Novartis Vaccines and Diagnostics, Siena, Italy.
PLoS Pathog. 2011 May;7(5):e1002027. doi: 10.1371/journal.ppat.1002027. Epub 2011 May 5.
During infection Neisseria meningitidis (Nm) encounters multiple environments within the host, which makes rapid adaptation a crucial factor for meningococcal survival. Despite the importance of invasion into the bloodstream in the meningococcal disease process, little is known about how Nm adapts to permit survival and growth in blood. To address this, we performed a time-course transcriptome analysis using an ex vivo model of human whole blood infection. We observed that Nm alters the expression of ≈30% of ORFs of the genome and major dynamic changes were observed in the expression of transcriptional regulators, transport and binding proteins, energy metabolism, and surface-exposed virulence factors. In particular, we found that the gene encoding the regulator Fur, as well as all genes encoding iron uptake systems, were significantly up-regulated. Analysis of regulated genes encoding for surface-exposed proteins involved in Nm pathogenesis allowed us to better understand mechanisms used to circumvent host defenses. During blood infection, Nm activates genes encoding for the factor H binding proteins, fHbp and NspA, genes encoding for detoxifying enzymes such as SodC, Kat and AniA, as well as several less characterized surface-exposed proteins that might have a role in blood survival. Through mutagenesis studies of a subset of up-regulated genes we were able to identify new proteins important for survival in human blood and also to identify additional roles of previously known virulence factors in aiding survival in blood. Nm mutant strains lacking the genes encoding the hypothetical protein NMB1483 and the surface-exposed proteins NalP, Mip and NspA, the Fur regulator, the transferrin binding protein TbpB, and the L-lactate permease LctP were sensitive to killing by human blood. This increased knowledge of how Nm responds to adaptation in blood could also be helpful to develop diagnostic and therapeutic strategies to control the devastating disease cause by this microorganism.
在感染过程中，脑膜炎奈瑟菌（Nm）在宿主内遇到多种环境，这使得快速适应成为脑膜炎奈瑟菌生存的关键因素。尽管在脑膜炎奈瑟菌疾病过程中侵入血液至关重要，但对于脑膜炎奈瑟菌如何适应血液以允许存活和生长知之甚少。为了解决这个问题，我们使用体外全血感染模型进行了时间过程转录组分析。我们观察到，Nm 改变了基因组中约 30%的 ORF 的表达，并且在转录调节因子、运输和结合蛋白、能量代谢和表面暴露的毒力因子的表达方面观察到主要的动态变化。特别是，我们发现编码调节因子 Fur 的基因以及所有编码铁摄取系统的基因都显著上调。对编码与脑膜炎奈瑟菌发病机制相关的表面暴露蛋白的调节基因的分析使我们能够更好地理解用于规避宿主防御的机制。在血液感染期间，Nm 激活了编码因子 H 结合蛋白 fHbp 和 NspA 的基因、编码解毒酶如 SodC、Kat 和 AniA 的基因，以及一些可能在血液中生存中起作用的特征不明显的表面暴露蛋白的基因。通过对一组上调基因的突变研究，我们能够确定在人类血液中生存的新的重要蛋白质，并且还确定了以前已知的毒力因子在帮助血液中生存的其他作用。缺乏编码假定蛋白 NMB1483 和表面暴露蛋白 NalP、Mip 和 NspA、Fur 调节因子、转铁蛋白结合蛋白 TbpB 和 L-乳酸透酶 LctP 的基因的 Nm 突变株对人血的杀伤敏感。对 Nm 如何适应血液中的适应的这种增加的了解也可能有助于开发诊断和治疗策略来控制这种微生物引起的破坏性疾病。
