title: Nontypeable Haemophilus influenzae genetic islands associated with chronic pulmonary infection.
abstract: BACKGROUND
  Haemophilus influenzae (Hi) colonizes the human respiratory tract and is an important pathogen associated with chronic obstructive pulmonary disease (COPD). Bacterial factors that interact with the human host may be important in the pathogenesis of COPD. These factors, however, have not been well defined. The overall goal of this study was to identify bacterial genetic elements with increased prevalence among H. influenzae strains isolated from patients with COPD compared to those isolated from the pharynges of healthy individuals.
  
  
  RESULTS
  Four nontypeable H. influenzae (NTHi) strains, two isolated from the airways of patients with COPD and two from a healthy individual, were subjected to whole genome sequencing using 454 FLX Titanium technology. COPD strain-specific genetic islands greater than 500 bp in size were identified by in silico subtraction. Open reading frames residing within these islands include known Hi virulence genes such as lic2b, hgbA, iga, hmw1 and hmw2, as well as genes encoding urease and other enzymes involving metabolic pathways. The distributions of seven selected genetic islands were assessed among a panel of 421 NTHi strains of both disease and commensal origins using a Library-on-a-Slide high throughput dot blot DNA hybridization procedure. Four of the seven islands screened, containing genes that encode a methyltransferase, a dehydrogenase, a urease synthesis enzyme, and a set of unknown short ORFs, respectively, were more prevalent in COPD strains than in colonizing strains with prevalence ratios ranging from 1.21 to 2.85 (p ≤ 0.0002). Surprisingly, none of these sequences show increased prevalence among NTHi isolated from the airways of patients with cystic fibrosis.
  
  
  CONCLUSIONS
  Our data suggest that specific bacterial genes, many involved in metabolic functions, are associated with the ability of NTHi strains to survive in the lower airways of patients with COPD.
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, Michigan, United States of America. lxzhang@umich.edu
authors.forename: Lixin
authors.initials: L
authors.lastname: Zhang
authors.forename: Jingping
authors.initials: J
authors.lastname: Xie
authors.forename: Mayuri
authors.initials: M
authors.lastname: Patel
authors.forename: Arsala
authors.initials: A
authors.lastname: Bakhtyar
authors.forename: Garth D
authors.initials: GD
authors.lastname: Ehrlich
authors.forename: Azad
authors.initials: A
authors.lastname: Ahmed
authors.forename: Josh
authors.initials: J
authors.lastname: Earl
authors.forename: Carl F
authors.initials: CF
authors.lastname: Marrs
authors.forename: Daniel
authors.initials: D
authors.lastname: Clemans
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Murphy
authors.forename: Janet R
authors.initials: JR
authors.lastname: Gilsdorf
mesh_terms: D015139:Blotting, Southern; D016022:Case-Control Studies; D002908:Chronic Disease; D005798:Genes, Bacterial; D020022:Genetic Predisposition to Disease; D006193:Haemophilus influenzae / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D029424:Pulmonary Disease, Chronic Obstructive / Q000235:genetics*; D014774:Virulence / Q000235:genetics