Studies by veterinary researchers at Kansas State University, with collaboration from Epitopix LLC, have resulted in the United States' first vaccine against E. coli O157 in beef cattle.
"Researchers have done so much to focus on the post-harvest food safety aspect, whether it's E. coli or salmonella," said Dan Thomson of K-State's College of Veterinary Medicine. Thomson is the Jones Professor of Production Medicine and Epidemiology in the department of clinical sciences.
"Controlling foodborne pathogen outbreaks, and specifically E. coli O157, has been a major research initiative of many government and private agencies for the last two decades," he said. "We're really excited about the potential of this vaccine to aid pre-harvest food safety in beef cattle."
Thomson led both challenge studies and field studies to help the vaccine garner approval from the U.S. Department of Agriculture. It was developed by researchers Daryll Emery, Darren Straub and Doug Burkhardt of Epitopix LLC in Willmar, Minn. Thomson collaborated with T.G. Nagaraja, university distinguished professor of diagnostic medicine and pathobiology at K-State, and Guy Loneragan of West Texas A&M University.
"We're excited that this vaccine has been granted a conditional approval by the U.S. Department of Agriculture," Thomson said. "We have been a research collaborator for Epitopix to conduct the work that lead to this conditional approval. Epitopix will now be able to offer this pre-harvest food safety tool to beef producers."
The researchers conducted a challenge study at K-State and studies of commercial feed yards in Nebraska and Great Bend in 2007 and 2008.
"With this vaccine, we observed decreases in cattle shedding E. coli O157," Thomson said. "In our last field study we observed an 86 percent reduction in the number of animals shedding E. coli. Of the vaccinated cattle that were still shedding, we observed nearly a 98 percent reduction of E. coli O157 fecal concentration.
"Epitopix LLC has had many successes with this technology in other industries including poultry and dairy," Thomson said. "They have a product currently on the market for control of Salmonella in dairy cows."
E. coli, like other foodborne pathogens, is a bacteria that is present in the gastrointestinal tract of healthy cattle. Foodborne pathogens can contaminate meat or vegetable products. If food isn't properly cooked, the bacteria can harm the people who eat it. More information on proper ways to cook meat is available at: http://www.oznet.ksu.edu/news/sty/2001/2meat1a.htm
Thomson said the vaccine works by not allowing the E. coli bacteria to acquire iron. Instead of targeting the whole bacterium, this vaccine targets certain proteins and protein receptors on the surface on the bacteria. When antibodies block these proteins and protein receptors, the bacteria can't absorb iron and are not able to grow or reproduce.
"Iron is to bacteria what oxygen is to humans," he said.
Thomson said K-State appreciates the research partnership with Epitopix on this important pre-harvest food safety tool and that the partnership allowed several K-State graduate students to participate in the study. They included Trent Fox, a December 2007 doctoral graduate in pathobiology and now a third-year veterinary medicine student, St. John; Ashley Thornton, a December 2007 master's degree graduate in biomedical science, St. Joseph, Mo.; and Ben Wileman, a doctoral student in pathobiology, Belle Fourche, S.D.
Thomson said the next step for the K-State researchers is to conduct post-approval studies on the vaccine by looking at its effects on cow herds at the ranch before the calves arrive at the feed yards. This includes studying whether cows can pass the resistance on to their calves.