Researchers are trying to develop a vaccine that can be slipped into a calf without having to pierce the skin and pollute a muscle with serum.
The result, scientists at the Veterinary Infectious Diseases Organization say, could be more effective vaccines and less damage from injection site lesions – a problem the beef industry estimates costs Canadian farmers tens of millions of dollars per year.
“If you have the immunity right at the site of infection, then we have a better chance of protecting against (infection),” said VIDO research scientist Dale Godson.
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Godson and other researchers at the Saskatoon-based organization think vaccines sprayed into animals’ noses or digested in their stomachs would be more effective than ones now injected under the skin and into muscles.
Most germs for problems like scours get into animals through the lungs or the digestive system.
Normal vaccines injected into muscle tissue provoke the animal’s immune system to create antibodies that spread from the injection site into the bloodstream and attack infections after they are established elsewhere in the body.
If a vaccine can be sent right to the lungs or digestive system, the antibody concentration there would be high, and the infection itself might be prevented, said Godson.
Non-needle vaccines such as sprays and pills have been developed and used before. The polio vaccine for humans is an example.
But VIDO isn’t looking at a simple chemical nose spray or pill. It is investigating the possibility of using one living microorganism to deliver weapons the animal needs to fight other microorganisms.
“We’re using a virus to deliver our vaccine to the animal,” said Godson.
Researchers hope they can genetically engineer the adnovirus, a virus that exists in 80 to 90 percent of prairie cattle and causes no problems, to carry both antigens for disease and biological boosters that will make the animal’s immune system react strongly.
They hope to do this by splicing some DNA from a disease germ and some DNA from the immune system booster into the adnovirus. This altered virus can then be sent into an animal through a spray or pill, they think.
Once the altered virus is there, it will multiply in the animal and spread the antigen of the disease, which is not infectious, throughout its digestive system or lungs.
Griebel said most vaccines now rely on dead organisms that provoke only a slight response from the immune system.
Molecular biologist Maria Baca-Estrada said using the virus and natural immune boosters should be more effective than using synthetic chemicals.
“It’s using nature’s own way of working,” said Baca-Estrada.
Godson just received $120,000 from Saskatchewan’s Agriculture Development Fund to investigate whether Interleukin 6 can be used as an effective immune booster in living vaccines.
Godson said his project will take up to three years. Coming up with an altered virus vaccine system that is commercially viable and is approved by government could take 10 to 15 years.
