GENE ‘SWITCH’: Could Offer New Arsenal Against Superbugs
A "master switch" that turns off virulent genes in disease-causing bacteria offers a promising new approach to vaccine and antibiotic development, according to a study published in today's issue of Science. Lead author Michael Mahan of the University of California-Santa Barbara discovered the switch, which is being hailed as a significant development in the race to find new antibiotics to outpace antibiotic-resistent bacteria. The California team found that an enzyme, called dam, serves as an on/off switch for an arsenal of weapons that bacteria employ to infect humans. Bacteria that lack the gene for the damaging enzymes are disarmed, but nonetheless trigger an immune response in the host. "The bacteria are completely disabled in their ability to cause disease, and these crippled bacteria work as a vaccine since they stimulate immune defenses against subsequent infections," Mahan said (BBC News, 5/7). The researcher injected 25 mice with a Salmonella bacteria lacking the dam gene, and then challenged the mice with a "massive dose" of a pathogenic form of the Salmonella. None was harmed by the injection, Mahan said. Dam exists in other infectious bacteria, including those that cause cholera, plague, typhoid, dysentery, meningitis and E. coli poisoning, and Mahan said he will conduct experiments to determine if the enzyme has the same disarming role (Maugh II, Los Angeles Times, 5/7).
John La Montagne, deputy director of the National Institute of Allergy and Infectious Diseases, called the findings "significant," noting that the discovery will likely "trigger a lot of additional work in this area." Thomas Cebula, director of the FDA's Division of Molecular Biological Research and Evaluation unit agreed, saying, "We're fast returning to the pre-antibiotic era of medicine. I'm not saying this is a panacea, but we certainly need more fresh thinking to solve this problem" (Hall, San Francisco Chronicle, 5/7). Mahan said that human trials "could conceivably begin in only a couple of years" (Los Angeles Times, 5/7).