“Double-barreled” live viral vectored vaccines target beef diseases

Saskatoon, Sask., June 14, 2001

Costly beef respiratory and intestinal diseases may have a potent new enemy in the form of new live viral vectored vaccines under development at the Veterinary Infectious Disease Organization (VIDO) in Saskatoon, Sask.

Bovine respiratory and intestinal diseases cost North American cattle producers approximately $1 billion and $300 million respectively each year.

“One of the most effective ways to fight these disease-causing viruses is to use vaccines that directly target the appropriate site in the body and induce an immune response,” says Dr. Suresh Tikoo, VIDO Virology Program Manager. “Live viral vectored vaccines are an excellent way to deliver the antigens to the right area of the body for the most effective defensive response to a particular disease.”

Tikoo and his team are using the Bovine adenovirus-3 (BAV-3) as the delivery vehicle for the antigens of diseases such as bovine viral diarrhea (BVD). “BAV-3 is ideal because it infects the bovine respiratory tract. Also, we have identified a number of regions within the virus that can be deleted to cripple the virus so it will not cause disease.” By replacing the deleted genes with the protective antigens of respiratory disease-causing organisms, we can produce a single-shot multivalent vaccine that induces immunity to a variety of diseases in cattle - in other words “a double-barreled approach,” says Tikoo.

A key to the effectiveness of live vaccines is their suitability for intranasal delivery. “Intranasal delivery of live viral vectored vaccines targets the respiratory tract, promoting a stronger and longer immune response over conventional vaccines,” explains Tikoo. “Intranasal delivery also eliminates the needle injection site reaction that can reduce meat quality.”

Besides their potential disease-fighting and meat-quality guarding benefits, live viral vectored vaccines delivered intranasally do not require the strong oil-based adjuvants that the other vaccines require, making them cheaper to produce, he says. “Economic viability of vaccine production is always an important factor in effective vaccine development strategy. We can certainly reach standard targets with these vaccines if everything goes well.”

Other VIDO researchers are also working on intranasal delivery systems that would carry the vaccine antigens.

Considering the economic losses, a cost-effective live vaccine that reduces respiratory and intestinal disease by 50 percent, should have a dramatic impact for the producer bottom line. “The positive effects of this intranasal vaccine will also flow over into the meat processing industry, since injection site reactions would be avoided.”

Support for this research has been received from Alberta Agriculture Research Institute, Saskatchewan Agriculture Development Fund, Saskatchewan Beef Development Fund, Saskatchewan Horned Cattle Trust Fund, Saskatchewan Cattle Marketing Deductions Fund, Manitoba Cattle Producers Association, Kamloops Stockmen’s Association, Natural Science and Engineering Research Council of Canada, Canadian Institute of Health Research, Saskatchewan Health Services Utilization and Research Council, Governments of Manitoba and British Columbia and private sector partners.

VIDO is a not-for-profit research institute specializing in food animal and poultry infectious diseases and is wholly owned by the University of Saskatchewan. It operates with significant support from the Government of Alberta and Government of Saskatchewan.

For more information, contact:

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