Bacterial DNA may bolster vaccine power

Saskatoon, Sask., January 16, 2002

Conventional protein vaccines are being given a boost with bacterial DNA to improve their infection-fighting power, report researchers at the Veterinary Infectious Disease Organization (VIDO) in Saskatoon.

Normal protein vaccines work by introducing a protein that stimulates an immune response to a single disease-causing organism. “By mixing synthetic bits of bacterial DNA (CpG) into conventional protein vaccines, we can make them more potent and more able to help the immune system recognize and respond to a disease threat,” says Dr. George Mutwiri, VIDO CpG Program Coordinator.

Benefits are twofold: These high-powered vaccines will strengthen the animal’s response, and will potentially save producers time as well as money by avoiding re-vaccination, he says. While bacterial DNA enhances animal immune responses, no tissue reactions occur, discovered Dr. Sylvia van den Hurk, a VIDO Senior Scientist, Virology, and a project collaborator. Tissue reactions from vaccines can damage meat quality.

Cattle are the prime focus of the project, but swine and poultry are also included. Mutwiri and his team are working to optimize formulation and dosage.

Underlying this new vaccine development is an understanding of the two recognition systems of the immune system: the innate and the adaptive.

The innate system recognizes certain features that are characteristic of a family of micro-organisms. When this “microbial pattern” is identified, an immune response is triggered, Mutwiri says. “Now, scientists have learned bacterial DNA or certain sequences of bacterial DNA are recognized by the immune system, activating an immune response,” he adds.

While the innate system only recognizes microbial patterns, the adaptive system has evolved to recognize specific micro-organisms. When the adaptive system recognizes a dangerous micro-organism, it activates specific immune cells and produces a specific antibody to fight it. “An antibody that works against Campylobacter, for example, won’t work for E. coli. Vaccines work because we’re teaching the immune system to identify a specific organism,” says Mutwiri.

The new DNA-enhanced vaccines are designed to fine-tune the process by which the innate system and the adaptive system work together. “If the innate system is boosted, stronger signals are sent to the adaptive system. The adaptive system then improves its ability to produce antibodies for fighting an infection. It also becomes quicker at identifying that infection in the future,” he says.

Coupled with the vaccine research, is an effort to use bacterial DNA to develop an immunostimulant product that will enhance animal resistance to a variety of diseases.

“Bacterial DNA-enhanced vaccines are still a number of years a way, but we expect they will give producers a powerful, cost-effective tool in controlling diseases.”

VIDO, a non-profit research institute wholly owned by the University of Saskatchewan, is a global leader in food animal and poultry vaccine research for infectious diseases. It operates with substantial support from the Province of Alberta and the Province of Saskatchewan. This project is funded by a Cooperative Research and Development Grant from Natural Sciences and Engineering Research Council of Canada, Qiagen, the Canadian Adaptation and Rural Development Program, Saskatchewan Horned Cattle Trust Fund, Saskatchewan Cattle Marketing Deductions Fund, Manitoba Cattle Producers, Kamloops Stockmen’s Association, Alberta Pork, Sask Pork and Manitoba Pork.

For more information, contact:

Stuart Bond
Associate Director, Marketing and Business Development
Veterinary Infectious Disease Organization
Phone: (306) 966-7474
Fax: (306) 966-7478