Vaccine Cocktail Could Protect Cattle from Disease

Agricultural Research Service scientists say they have a way to protect cattle from the bacterium that causes Johne’s disease, Mycobacterium avium subsp. paratuberculosis (MAP). The experimental vaccine cocktail showed promising results in trials.

Johne’s disease is a chronic intestinal disorder that can cause diarrhea, weight loss, poor health and sometimes death in cattle afflicted with it. It is also known as paratuberculosis. Johne’s disease is more often seen in dairy herds, rather than beef herds. Researchers estimate more than $220 million in annual losses to the industry.

Cattle aren’t the only ones affected by Johne’s disease. It also affects other ruminants, being seen in sheep, goats and deer.

Here is what the two agricultural research microbiologists did. They broke from the traditional method of creating commercial vaccine formulations using the cells of live but weakened or dead MAP. Instead, they worked with four proteins discovered in previous research sequencing the bacterium’s genome

The Agricultural Research Service microbiologists Judy Stabel and John Bannantine conducted preliminary trials in which they vaccinated mice with the proteins. They observed reduced bacterial colonization of intestinal walls and bacterial shedding in feces of the mice. The scientists say feces are a major route by which other hosts can pick up the infection.

It has been shown that cattle grazing pasture where MAP-contaminated manure is located, can become infected. There are onflow effects too, as calves can get the infection passed to them through ingesting colostrum from an infected dam, Judy Stabel says.

The Vaccine Cocktail

Stabel and Bannantine were so encouraged by these results that they used standard laboratory procedures to produce the four proteins adding them into a single, recombinant vaccine cocktail. Their aim was to administered the vaccine cocktail to calves in 200 or 400 microgram doses.

Previous efforts at creating vaccine formulations has shortcomings, including sometimes triggering blemishes at the injection site and interfering with the accuracy of serological tests for various bacteria.

Dairy Calf Trials

Positive outcomes from the dairy calf trials were detailed in the April 2021 issue of the journal Vaccine. The trials showed that the vaccine cocktail gave the young animals immunity to the disease over the course of a year of monitoring. In addition, it solved one of the shortcomings of previous formulations, adding no cross-reactivity with serological tests for either Johne’s disease or bovine tuberculosis.

“Administering the vaccine cocktail also did not trigger blemishes at the injection site, “ Stabel reported.

The researchers say that additional efficacy trials are needed for the patented vaccine cocktail. They are looking to collaborate with an industry partner to explore the vaccine cocktail’s commercial potential.

Stabel and Bannantine are based at the Agricultural Research Service National Animal Disease Center’s Infectious Bacterial Diseases Research Unit in Ames, Iowa.