Nature Biotechnology
19, 66 - 70 (2001)
doi:10.1038/83540
Lysostaphin expression in mammary glands confers protection against staphylococcal infection in transgenic miceDavid E. Kerr1, Karen Plaut1, A. John Bramley1, 2, Christine M. Williamson2, 3, Alistair J. Lax2, 4, Karen Moore5, 6, Kevin D. Wells5
& Robert J. Wall51
Department of Animal Sciences, University of Vermont, Burlington, VT 05405. 2
Institute for Animal Health, Compton Laboratory, Berks RG20 7NN, UK. 3
Current address: MRC Mammalian Genetics Unit, Harwell, Didcot, Oxfordshire, OX11 0RD, UK. 4
Current address: Oral Microbiology, King's College London, London SE1 9RT UK. 5
Gene Evaluation and Mapping Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705. 6
Current address: Department of Animal Sciences, University of Florida, Gainesville, FL 32611.
Correspondence should be addressed to David E. Kerr dkerr@zoo.uvm.edu
mastitisanimal biotechnologyantibacterial proteinStaphylococcus aureusInfection of the mammary gland, in addition to causing animal distress, is a major economic burden of the dairy industry. Staphylococcus aureus is the major contagious mastitis pathogen, accounting for approximately 15−30% of infections, and has proved difficult to control using standard management practices. As a first step toward enhancing mastitis resistance of dairy animals, we report the generation of transgenic mice that secrete a potent anti-staphylococcal protein into milk. The protein, lysostaphin, is a peptidoglycan hydrolase normally produced by Staphylococcus simulans. When the native form is secreted by transfected eukaryotic cells it becomes glycosylated and inactive. However, removal of two glycosylation motifs through engineering asparagine to glutamine codon substitutions enables secretion of Gln125,232-lysostaphin, a bioactive variant. Three lines of transgenic mice, in which the 5'-flanking region of the ovine  -lactoglobulin gene directed the secretion of Gln125,232-lysostaphin into milk, exhibit substantial resistance to an intramammary challenge of 104 colony-forming units (c.f.u.) of S. aureus, with the highest expressing line being completely resistant. Milk protein content and profiles of transgenic and nontransgenic mice are similar. These results clearly demonstrate the potential of genetic engineering to combat the most prevalent disease of dairy cattle.
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