This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Armbruster, C. E. Articles by Swords, W. E. PubMed PubMed Citation Articles by Armbruster, C. E. Articles by Swords, W. E.

 Previous Article  |  Next Article 

Infection and Immunity, September 2009, p. 4081-4091, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00320-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

LuxS Promotes Biofilm Maturation and Persistence of Nontypeable Haemophilus influenzae In Vivo via Modulation of Lipooligosaccharides on the Bacterial Surface ^,

Chelsie E. Armbruster,¹ Wenzhou Hong,^1, Bing Pang,¹ Kristin E. Dew,¹ Richard A. Juneau,¹ Matthew S. Byrd,¹ Cheraton F. Love,¹ Nancy D. Kock,^2,3 and W. Edward Swords^1*

Departments of Microbiology and Immunology,¹ Pathology,² Comparative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina³

Received 19 March 2009/ Returned for modification 22 April 2009/ Accepted 22 June 2009

Nontypeable Haemophilus influenzae (NTHI) is an extremely common airway commensal which can cause opportunistic infections that are usually localized to airway mucosal surfaces. During many of these infections, NTHI forms biofilm communities that promote persistence in vivo. For many bacterial species, density-dependent quorum-signaling networks can affect biofilm formation and/or maturation. Mutation of luxS, a determinant of the autoinducer 2 (AI-2) quorum signal pathway, increases NTHI virulence in the chinchilla model for otitis media infections. For example, bacterial counts in middle-ear fluids and the severity of the host inflammatory response were increased in luxS mutants compared with parental strains. As these phenotypes are consistent with those that we have observed for biofilm-defective NTHI mutants, we hypothesized that luxS may affect NTHI biofilms. A luxS mutant was generated using the well-characterized NTHI 86-028NP strain and tested to determine the effects of the mutation on biofilm phenotypes in vitro and bacterial persistence and disease severity during experimental otitis media. Quantitation of the biofilm structure by confocal microscopy and COMSTAT analysis revealed significantly reduced biomass for NTHI 86-028NP luxS biofilms, which was restored by a soluble mediator in NTHI 86-028NP supernatants. Analysis of lipooligosaccharide moieties using an enzyme-linked immunosorbent assay and immunoblotting showed decreased levels of biofilm-associated glycoforms in the NTHI 86-028NP luxS strain. Infection studies showed that NTHI 86-028NP luxS had a significant persistence defect in vivo during chronic otitis media infection. Based on these data, we concluded that a luxS-dependent soluble mediator modulates the composition of the NTHI lipooligosaccharides, resulting in effects on biofilm maturation and bacterial persistence in vivo.

---

* Corresponding author. Mailing address: 5303 Hanes Biomedical Research Building, 1000 Medical Center Boulevard, Winston-Salem, NC 27157. Phone: (336) 713-5049. Fax: (336) 716-9928. E-mail: wswords{at}wfubmc.edu

Published ahead of print on 29 June 2009.

Supplemental material for this article may be found at http://iai.asm.org/.

Editor: J. N. Weiser

Present address: Department of Otolaryngology, Medical College of Wisconsin, Milwaukee, WI.

---

Infection and Immunity, September 2009, p. 4081-4091, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00320-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.