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.

Gap analysis ofMycoplasma bovisdisease, diagnosis and control: An aid to identify future development requirements

“…M. bovis was first detected as a cause of bovine mastitis in the United States in the 1960s (Hale, Helmboldt, Plastridge, & Stula, ) and has since been detected in most countries worldwide with only a few exceptions (Nicholas, ). The clinical disease caused by M. bovis can be very variable and includes mastitis, pneumonia, arthritis, genital disorders and keratoconjunctivitis which can occur in cattle of all ages (Nicholas & Ayling, ), as well as otitis media in younger animals (Maunsell et al., ; Walz et al., ). Infected cattle can become asymptomatic carriers and may shed the organism through nasal discharges or in milk for months to years without showing clinical signs (Nicholas, Ayling, & McAuliffe, ; Wilson et al., ).…”

BIGHORN SHEEP (OVIS CANADENSIS) SINUS TUMORS ARE ASSOCIATED WITH COINFECTIONS BY POTENTIALLY PATHOGENIC BACTERIA IN THE UPPER RESPIRATORY TRACT

“…Splenic and thymic lymphoid depletion were present in most cases and suggested chronic stress or disease. Lambs with pneumonia also consistently had suppurative otitis media, a condition associated with Mycoplasma bovis in dairy calves (Maunsell et al 2012) and Pasteurellaceae in domestic lambs (Macleod et al 1972;Jensen et al 1982).…”

The presence of Mycoplasma bovis in colostrum

“…Colostrum was mentioned as a possible source of M. bovis in the past [9,10], but to the author's knowledge, no studies on the prevalence of M. bovis in colostrum are currently available. Despite this lack of information, empirically designed M. bovis herd control programs often advocate the removal or (heat-) treatment of the herd's own colostrum as a precaution measure [4].…”