Promising cattle vaccine could reduce E. coli O157:H7 threat

Saskatoon, Sask., April 3, 2001

A new vaccine for controlling E. coli O157:H7 in cattle could become an important management tool in the cattle industry’s crusade against the hazardous bacteria as well as in society’s efforts to deal with the food safety concerns and control the disease at the human level. The vaccine was developed through a collaboration between the Veterinary Infectious Disease Organization (VIDO) at the University of Saskatchewan in Saskatoon, the University of British Columbia (UBC) in Vancouver, and the Alberta Research Council in Edmonton.

E. coli O157:H7 infection in humans, coined as the “hamburger disease” by the media, garnered immense public attention last year because of its threat to human health, especially to children and the elderly.

Dr. Andy Potter, VIDO Associate Director (Research), and Dr. Brett Finlay, UBC, became interested in developing a vaccine for controlling the bacteria after Finlay identified several novel bacterial components required for the E. coli O157:H7 bacteria and related organisms to infect the intestine. Knowing that as many as 50 percent or greater, of all cattle shed the bacteria at some point during their lives, Potter and Finlay believed a vaccine to control the bacteria in cattle could help control its spread to humans.

The project to develop an E. coli O157:H7 vaccine for cattle began three years ago before the bacteria and its potential human health effects moved to the forefront of public attention. Potter and Finlay, whose work was primarily in human health at that point, applied for and received a grant from the Canada Beef Industry Development Fund to conduct the research. The research was also supported by the Canadian Bacterial Disease Network in Calgary, Alberta, which has remained a partner in the further development of this technology.

By vaccinating cattle with those specific proteins, Potter and Finlay have been able to significantly reduce the colonization of the bacteria in the gut of cattle.

“We’ve been able to demonstrate that by using technology developed by Finlay, it’s possible to substantially reduce the levels of E. coli O157:H7 in vaccinated cattle,” says Potter. He emphasizes that the vaccine is specific to the deadly strain and its close relatives. Currently, no vaccine or other methods exist for effectively controlling E. coli O157:H7, but vaccines that control other types of disease caused by the E. coli bacteria in cattle are commercially available.

“Immunized animals should harbour fewer E. coli O157:H7 bacteria and therefore present a reduced risk of contamination at the slaughter level,” he says. With lower levels of bacteria shed by vaccinated cattle, the risk of E. coli O157:H7 infecting humans through environmental sources, should also be reduced.

The commercial partners of UBC and VIDO, Alberta Research Council and Bioniche Life Sciences Inc., are currently producing large quantities of the vaccine for the safety and efficacy trials needed for licensing. In September 2001, large-scale field trials will begin on 30,000 to 70,000 cattle. This work is being funded in part by the Alberta Agricultural Research Institute.

Field trials for the vaccine are expected to last eight to 12 months, but Potter expects the required data for licensing the vaccine will be available within the first two months of the field study. Once the vaccine has received approval, Potter hopes it will be marketed as quickly as possible. The field trials will examine other factors that can affect vaccination efficacy, such as the use of different management practices and immunization schedules.

“If this vaccine holds up in the field trials, it could become an important tool for controlling this bacteria and a boon for the industry, which is working hard to find solutions to this food safety issue.”

Both Potter and Finlay know the vaccine reduces the output of E. coli O157:H7 in manure, but they need to learn more about how the bacteria works inside the cattle gut.

The proteins used in the vaccine are involved in attachments in the gut, so in theory, they should be great vaccine components, says Potter. “They are rather unique, in that the bacteria actually injects at least one of these proteins into the host cell and then attaches to it, so it carries its own receptor around and injects it whenever it has to. This has been demonstrated in mice and humans, but we don’t have direct evidence of this occurring in cattle.”

Further research is currently underway to demonstrate that this process is involved in the colonization of cattle by E. coli O157:H7. Initial results are validating the vaccine results, says Potter. In the long term, VIDO will conduct further research into food safety issues such as E. coli O157:H7. “Food safety is a big issue and we see significant expansion in that area in the coming years,” says Potter. “It also fits with VIDO’s vision of capitalizing on human health research and transferring applicable knowledge into veterinary medicine and vice versa.”

VIDO is a not-for-profit organization with significant support from the Government of Alberta and Government of Saskatchewan. It is a global leader in food animal and poultry vaccine research for the control of infectious diseases and is wholly owned by the University of Saskatchewan. The E. coli O157:H7 project received core funding from: Saskatchewan Horned Cattle Trust Fund, Saskatchewan Cattle Marketing Deductions Fund, Kamloops Stockmen’s Association and Manitoba Cattle Producers.

For more information, contact:

Dr. Andrew Potter
Associate Director (Research)
Veterinary Infectious Disease Organization
Phone: (306) 966-7484
Fax: (306) 966-7478
E-mail: potter@sask.usask.ca

Stuart Bond
Associate Director, Producer Relations
Veterinary Infectious Disease Organization
Phone: (306) 966-7474
Fax: (306) 966-7478