Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2000
Publication Date: 10/1/2000
Citation: Tomita, G., Wang, Y., Paape, M.J., Poutrel, B., Rainard, P. 2000. Influence of Bispecific Antibodies on the In Vitro Bactericidal Activity of Bovine Neutrophils Against Staphylococus Aureus. Journal of Dairy Science. 83(10):2269-2275. Interpretive Summary: Mastitis cost the U.S. dairy industry over 2 billion dollars annually. This year 6 million clinical cases of mastitis will occur in the 9 million dairy cows in the U.S. Antibiotics will be administered to most of these cows resulting in potential contamination of the human food supply. In looking for a nonantibiotic approach for the treatment of this disease, scientists at the Immunology and Disease Resistance Laboratory, USDA, ARS, Beltsville, developed the worlds first bispecific antibodies for the treatment and prevention of clinical mastitis. The antibodies were produced by linking antibodies to neutrophils, a type of white blood cells that kill bacteria, to monoclonal antibodies to Staphylococcus aureus. When this coupled antibody is injected into the mammary gland one end hooks up to the pathogen and the other end snags its terminator the neutrophil. This contact triggers the neutrophil to release a lethal spray of hydrogen peroxide that kills the pathogen. In laboratory tests, the bispecific antibodies enhanced the killing of Staphylococcus aureus by neutrophils.
Technical Abstract: Bispecific antibodies were synthesized by chemically crosslinking bovine polymorphonuclear neutrophil leukocyte (PMN) monoclonal antibodies to Staphylococcus aureus 305 capsule polysaccharide monoclonal antibodies. Staphylococcus aureus 305 was preincubated with various concentrations of bispecific antibodies. Bovine PMN were then added to the opsonized bacteria at different bacteria to PMN ratios and briefly incubated. Aliquots were then plated on trypticase-soy blood agar and colony forming units (CFU) were enumerated following an overnight incubation. The bactericidal activity of PMN was expressed as a percent reduction in CFU in test cultures compared to the number of CFU in control test cultures that did not contain bispecific antibodies. Addition of bispecific antibodies to test cultures increased the bactericidal activity of PMN. Increasing concentrations of bispecific antibodies enhanced the bactericidal activity of PMN. Results indicate that bispecific antibodies that recognize both S. aureus and PMN potentiates the bactericidal activity of PMN.