DNA vaccines offer potentially cheaper alternative for disease control

DNA vaccines are still in the experimental stage of development, but they could provide livestock producers with a cost-effective alternative to other types of vaccines, says a research scientist at the University of Saskatchewan’s Veterinary Infectious Disease Organization (VIDO).

DNA (deoxyribonucleic acid) vaccines consist of a circular piece of DNA containing the gene needed to produce a protective protein in the cells of an animal, says Virologist Dr. Sylvia van den Hurk, a VIDO Senior Scientist investigating DNA vaccines. The protective protein generates the immune response against a particular disease-causing organism.

“In comparison to protein vaccines, DNA vaccines could become easier to administer, depending on the cost-effective commercialization of delivery technology that injects the DNA vaccine into the skin. DNA vaccines will also be easier and cheaper to produce,” she says. “As well, DNA vaccines are highly effective when delivered in the skin with needle-free devices, meaning no meat loss because of tissue damage.”

DNA vaccines are also advantageous from a safety perspective because they exist in the cells independently and do not enter the genetic material of the animals, says van den Hurk. “The DNA does not duplicate itself.”

To learn more about DNA vaccines, van den Hurk and her team first used infectious bovine rhinotracheitis virus (IBRV) as a model virus to work with. “IBRV is a good challenge model because we have the genes and agents to work with,” she says.

From that work with IBRV, van den Hurk has demonstrated that a DNA vaccine produces the same level of protection as other vaccines. Other viruses such as bovine viral diarrhea virus (BVDV) are next in VIDO’s research sights. “We have the genes and the protective proteins for the other viruses and have put the genes in the circular DNA. In mouse models, the vaccines have worked successfully for a number of the viruses.”

However, it’s more difficult to perform the experiments with cattle and that will take an additional two years to complete, she says.

While the research continues on the ability of DNA vaccines to become viable alternatives for livestock producers, safety data must also be collected. “Basically, the DNA is administered into the skin so that it can get into the cells. The DNA exists in the skin cells for a period of time and then it comes to the skin surface and slides off. The vaccine takes around two months to leave the system and after that we find no traces of the vaccine in the animal,” says van den Hurk.

Experimental DNA vaccines for human viruses such as HIV, AIDS, Hepatitis B and Influenza are currently being conducted in human clinical trials at human research institutions, she points out. “So they are considered safe.”

On the human health side, van den Hurk has no concern about whether people should consume meat from animals that have been administered a DNA vaccine. “In my opinion, we shouldn’t worry because we eat DNA everyday in large amounts. Everything from vegetables to meat contains DNA.”

Van den Hurk cautions that although DNA vaccines show promise for the cost-effective control of livestock diseases, research needs to continue to ensure their efficacy and safety. This is the case with all vaccines. “We need to do more work on these vaccines before we know if they can be a viable product for researchers to develop and bio-pharmaceutical companies to produce. But so far, the principles are sound,” she says.

Funding sources for the DNA immunization project are: National Science and Engineering Research Council of Canada, Canadian Institutes of Health Research, Alberta Beef Industry Development Fund, Alberta Agriculture Research Institute, Beef Cattle Industry Development Fund, Ontario Cattleman’s Association, Manitoba Cattle Producers Association, Kamloops Stockmen’s Association, Saskatchewan Horned Cattle Trust Fund, Saskatchewan Cattle Marketing Deductions Fund, the Governments of Manitoba and British Columbia and Agricultural Development Fund of Saskatchewan.

VIDO, located in Saskatoon, is a global leader in food animal and poultry vaccine research for the control of infectious diseases. It operates with significant support from the Province of Alberta and Province of Saskatchewan.

For more information, contact:

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