Moshitch S, Doll L, Rubinfeld B Z, Stocker B A, Schoolnik G K, Gafni Y, Frankel G
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Mol Microbiol. 1992 Sep;6(18):2589-97. doi: 10.1111/j.1365-2958.1992.tb01436.x.
Several lines of evidence indicate a relatively low genetic heterogeneity in the natural Salmonella typhi population. However, some S. typhi isolates found in Indonesia express, instead of the usual fliC-d flagellin gene, a different flagellar gene fliC-j. In addition, Indonesian strains may have a second flagellar antigen fliC-z66. We have previously suggested, on the basis of the flagellar antigen constitution, that S. typhi evolved in an isolated human population in Indonesia. In order to test this hypothesis, we have gathered S. typhi isolates from around the world and tested the genetic heterogeneity among them. In general, polymorphism was greater in isolates from the Far East, as was indicated by Southern hybridizations with rDNA and fliC DNA probes. Gene fliC-j was not found in S. typhi isolates, other than those from Indonesia. However, the one-clone origin of S. typhi was indicated by a common DNA fingerprint pattern and by the occurrence, in the 5' end region of the fliC gene, of 10 scattered nucleotides that differ from the corresponding 10 nucleotides in other fliC alleles studied. These nucleotides were present in all isolates tested but did not change the amino acid sequence of the flagellin polypeptide.
多项证据表明，伤寒沙门氏菌自然种群中的遗传异质性相对较低。然而，在印度尼西亚发现的一些伤寒沙门氏菌分离株表达的不是常见的fliC-d鞭毛蛋白基因，而是一种不同的鞭毛基因fliC-j。此外，印度尼西亚菌株可能还有第二种鞭毛抗原fliC-z66。我们之前曾基于鞭毛抗原构成提出，伤寒沙门氏菌是在印度尼西亚一个与世隔绝的人群中进化而来的。为了验证这一假设，我们收集了来自世界各地的伤寒沙门氏菌分离株，并测试了它们之间的遗传异质性。总体而言，如用rDNA和fliC DNA探针进行的Southern杂交所示，来自远东地区的分离株中的多态性更大。除了来自印度尼西亚的分离株外，在其他伤寒沙门氏菌分离株中未发现fliC-j基因。然而，一种常见的DNA指纹图谱以及在fliC基因5'端区域出现的10个分散核苷酸（与所研究的其他fliC等位基因中的相应10个核苷酸不同）表明伤寒沙门氏菌起源于单一克隆。这些核苷酸存在于所有测试的分离株中，但并未改变鞭毛蛋白多肽的氨基酸序列。
