Cocktail of recombinant proteins protects cattle against paratuberculosis

Scientists with the USDA’s Agricultural Research Service (ARS) have developed an experimental vaccine to protect cattle from infection with Mycobacterium avium subsp. paratuberculosis (MAP).

Rather than use the cells of live but weakened or dead MAP, as has been done with past commercial vaccine formulations, ARS microbiologists Judy Stabel and John Bannantine set their sights on four proteins from the bacterium, which they discovered from previous research to sequence and characterize its genome.

In preliminary trials, vaccinating mice with the proteins reduced bacterial colonization of the rodents’ intestinal walls and bacterial shedding in faeces, a major route by which other hosts become infected. Cattle, for example, can become infected while grazing pasture where MAP-contaminated manure is located. Calves ingesting colostrum from an infected dam is another route of infection, noted Stabel, who along with Bannantine, is with the ARS National Animal Disease Center’s Infectious Bacterial Diseases Research Unit in Ames, Iowa.

Encouraged by the results with mice, the researchers scaled-up their efforts, using standard laboratory procedures to produce the four proteins and combine them into a single, recombinant vaccine “cocktail” that could be administered to calves.

Throughout, the researchers strived to avoid shortcomings of past vaccine formulations that had been developed, including a tendency to trigger blemishes at the site of injection and interference with the accuracy of serological tests used to detect not only MAP, but also Mycobacterium bovis, the cause of bovine tuberculosis.

Trials with dairy calves are detailed in the journal Vaccine. In addition to rendering the young animals immune to the disease over the course of a year of monitoring, the formulation showed little to no cross-reactivity with serological tests for both paratuberculosis and bovine tuberculosis. Administering the vaccine cocktail also did not trigger blemishes at the injection site, Stabel reported, a potential benefit for animals raised for their meat and hides.

The researchers note the need for additional efficacy trials and say they would welcome collaboration with an industry partner to explore the patented vaccine cocktail’s commercial potential further.

Article: Stabel, J. R., Bannantine, J. P. (2021). Reduced tissue colonization of Mycobacterium avium subsp. paratuberculosis in neonatal calves vaccinated with a cocktail of recombinant proteins. Vaccine, 39(23), 3131-3140, doi: 10.1016/j.vaccine.2021.04.051