title: Infection rates, disease frequency, pilin gene rearrangement, and pilin expression in calves inoculated with Moraxella bovis pilin-specific isogenic variants.
abstract: Pili have been implicated as virulence factors that result in increased infectivity of Moraxella bovis, the causative agent of infectious bovine keratoconjunctivitis (IBK). Healthy calves' eyes were inoculated with I- or Q-piliate or nonpiliate M bovis Epp63 to compare the pathogenicity of these isogenic variants. Pathogenicity was determined by the rate of persistent M bovis infection and the prevalence of clinical IBK. Inoculation with M bovis expressing the Q pili resulted in the highest frequency of infection and IBK, whereas I-piliate M bovis elicited a lower rate and nonpiliate M bovis did not result in infection. In vivo pilin gene rearrangement and pilin-type switching were evaluated by DNA hybridization and immunoblot. Gene rearrangement and type switching varied dependently, and were observed only in eyes inoculated with Q-piliate M bovis. This study suggests that Q pili are specific for colonization of bovine corneal epithelium, whereas I pili enable maintenance of an established infection.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, CA 94305.
authors.forename: W W
authors.initials: WW
authors.lastname: Ruehl
authors.forename: C F
authors.initials: CF
authors.lastname: Marrs
authors.forename: L
authors.initials: L
authors.lastname: George
authors.forename: S J
authors.initials: SJ
authors.lastname: Banks
authors.forename: G K
authors.initials: GK
authors.lastname: Schoolnik
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D015321:Gene Rearrangement / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics* / Q000502:physiology; D007639:Keratoconjunctivitis, Infectious / Q000453:epidemiology / Q000382:microbiology*; D016955:Moraxella bovis / Q000235:genetics / Q000472:pathogenicity*; D016870:Neisseriaceae Infections / Q000453:epidemiology / Q000662:veterinary*; D015995:Prevalence; D014774:Virulence / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D036781:Fimbriae Proteins