Research focuses on Johne’s vaccine

Disease prevalent in Alberta | Researchers hope to develop oral vaccine for young calves

University of Calgary researchers are working on a new type of oral Johne’s disease vaccine for calves that may provide immunity.

Oral doses are an improvement over an injection of killed vaccine because they can travel to the spot where the offending bacteria are found in the intestine.

“We believe we need a vaccine that can actually get to that site and get into the tissues and start an immune response that would actually be protective,” said researcher Jeroen De Buck, of the university’s faculty of veterinary medicine.

The vaccine would be given to young calves rather than depending on immunity received in colostrum.

“We don’t believe that antibodies transferred from the dam to the calf would be protective,” he said.

“We need another kind of response from the calf from in the intestine.”

Seventy percent of Alberta dairy farms have Johne’s disease.

Also known as paratuberculosis, Johne’s is a chronic and potentially fatal disease that prevents absorption of nutrients in the intestines of ruminants. The animals eventually starve to death.

No effective vaccines are available so producers have to rely on a high level of biosecurity.

The research, which receives funding from the Alberta Livestock and Meat Agency and Alberta Milk, is looking at creating a live attenuated vaccine, which involves identifying the genes of the bacterium responsible for the infection and deactivating them.

The vaccine genes will contain markers that will help distinguish vaccinated cattle from cattle infected with Johne’s or bovine tuberculosis.

Researchers are also studying all the known strains of the disease in Canada.

“There are different strains, but what we don’t know is if there are actually differences in how they cause disease,” he said.

As well, scientists are working on risk assessments on farms and improving diagnoses.

A three-year surveillance project showed the disease is widespread across Alberta farms, although probably just a few cattle are actually infected in a herd.

“We didn’t know the within-herd prevalence, but we know the prevalence in the province of Alberta,” said Jodi Flaig, industry development co-ordinator at Alberta Milk.

Producers who have a herd with negative results should continue to test their cattle. Positive herds should be monitored every year, and producers need to work with their veterinarian to eliminate it.

Flaig said Alberta Milk has applied for Growing Forward 2 money to continue the Johne’s initiative and conduct risk assessments for other possible diseases.

The Alberta project is part of the Canadian Johne’s Disease Initiative to reduce the prevalence of disease. It is a collaboration led by Dairy Farmers of Canada, the Canadian Cattlemen’s Association and the Canadian Animal Health Coalition.

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