Innate Immune Response to Intramammary Mycoplasma bovis Infection

Abstract

The objective of the current study was to characterize the systemic and local innate immune response of dairy cows to IMI with Mycoplasma bovis, a pathogen of growing concern to the dairy industry. Ten Holstein cows were each infused in 1 quarter with M. bovis and studied for a 10-d period. Acute phase protein synthesis, which reflects 1 parameter of the systemic response to infection, was induced within 108 h of infection, as evidenced by increased circulating concentrations of lipopolysaccharide binding protein and serum amyloid A. Transient neutropenia was observed from 84 to 168 h postinfection, whereas a constant state of lymphopenia and thrombocytopenia was observed from 84 h until the end of the study. Milk somatic cell counts initially increased within 66 h of M. bovis infusion and remained elevated, relative to control (time 0) concentrations, for the remainder of study. Increased milk concentrations of BSA, which reflect increased permeability of the mammary epithelial-endothelial barrier, were evident within 78 h of infection and were sustained from 90 h until the end of the study. Milk concentrations of several cytokines, including IFN-gamma, IL-1beta, IL-10, IL-12, tumor growth factor-alpha, and tumor necrosis factor-alpha, were elevated in response to infection over a period of several days, whereas increases in milk IL-8 were of a more limited duration. Complement activation, reflected by increased milk concentrations of complement factor 5a, was also observed over several days. Despite the indication by these observed changes that the cows mounted a prolonged inflammatory response to M. bovis intramammary infection, all quarters remained infected throughout the study with persistently high concentrations of this bacterium. Thus, a sustained inflammatory response is not sufficient to eradicate M. bovis from the mammary gland and may reflect the ongoing struggle of the host to clear this persistent pathogen.

Effects of hydrolyzed yeast supplementation in calf starter on immune responses to vaccine challenge in neonatal calves

“…To obtain more insight into the effects of yeast products on blood cell composition in an experimental infection model using neonatal calves, we conducted blood cell composition analysis. A previous study reported that cattle infected with Mycoplasma bovis showed systemic responses, including leukopenia, lymphopenia, neutropenia and thrombocytopenia, during the first few days of the infection, and it has also been reported that leukopenia occurs early in bacterial infections in ruminants (Kahn and Line, 2005;Kauf et al, 2007). In this study, different tendencies for changes in blood cell composition were observed between groups after vaccine challenge.…”

Mycoplasma Mastitis

“…54 Given their simple nature and fastidious growth requirements, they find ecological niches within their host. In cases of intramammary infections, Mycoplasma sp do not appear to often cause a significant, if any, febrile response, 48,55,56 which may be consistent with their nature to colonize cows asymptomatically.…”

Acute phase proteins in ruminants

“…These increases were related to increased levels in milk of a range bovine cytokines including IL-1β, IFN-γ and TNF-α. Monitoring the changes in serum LBP and SAA concentrations has also been used to characterize the innate immune response to experimental induction of mastitis with Mycoplasma bovis infection [180]. The increases in serum LBP and SAA were compared along with other markers of the innate immune response, such as cytokines, between Holstein and Jersey breeds of dairy cows.…”