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发表时间：
1998-02-01
影响因子：
3.1
通讯作者：
Bernardini, ML
中科院分区：
文献类型：
--
作者：
Cersini, A;Salvia, AM;Bernardini, ML
我们构建并分析了一组福氏志贺菌5营养缺陷型突变株。野生型菌株M90 T在编码参与（i）芳香族氨基酸、（ii）核苷酸和（iii）二氨基庚二酸合成的酶的基因中被诱变。（aroB、aroC、aroD、purE、thyA和dapB）和double（purE aroB、purE aroC、purE aroD、purE thyA）突变。虽然Aro突变体在实验室培养基中生长时具有相同的营养需求，aroB突变株的致病力不明显，而aroC和aroD突变株的致病力都很强，对氨基苯甲酸（PABA）是Aro突变株在组织培养中生长的主要条件。然而，当与另一种影响毒力的突变组合时，腺嘌呤营养缺陷型似乎加强了该突变的作用。因此，如通过Sereny测试所测量的，purE和aroC或purE和aroD突变的关联对毒力具有很大的影响，而purE aroB双突变似乎仅具有很小的影响，除dapB菌株外的所有突变体似乎在感染3小时后在Caco-2细胞单层内移动。然而，显示高细胞内产生时间的营养缺陷型在空斑测定中是阴性的，了解每个突变在减毒志贺菌菌株中的作用将为设计候选疫苗提供有用的工具。
We have constructed and analyzed a group of Shigella flexneri 5 auxotrophic mutants, The wild-type strain M90T was mutagenized in genes encoding enzymes involved in the synthesis of (i) aromatic amino acids, (ii) nucleotides, and (iii) diaminopimelic acid, In this way, strains with single (aroB, aroC, aroD, purE, thyA, and dapB) and double (purE aroB, purE aroC, purE aroD, purE thyA) mutations were obtained, Although the Aro mutants had the same nutritional requirements when grown in laboratory media, they showed different degrees of virulence in vitro and in vivo, The aroB mutant was not significantly attenuated, whereas both the aroC and aroD strains were severely attenuated, p-Aminobenzoic acid (PABA) appeared to be the main requirement for the Aro mutants' growth in tissue culture, Concerning nucleotides, thymine reduced the pathogenicity, whereas adenine did not. However, when combined with another virulence-affecting mutation, adenine auxotrophy appeared to potentiate that mutation's effects, Consequently, the association of either the purE and aroC or the purE and aroD mutations had a great effect on virulence as measured by the Sereny test, whereas the purE aroB double mutation appeared to have only a small effect, All mutants except the dapB strain seemed to move within a Caco-2 cell monolayer after 3 h of infection, Nevertheless, the auxotrophs showing a high intracellular generation time were negative in the plaque assay, Knowledge of each mutation's role in attenuating Shigella strains will provide useful tools in designing vaccine candidates.