Johne’s disease is a challenge for the dairy industry. One of the main issues associated with identifying Johne’s is that the calf gets infected at a young age, but symptoms may not show in the animal for years. Johne’s disease is difficult to diagnose and when present, can cause animal mortality, decreased milk production and financial concerns for producers.

Currently, the dairy industry focuses on disease prevention because there is no reliable, cost-effective method to identify the subclinical carriers of Johne’s disease. University of Alberta Professors Dr. Stephane Evoy and Dr. Christine Szymanski hope to change that. They recently completed a research project that uses bacteriophages and bacteriophage tails to detect Mycobacterium avium paratuberculosis (MAP), the bacteria that causes Johne’s disease.

According to Dr. Evoy, “Bacteriophages are unique viruses that are often used for bacterial typing. If they can identify the bacteria at an earlier stage of Johne’s disease, this could provide great relief to dairy producers.”

The test works when the bacteriophages’ receptor binding proteins (RBPs) found on their tails bind with receptors on the bacteria. Drs. Evoy and Szymanski have also successfully determined that bacteriophages and their recombinant binding proteins can detect bacteria such as E. coli, campylobacter, shigella and salmonella.

Using immobilized bacteriophages, Drs. Evoy and Szymanski discovered an RBP that successfully identified MAP. This opens the door for future research in this area, including the potential creation of a novel single diagnostic test for Johne’s disease. This test would allow for early detection and treatment of the disease. It is estimated that this treatment could save producers $200 per cow per year in a herd with 10 per cent of animals showing clinical signs of Johne’s.

Drs. Evoy and Szymanski would like to thank ALMA and Prairie Diagnostic Services for their support of this project.