title: Prevalence, distribution, and sequence diversity of hmwA among commensal and otitis media non-typeable Haemophilus influenzae.
abstract: Nontypeable Haemophilus influenzae (NTHi) are Gram-negative coccobacilli that colonize the human pharynx, their only known natural reservoir. Adherence to the host epithelium facilitates NTHi colonization and marks one of the first steps in NTHi pathogenesis. Epithelial cell attachment is mediated, in part, by a pair of high molecular weight (HMW) adhesins that are highly immunogenic, antigenically diverse, and display a wide range of amino acid diversity both within and between isolates. In this study, the prevalence of hmwA, which encodes the HMW adhesin, was determined for a collection of 170 NTHi isolates recovered from the middle ears of children with otitis media (OM isolates) or throats or nasopharynges of healthy children (commensal isolates) from Finland, Israel, and the U.S. Overall, hmwA was detected in 61% of NTHi isolates and was significantly more prevalent (P=0.004) among OM isolates than among commensal isolates; the prevalence ratio comparing hmwA prevalence among ear isolates with that of commensal isolates was 1.47 (95% CI (1.12, 1.92)). Ninety-five percent (98/103) of the hmwA-positive NTHi isolates possessed two hmw loci. To advance our understanding of hmwA binding sequence diversity, we determined the DNA sequence of the hmwA binding region of 33 isolates from this collection. The average amino acid identity across all hmwA sequences was 62%. Phylogenetic analyses of the hmwA binding revealed four distinct sequence clusters, and the majority of hmwA sequences (83%) belonged to one of two dominant sequence clusters. hmwA sequences did not cluster by chromosomal location, geographic region, or disease status.
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA. Electronic address: gsdavis@gwu.edu.
authors.forename: Gregg S
authors.initials: GS
authors.lastname: Davis
authors.affiliation: Department of Pediatrics, University of Michigan Medical School, D5101 Medical Professional Building, Ann Arbor, MI 48109-5718, USA. Electronic address: mpatel@umich.edu.
authors.forename: May
authors.initials: M
authors.lastname: Patel
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA. Electronic address: jamhenha@gmail.com.
authors.forename: James
authors.initials: J
authors.lastname: Hammond
authors.affiliation: Department of Epidemiology and Biostatistics, Michigan State University, 909 Fee Road Room B601, East Lansing, MI 48824, USA.. Electronic address: lxzhang@msu.edu.
authors.forename: Lixin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, University of Michigan Medical School, D5101 Medical Professional Building, Ann Arbor, MI 48109-5718, USA; Department of Microbiology and Immunology, University of Michigan Medical School, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA. Electronic address: sdawid@umich.edu.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Dawid
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA. Electronic address: cfmarrs@umich.edu.
authors.forename: Carl F
authors.initials: CF
authors.lastname: Marrs
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA; Department of Pediatrics, University of Michigan Medical School, D5101 Medical Professional Building, Ann Arbor, MI 48109-5718, USA. Electronic address: gilsdorf@med.umich.edu.
authors.forename: Janet R
authors.initials: JR
authors.lastname: Gilsdorf
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D002648:Child; D002675:Child, Preschool; D019143:Evolution, Molecular; D005387:Finland; D014644:Genetic Variation; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007557:Israel; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000382:microbiology*; D010614:Pharynx / Q000382:microbiology*; D010802:Phylogeny; D014481:United States
chemical_list: D018829:Adhesins, Bacterial
keywords: Acute otitis media; Adherence; Evolution; High molecular weight adhesins; NTHi; Phylogenetics