Type 1 fimbriae of Salmonella enterica serovar typhimurium bind to enterocytes and contribute to colonization of swine in vivo
Type 1 fimbriae of Salmonella enterica serovar typhimurium bind to enterocytes and contribute to colonization of swine in vivo
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DOI：
10.1128/iai.71.11.6446-6452.2003
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发表时间：
2003-11-01
影响因子：
3.1
通讯作者：
Isaacson, RE
中科院分区：
文献类型：
--
作者：
Althouse, C;Patterson, S;Isaacson, RE
肠沙门氏菌鼠伤寒血清型 798 株是从猪中分离出来的临床菌株，已知能够引起持续性无症状感染。还已知该菌株存在两种表型（对肠细胞粘附和非粘附），并且可以以与相位变化一致的速率在两种表型之间切换。粘附表型的细胞比非粘附细胞更容易被白细胞吞噬。一旦进入白细胞，粘附相细胞就会存活，而非粘附相细胞就会死亡。在本研究中，利用转座子 TnphoA 获得了非粘附突变体。选择非粘附突变体进行研究，并通过电子显微镜显示不产生菌毛。克隆编码粘附素的基因并测序。根据其序列，粘附素被证明是 FimA，1 型菌毛的主要亚基。非粘附突变体在小鼠和猪肠道中定殖的能力减弱，但仍然能够在小鼠中全身传播。非粘附突变体在粘附期被吞噬至与亲本细胞相同的程度，然后在细胞内存活。这些结果表明，I 型菌毛对于肠细胞的附着和促进肠道定植非常重要。然而，它们对于促进吞噬作用或细胞内存活并不重要。
Salmonella enterica serovar Typhimurium strain 798 is a clinical isolate from a pig and is known to be able to cause persistent, asymptomatic infections. This strain also is known to exist in two phenotypes (adhesive and nonadhesive to enterocytes) and can switch between the two phenotypes at a rate consistent with phase variation. Cells in the adhesive phenotype are more readily phagocytosed by leukocytes than nonadhesive cells. Once in a leukocyte, adhesive-phase cells survive while nonadhesive-phase cells die. In the present study, nonadhesive mutants were obtained with the transposon TnphoA. A nonadhesive mutant was selected for study and was shown by electron microscopy not to produce fimbriae. The gene encoding the adhesin was cloned and sequenced. Based on its sequence, the adhesin was shown to be FimA, the major subunit of type 1 fimbriae. The nonadhesive mutant was attenuated in its ability to colonize both mouse and pig intestines, but remained capable of systemic spread in mice. The nonadhesive mutant was phagocytosed to the same extent as parental cells in the adhesive phase and then survived intracellularly. These results demonstrated that type I fimbriae were important for attachment to enterocytes and promoted intestinal colonization. However, they were not important in promoting phagocytosis or intracellular survival.