A biologist at Washington University in St. Louis has developed a live vaccine that should greatly decrease the incidences of food poisoning and deaths in humans infected by salmonella bacteria.
Roy Curtiss III, Ph.D., George William and Irene Koechig Freiberg Professor of Biology in Arts and Sciences, has genetically engineered the most common strain of salmonella infecting chickens and developed it as an oral vaccine to be given to poultry. Curtiss deleted two key genes in the strain Salmonella typhimurium UK-1; the deletion weakens the bacteria, allowing it in vaccine form to induce an immune response in a chicken without making the bird sick.
When given a dose of the vaccine, newborn chicks, breeders and laying hens develop a lifelong immunity to salmonella. The immunity is transferred to offspring and eggs that people consume.
The vaccine is in its final stage of testing by scientists at Megan Health Inc. in St. Louis, a company licensed by Washington University to develop and market vaccines based on technology developed by Curtiss.
The U.S. Department of Agriculture (USDA) is expected to license the vaccine by the end of 1997. Megan's vaccine will be the first salmonella vaccine for poultry marketed in the United States.
Curtiss reported the vaccine test results July 29, 1997, at the International Veterinary Vaccines and Diagnostics Conference, held in Madison, Wis.
"Based on years of research and testing, we are confident that our vaccine works very well," says Curtiss, who first developed the strain for his vaccine in 1990, and has spent 17 years researching salmonella bacteria.
When virulent bacteria are introduced into an organism, a fight ensues between the bacteria and the host's immune system.
"By deleting the genes, we make sure that the salmonella has its hands tied behind its back," Curtiss explains. "With those two genes, the salmonella could defend itself against the chicken's na
Contact: Tony Fitzpatrick
Washington University in St. Louis