International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
PLoS Negl Trop Dis. 2011 Dec;5(12):e1419. doi: 10.1371/journal.pntd.0001419. Epub 2011 Dec 13.
Salmonella enterica serotype Typhi is the cause of typhoid fever. It is a human-restricted pathogen, and few data exist on S. Typhi gene expression in humans.
METHODOLOGY/PRINCIPAL FINDINGS: We applied an RNA capture and amplification technique, Selective Capture of Transcribed Sequences (SCOTS), and microarray hybridization to identify S. Typhi transcripts expressed in the blood of five humans infected with S. Typhi in Bangladesh. In total, we detected the expression of mRNAs for 2,046 S. Typhi genes (44% of the S. Typhi genome) in human blood; expression of 912 genes was detected in all 5 patients, and expression of 1,100 genes was detected in 4 or more patients. Identified transcripts were associated with the virulence-associated PhoP regulon, Salmonella pathogenicity islands, the use of alternative carbon and energy sources, synthesis and transport of iron, thiamine, and biotin, and resistance to antimicrobial peptides and oxidative stress. The most highly represented group were genes currently annotated as encoding proteins designated as hypothetical, unknown, or unclassified. Of the 2,046 detected transcripts, 1,320 (29% of the S. Typhi genome) had significantly different levels of detection in human blood compared to in vitro cultures; detection of 141 transcripts was significantly different in all 5 patients, and detection of 331 transcripts varied in at least 4 patients. These mRNAs encode proteins of unknown function, those involved in energy metabolism, transport and binding, cell envelope, cellular processes, and pathogenesis. We confirmed increased expression of a subset of identified mRNAs by quantitative-PCR.
CONCLUSIONS/SIGNIFICANCE: We report the first characterization of bacterial transcriptional profiles in the blood of patients with typhoid fever. S. Typhi is an important global pathogen whose restricted host range has greatly inhibited laboratory studies. Our results suggest that S. Typhi uses a largely uncharacterized genetic repertoire to survive within cells and utilize alternate energy sources during infection.
肠伤寒沙门氏菌血清型 Typhi 是伤寒的病原体。它是一种人类局限性病原体，关于 S. Typhi 在人类中的基因表达的数据很少。
方法/主要发现：我们应用了一种 RNA 捕获和扩增技术，即转录序列的选择性捕获（SCOTS）和微阵列杂交，以鉴定孟加拉国 5 名感染 S. Typhi 的人类血液中的 S. Typhi 转录本。总共，我们在人类血液中检测到了 2046 个 S. Typhi 基因的 mRNA 表达（S. Typhi 基因组的 44%）；在所有 5 名患者中均检测到 912 个基因的表达，在 4 名或更多患者中检测到 1100 个基因的表达。鉴定出的转录本与毒力相关的 PhoP 调节子、沙门氏菌致病岛、替代碳和能源的利用、铁、硫胺素和生物素的合成和运输以及对抗抗菌肽和氧化应激有关。代表性最强的一组是目前被注释为编码假定、未知或未分类蛋白质的基因。在检测到的 2046 个转录本中，与体外培养相比，在人类血液中检测到的 1320 个（S. Typhi 基因组的 29%）的水平有显著差异；在所有 5 名患者中，141 个转录本的检测均有显著差异，而至少有 4 名患者中 331 个转录本的检测有差异。这些 mRNA 编码未知功能的蛋白质、参与能量代谢、运输和结合、细胞包膜、细胞过程和发病机制的蛋白质。我们通过定量-PCR 证实了一部分鉴定出的 mRNA 的表达增加。
结论/意义：我们报告了首次在伤寒患者血液中描述细菌转录谱。S. Typhi 是一种重要的全球病原体，其受限的宿主范围极大地抑制了实验室研究。我们的结果表明，S. Typhi 利用一个很大程度上未被描述的遗传资源库，在感染期间在细胞内生存并利用替代能源。
