Reproduction of respiratory mycoplasmosis in calves by exposure to an aerosolised culture of Mycoplasma bovis

Abstract

Mycoplasma bovis is an important pathogen of cattle, causing pneumonia, arthritis and otitis media in young calves, and mastitis in lactating cows, resulting in increased morbidity and, in some instances, mortality. The objective of this study was to evaluate the survival of a M. bovis isolate following nebulisation and to establish whether respiratory disease similar to that seen in the field could be induced in calves by exposing them to an aerosolised culture of M. bovis. A group of eight M. bovis-free calves 14-28days old were exposed to an aerosolised culture of a field isolate of M. bovis that had originally been recovered from a joint lesion in a calf. Three weeks after aerosol exposure necropsies were conducted on all calves. Lung lesions were seen in 7 of 8 calves exposed to the aerosol of M. bovis, whilst calves exposed to the culture medium alone did not develop lesions. Two calves in the infected group had detectable concentrations of serum antibody against M. bovis on day 7 post infection and 4 calves had detectable concentrations of serum antibody against M. bovis on day 21 post infection when tested by MilA IgG ELISA. M. bovis was reisolated from the upper trachea of 6 of the 8 infected calves. The infection method described here appeared to induce lung lesions typical of naturally occurring disease associated with infection with M. bovis and should be applicable to testing the safety and efficacy of attenuated vaccine candidates to control disease caused by this pathogen.

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

“…To be able to test candidate vaccines (whether subunit‐based, bacterin or an attenuated live vaccine), reproducible animal challenge models are required for both respiratory disease and mastitis. In this regard, it will be of interest to further validate the recently reported aerosol challenge model for M. bovis in calves (Kanci et al., ). Concerns needing resolution include the variability of the surface proteins expressed by M. bovis and the possible requirement to use multiple strains in a vaccine.…”

Mycoplasma bovis Infections—Occurrence, Diagnosis and Control

“…The role of airborne transmission of M. bovis is unclear with little experimental evidence supporting this route of infection [ 37 , 38 ]. In response to exposure of calves to aerosolized M. bovis , respiratory disease was induced.…”

Increased incidence rate of undesired early heifer departure in Mycoplasma bovis-antibody positive Danish dairy cattle herds

“…This variable reflects the M. bovis status among calves aged 3-12 months in the herd. Despite antibodies against M. bovis are not recommended for individual diagnosis (Maunsell and Donovan, 2009), an increase in antibody titre occur after exposure to M. bovis (Kanci et al, 2017) and the seroprevalence in a group of calves is assumed to be a useful measure of exposure to M. bovis. When using antibody measurements the ELISA test used can influence the results.…”