Identification of Streptococcus agalactiae virulence genes in the neonatal rat sepsis model using signature-tagged mutagenesis
Identification of Streptococcus agalactiae virulence genes in the neonatal rat sepsis model using signature-tagged mutagenesis
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DOI：
10.1046/j.1365-2958.2000.02099.x
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发表时间：
2000-09-01
影响因子：
3.6
通讯作者：
Rubens, CE
中科院分区：
文献类型：
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作者：
Jones, AL;Knoll, KM;Rubens, CE
B族链球菌（GBS）感染是新生儿期细菌性败血症的最常见原因。除了胶囊，GBS在宿主中存活所需的因素还没有很好的定义。在这项研究中，签名标记的转座子诱变（STM）被用来确定GBS的生长和生存所需的基因在新生大鼠败血症感染模型。在80个突变体的库中筛选了大约1600个转座子突变体，并且鉴定了大约120个在动物宿主中存活缺陷的突变体。我们成功地克隆和测序了92个突变体的转座子插入侧翼DNA。50%的突变体在公共数据库中具有同源基因的基因中插入转座子，而其余50%的突变体在功能未知的基因中插入转座子。一个显着比例的无毒突变体的转座子插入编码转运相关或调节蛋白的基因或参与细胞表面代谢的基因，强调这些功能的GBS在体内生存的意义。总体而言，STM分析揭示了GBS基因组位点编码各种各样的功能基因类，强调了感染过程所需的细菌过程的多样性。目前，在筛选期间鉴定的基因的功能只能通过与先前描述的基因的同源性来推断。然而，在这项研究中发现的一些基因已被证明与其他病原体的毒力相关。通过进行竞争指数测定和致死剂量测定，确认了筛选期间鉴定的突变体亚组的无毒力。这是第一次报告的全基因组扫描GBS的毒力因子。这些基因将进一步加深我们对GBS感染发病机制的理解，并可能成为干预的靶点或导致新疗法的开发。
Group B streptococcal (GBS) infections are the most common cause of bacterial sepsis in the immediate newborn period. Apart from the capsule, the factors required for survival of GBS in the host are not well defined. In this study, signature-tagged transposon mutagenesis (STM) was used to identify genes required for growth and survival of GBS in a neonatal rat sepsis infection model. Approximately 1600 transposon mutants were screened in pools of 80 mutants, and approximately 120 mutants defective for survival in the animal host were identified. We successfully cloned and sequenced DNA flanking the transposon insertions from 92 of the mutants. Fifty per cent of the mutants had transposon insertions in genes with homologues in the public databases, whereas the remaining 50% had transposon insertions in genes with unknown function. A significant proportion of the avirulent mutants had transposon insertions in genes encoding transport-associated or regulatory proteins or in genes involved in cell surface metabolism, emphasizing the significance of these functions for in vivo survival of GBS. Overall, STM analysis revealed GBS genomic loci that encode a wide variety of functional gene classes, underscoring the diversity of bacterial processes required for the infection process. Currently, the function of the genes identified during the screening can only be inferred by homology to previously described genes. However, a number of the genes identified in this study have been shown to correlate with virulence in other pathogens. Avirulence of a subset of mutants identified during the screening was confirmed by performing competitive index assays and lethal dose assays. This represents the first report of a genome-wide scan for virulence factors in GBS. The identified genes will further our understanding of the pathogenesis of GBS infections and may represent targets for intervention or lead to the development of novel therapies.