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Title: RECOMBINANT BOVINE SOLUBLE CD14-REDUCES SEVERITY OF EXPERIMENTAL ESCHERICHIA COLI MASTITIS IN MICE

Author
item LEE, JAI-WEI - MCGILL UNIV, CANADA
item Paape, Max
item ZHAI, XIN - MCGILL UNIV, CANADA

Submitted to: Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2003
Publication Date: 6/1/2003
Citation: LEE, J., PAAPE, M.J., ZHAI, X. RECOMBINANT BOVINE SOLUBLE CD14-REDUCES SEVERITY OF EXPERIMENTAL ESCHERICHIA COLI MASTITIS IN MICE. VETERINARY RESEARCH. vol. 34, pp. 307-16, 2003.

Interpretive Summary: When coliform bacteria invade the mammary gland of dairy cows, their numbers rapidly multiply. Within hours, millions of slender, rod-shaped microorganisms fill the lumen of the mammary gland. They settle against the velvety convolutions of the milk secretory cells, absorbing the abundant nutrients and expelling their own poisonous secretions called endotoxins. These secretions burn like acid resulting in instant destruction of the mammary cells. As these toxins escape the gland and spread throughout the body the animal becomes feverish, acutely sick, goes into shock and dies. Scientists at the USDA-ARS research facility in Beltsville, Maryland have produced a protein called CD14. CD14 quickly binds and neutralizes endotoxin. Then, the CD14-endotoxin complex attracts spcialized, first-line-of-defense cells called neutrophils to infection sites, where they quickly destroy the coliform organisms. The scientists conducted studies in mice and were able to show that CD14 protected mice from endotoxin shock and reduces clinical symptoms associated with coliform mastitis. The USDA scientists plan on using CD14 in dairy cows to prevent intramammary infection or mastitis by coliform bacteria, a billion dollar a year loss to the dairy industry.

Technical Abstract: Recombinant bovine sCD14 (rbosCD14) was produced by transfected insect sf/9 cells and its biological function was evaluated in mice. Eighty-one 8-wk old BALB/cj female mice were randomly assigned to two groups, and injected intraperitoneally with either LPS (8 ug/gbw, n = 41) or LPS plus rbosCD14 (6.8 ug/gbw, n = 40). Survival rate at 24 hours after injection for mice injected with either LPS or LPS plus rbosCD14 was 30 and 72 % (P < 0.01). At 48 hours survival rate was 7 and 37 % (P < 0.01). To investigate the protective effect of rbosCD14 on experimentally induced mastitis in mice, two abdominal mammary glands of 7 lactating BALB/cj mice were injected through the teat canal with 10-20 colony-forming units (CFU) of Escherichia coli. One gland simultaneously received rbosCD14 (6 ug) and the other saline. At 24 hours after challenge, glands that received rbosCD14 had less swelling and hemorrhaging, significantly lower bacterial counts (P < 0.05) and lower concentrations of TNF-a (P < 0.05). Results indicate that rbosCD14 is biologically functional and reduces mortality in mice from endotoxin shock and severity of intramammary infection by E. coli.