Non-encapsulated strains reveal novel insights in invasion and survival of Streptococcus suis in epithelial cells
Non-encapsulated strains reveal novel insights in invasion and survival of Streptococcus suis in epithelial cells
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DOI：
10.1111/j.1462-5822.2004.00409.x
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发表时间：
2004-09-01
影响因子：
3.4
通讯作者：
Valentin-Weigand, P
中科院分区：
文献类型：
--
作者：
Benga, L;Goethe, R;Valentin-Weigand, P
猪链球菌是一种猪和人类的病原体，会引起脑膜炎或败血症等侵袭性疾病。目前主要研究猪链球菌与2型毒株的宿主细胞相互作用，但存在多种衣壳血清型和非分型株，毒力特征各异。目前，猪链球菌被认为是一种胞外病原体。然而，它是否也能入侵宿主细胞是一个有争议的讨论问题。我们通过比较10株2型血清株和4株非分型(NT)株，评估了猪链球菌对Hep-2上皮细胞的黏附和侵袭能力。只有NT株和一株非包膜的2型突变株具有较强的粘附性和侵袭性，而2型株均未见。从不同培养基中生长的菌株的比较可以看出，入侵似乎受到环境信号的影响。进一步的表型和基因特征分析表明，不同菌株之间具有高度的多样性。对选定的侵袭性NT菌株的侵袭进行了电子显微镜分析，显示了不同的摄取机制。一个菌株诱导了与‘小窝’介导的摄取类似的大内陷，而另一个菌株的入侵伴随着丝足状膜突起的形成。然而，所有菌株的侵袭都同样对高渗蔗糖敏感，高渗蔗糖抑制受体介导的内吞作用。与摄取途径无关，链球菌驻留在酸化的吞噬溶酶体样空泡中。除一株外，所有菌株均能在胞内和胞外酸性条件下存活。存活似乎与Adis蛋白有关，Adis蛋白是猪链球菌的一种环境调节的精氨酸脱亚胺酶。结论是，NT株猪链球菌在上皮细胞中的侵袭和存活揭示了新的证据，即猪链球菌表现出广泛的毒力相关特征，这取决于遗传变异和调控。
Streptococcus suis is a porcine and human pathogen causing invasive diseases, such as meningitis or septicaemia. Host cell interactions of S. suis have been studied mainly with serotype 2 strains, but multiple capsular serotypes as well as non-typeable strains exist with diverse virulence features. At present, S. suis is considered an extracellular pathogen. However, whether or not it can also invade host cells is a matter of controversial discussions. We have assessed adherence and invasion of S. suis for HEp-2 epithelial cells by comparing 10 serotype 2 strains and four non-typeable (NT) strains. Only the NT strains and a non-encapsulated serotype 2 mutant strain, but none of the serotype 2 strains, adhered strongly and were invasive. Invasion seemed to be affected by environmental signals, as suggested from comparison of strains grown in different media. Further phenotypic and genotypic characterization revealed a high diversity among the different strains. Electron microscopic analysis of invasion of selected invasive NT strains indicated different uptake mechanisms. One strain induced large invaginations comparable to those seen in 'caveolae' mediated uptake, whereas invasion of the other strains was accompanied by formation of filipodia-like membrane protrusions. Invasion of all strains, however, was similarly susceptible to hypertonic sucrose, which inhibits receptor-mediated endocytosis. Irrespective of the uptake pathway, streptococci resided in acidified phago-lysosome like vacuoles. All strains, except one, survived intracellularly as well as extracellular acidic conditions. Survival seemed to be associated with the AdiS protein, an environmentally regulated arginine deiminase of S. suis. Concluding, invasion and survival of NT strains of S. suis in epithelial cells revealed novel evidence that S. suis exhibits a broad variety of virulence-associated features depending on genetic variation and regulation.