Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA.
J Infect Dis. 2013 Sep 1;208(5):720-7. doi: 10.1093/infdis/jit240. Epub 2013 May 28.
Studies of nontypeable Haemophilus influenzae (NTHi) have demonstrated that a number of genes associated with infectivity have long repeat regions associated with phase variation in expression of the respective gene. The purpose of this study was to determine the genes that underwent phase variation during a 6-day period of experimental human nasopharyngeal colonization.
Strain NTHi 2019Str(R)1 was used to colonize the nasopharynx of human subjects in a study of experimental colonization. Thirteen phase-variable genes were analyzed in NTHi 2019Str(R)1. Samples of NTHi 2019Str(R)1 were cultured from subjects during the 6-day colonization period. We used capillary electrophoresis and Roche 454 pyrosequencing to determine the number of repeats in each gene from each sample.
A significant number of samples switched licA and igaB from phase off in the inoculated strain to phase on during the 4-day period of observation. lex2A also showed variability as compared to baseline, but the differences were not significant. The remaining genes showed no evidence of phase variation.
Our studies suggest that the phase-on genotypes of licA and igaB are important for early human nasopharynx colonization. lex2A showed a trend from phase off to phase on, suggesting a potentially important role in the colonization process.
研究表明，许多与传染性相关的基因在非定型流感嗜血杆菌（NTHi）中存在长重复区域，这些区域与相应基因表达的相变异有关。本研究旨在确定在实验性人类鼻咽定植的 6 天期间经历相变异的基因。
使用 NTHi 2019Str(R)1 菌株在实验性定植研究中定植人类受试者的鼻咽。分析了 NTHi 2019Str(R)1 中的 13 个相变异基因。在 6 天定植期间，从受试者中培养 NTHi 2019Str(R)1 样本。我们使用毛细管电泳和 Roche 454 焦磷酸测序来确定每个样本中每个基因的重复次数。
在观察的 4 天期间，大量样本将 licA 和 igaB 从接种菌株的相关闭状态切换为相开启状态。lex2A 与基线相比也表现出可变性，但差异不显著。其余基因没有表现出相变异的证据。
我们的研究表明，licA 和 igaB 的相开启基因型对于早期人类鼻咽定植很重要。lex2A 显示出从相关闭到相开启的趋势，这表明它在定植过程中可能具有重要作用。
