A new way to guard against Lyme disease.

HEALTH LYME PROTECTION Outdoor lovers now have a new defense against Lyme disease, a bacterial infection transmitted by ticks. A vaccine, invented by Stephen Barthold, director of the UC Davis Center for Comparative Medicine, and colleagues, was approved by the Food and Drug Administration in December and now sells under the brand name Lymerix. A comparative veterinary pathologist, Barthold directed a National Institutes of Health program at Yale University School of Medicine and contributed to the development of the genetically engineered vaccine, which uses recombinant outer surface protein A (OspA). In collaboration with colleagues at Yale (where co-inventors Richard Flavell, Fred Kantor and Erol Fikrig still work), UC Davis and other institutions, Barthold has since evaluated many additional proteins as potential second-generation vaccines for prevention of Lyme disease, as well as for treatment of existing infection. This work has been facilitated by Barthold's efforts at Yale to develop a widely utilized mouse model for Lyme disease. In 1997, Barthold--a UC Davis alumnus who received a B.S. in 1967 and a D.V.M. in 1969--returned to campus as director of the new Center for Comparative Medicine, where he continues his investigations. The center brings scientists from human and veterinary medical disciplines together to investigate Lyme disease, AIDS and other persistent infectious diseases common to humans and animals. Barthold also serves as a national scientific adviser to the American Lyme Disease Foundation. The OspA vaccine is effective at preventing infection, but the most difficult issues in Lyme disease are those related to how to eliminate ongoing infection or ameliorate the disease. His current research aims to identify the Lyme disease bacterial gene products that stimulate effective host immunity in the hope of developing a therapeutic vaccine. Lyme disease affects both humans and animals. Doctors can use antibiotics to treat early Lyme disease in most cases, but in a small number of individuals, particularly those that go undiagnosed for long periods, the illness can be difficult to treat and may lead to serious complications. "These patients have a serious, debilitating disease that warrants continued research effort in understanding how this agent persists and causes disease and how to manipulate the host-agent relationship to favor the patient," said Barthold. Certain areas of California are well-known habitats for the Western black-legged tick, which transmits the disease by attaching itself to hikers, campers and pets in grassy or wooded areas. Three doses of Lymerix, manufactured and marketed by SmithKline Beecham Biologicals, have been shown in tests to prevent infection in up to 78 percent of recipients between 15 and 70 years old. The FDA has not approved the vaccine for children under 15 years of age, pregnant women or individuals with a previous history of arthritis or Lyme disease. It is not yet clear how long the vaccine remains effective. Barthold cautions that prevention of Lyme disease should never depend entirely on a vaccine. Important ways to prevent Lyme disease include tick eradication, use of insect repellent, wearing of protective, light-colored clothing (so the dark ticks are visible), remaining on well-cleared trails and checking for hitchhiking ticks on all hikers and pets after outdoor excursions.