title: Oral inoculation of young dairy calves with Mycoplasma bovis results in colonization of tonsils, development of otitis media and local immunity.
abstract: Because M. bovis otitis media is an economically important problem, there is a need to understand the pathogenesis of disease, not only to improve our understanding of the factors contributing to the development of this disease but also to inform the development of improved diagnostic tests and therapy. Oral ingestion of M. bovis-contaminated milk is linked, but not definitively proven, to development of otitis media. In the current study, we demonstrate that oral ingestion of M. bovis infected colostrum can result in an ascending infection and development of otitis media. Importantly, M. bovis was found to have a previously unrecognized tendency for colonization of the tonsils of calves, which most likely contributed to the subsequent development of otitis media. In contrast, transtracheal inoculation failed to produce clinically significant upper respiratory tract disease, although did induce lower respiratory tract disease. The upper respiratory tract was the major site of M. bovis-specific B cell and mucosal IgA responses in calves inoculated by the oral route. The oral inoculation route of infection presented here is particularly suited to the study of host-pathogen interactions during initial colonization of the tonsils, expansion of infection and dissemination to the lower respiratory tract and middle ear. In addition, it could be used to investigate potential new preventative or control strategies, especially those aimed at limiting colonization of the tonsils and/or spread to the middle ear.
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Fiona
authors.initials: F
authors.lastname: Maunsell
authors.forename: Mary B
authors.initials: MB
authors.lastname: Brown
authors.forename: Joshua
authors.initials: J
authors.lastname: Powe
authors.forename: James
authors.initials: J
authors.lastname: Ivey
authors.forename: Matthew
authors.initials: M
authors.lastname: Woolard
authors.forename: Wees
authors.initials: W
authors.lastname: Love
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Simecka
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002417:Cattle; D003612:Dairying; D004432:Ear, Middle / Q000382:microbiology / Q000473:pathology; D005064:Eustachian Tube / Q000382:microbiology / Q000473:pathology; D018928:Immunity, Mucosal; D045682:Mycoplasma bovis / Q000254:growth & development*; D010033:Otitis Media / Q000276:immunology / Q000382:microbiology*; D014066:Palatine Tonsil / Q000276:immunology / Q000382:microbiology*