title: The role of the RNA chaperone Hfq in Haemophilus influenzae pathogenesis.
abstract: BACKGROUND
  The RNA binding protein Hfq of Haemophilus influenzae is highly homologous to Hfq from other bacterial species. In many of these other bacteria, Hfq affects the expression of a broad range of genes and enhances the ability to respond to stressful environments. However, the role of Hfq in H. influenzae is unknown.
  
  
  RESULTS
  Deletion mutants of hfq were generated in the nontypeable H. influenzae strains R2866 and 86-028NP to assess the role of Hfq in these well characterized but genotypically and phenotypically divergent clinical isolates. A deletion mutation of hfq had no effect on growth of H. influenzae in nutrient rich media and had no effect on survival in several stressful conditions in vitro. However, the mutation resulted in a reduced ability to utilize heme from hemoglobin. The mutant and wild type strains were assessed for virulence and competitive fitness in models of invasive disease and otitis media. In the chinchilla model of otitis media, the hfq mutant of 86-028NP exhibited impaired competitive fitness when compared to its wild type progenitor but exhibited no apparent defect in virulence. In the infant rat model, deletion of hfq in R2866 resulted in reduced bacterial titers in blood and a shorter duration of infection when compared to the wild type strain in the competitive fitness study.
  
  
  CONCLUSIONS
  We conclude that Hfq is involved in the utilization of essential nutrients and facilitates infection by H. influenzae.
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Hempel
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Morton
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Seale
authors.forename: Paul W
authors.initials: PW
authors.lastname: Whitby
authors.forename: Terrence L
authors.initials: TL
authors.lastname: Stull
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D016470:Bacteremia / Q000382:microbiology / Q000473:pathology; D058491:Bacterial Load; D002682:Chinchilla; D005260:Female; D017353:Gene Deletion; D006192:Haemophilus Infections / Q000382:microbiology / Q000473:pathology; D006193:Haemophilus influenzae / Q000235:genetics / Q000472:pathogenicity*; D006418:Heme / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D035001:Host Factor 1 Protein / Q000235:genetics / Q000378:metabolism*; D010033:Otitis Media / Q000382:microbiology / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D006454:Hemoglobins; D035001:Host Factor 1 Protein; D037521:Virulence Factors; D006418:Heme