Breakthrough seen in testing for bovine TB

VIDO-InterVac at the University of Saskatchewan is evaluating a diagnostic tool to quickly test for the disease in bison

Trials are underway in Saskatchewan using unique diagnostic tools to test for bovine tuberculosis in bison.

Actiphage by PBD Biotech is being evaluated as an improved detection method for the disease at VIDO-InterVac at the University of Saskatchewan.

The two organizations have teamed with Parks Canada to conduct trials on bison from Wood Buffalo National Park in Alberta and the Northwest Territories.

“Bison are an important reservoir for the disease and we’re developing vaccines for them,” said Volker Gerdts, director at VIDO-InterVac.

He said fast diagnosis is critical to control TB in cattle as well as in bison.

“This is an example of a rapid test and it allows rapid decision making. In the last outbreak we saw ranchers have to wait for a long time before they knew whether they had to buy feed for their animals or whether they were allowed to trade them or not,” he said.

Bovine TB affected several southeastern Alberta cattle herds in 2016 and several more in central British Columbia in 2018. Animals in herds with TB positive individuals are typically destroyed to contain disease spread.

Since then, the Actiphage blood test has been successfully tested in humans and on 20 species of animals but never before on bison.

It can be used to quickly and accurately detect low levels of TB-causing mycobacteria in a blood sample.

“What we’ve done with the Actiphage is really developed a platform that very efficiently isolates the DNA for the mycobacterium,” said Luis Martin from PBD Biotech.

“We’ve got a sensitivity now down to under 10 cells and a couple of milligrams of blood. You get results in a single day and you only have to test the animals once.”

As well, he said the technology is able to differentiate between animals that are vaccinated and those that are infected, which creates the potential to vaccinate animals and protect them from the disease.

“We only pick up living bacteria, so an active infection, whereas some of the assays don’t distinguish between living and dead bacteria. An animal may be over the infection but still test positive. So you get false results that way as well,” he said.

Quick test results will enable early detection and improved disease management. The new method is also more accurate compared to existing methods.

PBD Biotech, which is based in the United Kingdom, has chosen Saskatoon to set up its first international subsidiary office.

Bison are currently in VIDO-InterVac’s containment Level 3 facility where they have been infected with a laboratory strain of TB at different doses and variable times.

Benchmarking will show the progression of the disease in bison and reliability of the tests.

“Once that knowledge is there of how the model works, then we will go back next January with a fresh group of bison and vaccinate them with the new vaccines. Then we will infect them, challenge them with what’s the appropriate dose of bovine TB,” said Martin.

Another test will determine if vaccines proven effective in cattle can also protect bison.

“The immune system in cattle and bison are actually not that similar so you cannot automatically assume that a vaccine for cattle also works in bison,” said Gerdts.

However, the disease can spread from bison to cattle.

“If we had vaccines to control TB in bison we would reduce that risk. In order to do that we need to have good diagnostic tests,” he said.

Detecting tuberculosis in livestock and wild animals is a global issue and an outbreak can be devastating to the agricultural industry.

Worldwide, it’s one of the biggest challenges facing the cattle industry with estimates of more than 50 million infected cattle costing about $3 billion annually.

“If we come up with a vaccine, you’ll actually be able to take preventive measures. And then if you put the vaccine together with the Actiphage diagnostic, you have a very nice complement because one of the issues with vaccinating animals, or humans for that matter, is that the vaccine generates an immune response,” said Martin.

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