Judy Jamison 

Mastitis, a kind of infection of mammary tissue, costs the US dairy industry billions annually, and extracts an uncalculable cost in animal suffering. On page 66, Kerr et al. demonstrate a possible biotechnology solution: transgenic mice that secrete in their own milk a potent antibacterial protein, lysostaphin, that targets one of the main culprits, Staphylococcus sp. They introduced a pair of mutations in the bacterial lysostaphin gene that conferred staphylolytic activity, and fused it to part of the ovine -lactoglobulin gene to mediate secretion into milk. Transgenic mice expressing the construct proved highly resistant to S. aureus infection, and were apparently otherwise unaffected.