Innate Immune Response to Intramammary Mycoplasma bovis Infection

• Published in: Journal of dairy science 2007-07, Vol.90 (7), p.3336-3348
• Main Authors: Kauf, A.C.W., Rosenbusch, R.F., Paape, M.J., Bannerman, D.D.
• Format: Article
• Language: English
• Subjects: Aflatoxin B1 - analysis; Animal productions; Animals; Biological and medical sciences; bovine mastitis; Cattle - immunology; Colony Count, Microbial - veterinary; Complement Activation - immunology; Complement C5a - analysis; Cytokines - analysis; dairy cow; dairy cows; Dairying; disease resistance; Female; Food industries; Fundamental and applied biological sciences. Psychology; Holstein; immune response; Immunity, Innate - immunology; innate immunity; Lymphopenia; mastitis; Mastitis, Bovine - immunology; Mastitis, Bovine - microbiology; Milk - chemistry; Milk - cytology; Milk and cheese industries. Ice creams; Mycoplasma bovis; Mycoplasma bovis - immunology; Mycoplasma Infections - immunology; Mycoplasma Infections - microbiology; Mycoplasma Infections - veterinary; mycoplasmosis; Neutropenia; Serum Albumin - analysis; Terrestrial animal productions; Thrombocytopenia; Time Factors; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2007-0058

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 108h of infection, as evidenced by increased circulating concentrations of lipopolysaccharide binding protein and serum amyloid A. Transient neutropenia was observed from 84 to 168h postinfection, whereas a constant state of lymphopenia and thrombocytopenia was observed from 84h until the end of the study. Milk somatic cell counts initially increased within 66h 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 78h of infection and were sustained from 90h until the end of the study. Milk concentrations of several cytokines, including IFN-γ, IL-1β, IL-10, IL-12, tumor growth factor-α, and tumor necrosis factor-α, 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.