New vaccine for bovine tuberculosis uses probiotics to survive the gut

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Researchers across various universities are developing a new vaccine and delivery system to prevent bovine tuberculosis (TB) in free-roaming white-tailed deer—a primary reservoir for the disease. The development is a mucosal, oral, probiotic-based vaccine that may contribute to the eradication of bovine TB in any wildlife species.¹

“Controlling bovine TB in animals with vaccination is a primary approach to preventing or mitigating the spread of a disease across animal populations and into human populations,” Srinand Sreevatsan, BVSc, MVSc, MPH, PhD, associate dean for research and graduate studies in the College of Veterinary Medicine at Michigan State University (MSU) and lead of the research team, said in a news release by MSU.¹ “Here in Michigan, the rise in bovine TB-infected deer and cattle herds has led to a state of urgency due to restrictions associated with animal trade and movement.”

The mucosal vaccine was designed to withstand the intestinal mucosal barrier, which works to prevent pathogens from entering the body. Prior to the new vaccine, the development of oral vaccines had been hindered due to the inhospitable environment of the gut, according to the release.¹ Sreevatsan and his teammates, Srinivas Dhandayuthapani, PhD, at the Center of Emphasis in Infectious Diseases at Texas Tech University Health Sciences Center, and Gireesh Rajashekara, DVM, PhD, at the Ohio State University, Center for Food Animal Health, used Bacillus subtilis spores, a probiotic naturally found in fermented foods and soil, as well as in the gastrointestinal tract of humans and ruminants, such as deer.^1,2 B subtilis is capable of withstanding the acidic environment of the gut and its protective mucosal barrier. It can also survive the conditions of the outdoors food bait it will be left in for deer to ingest, according to the news release.¹

“Using probiotic spores to deliver antigens is a very exciting development,” said Sreevatsan.¹ “We clone the bovine TB antigen encoding genes in the genetic machinery of Bacillus subtilis, and program it to express those antigens when they make spores.”

The current vaccine used to protect against TB—the Bacillus Calmette-Guérin (BCG) vaccine—is not effective in its prevention of illness in ruminants, including cattle, white tail deer, and other animals.¹ Moreover, according to MSU, the BCG vaccine does not protect against the spread of bovine TB.¹

“There’s a need for a vaccine that can be delivered to deer as well as cattle,” he continued.¹ “We require a low-cost vaccine and delivery system that will work with animals in the wild, and one that will actually provide a robust immune response.”

The potential of the B subtilis-based vaccine

The new bovine TB vaccine project, which received a grant from the United States Department of Agriculture, has the potential of being engineered to protect other wildlife animals against any infectious disease, such as the highly pathogenic H5N1 avian influenza, due to the flexible nature of the vaccine’s delivery mechanism—which is similar to a nanoparticle delivery system.¹

“With this platform, we are producing a machinery of specialist suppliers that isn’t limited to bovine TB antigens. We’re very optimistic about its ability to deliver vaccines for any infectious disease,” said Sreevatsan.¹

References

1. MSU researchers vaccinating animals in the wild to combat TB, infectious diseases. Michigan State University. News release. June 28, 2024. Accessed July 8, 2024. https://msutoday.msu.edu/news/2024/msu-researchers-vaccinating-animals-in-the-wild-to-combat-tb-infectious-diseases
2. Bacillus Subtilis – Uses, side effects, and more. WebMD. Accessed July 8, 2024. https://www.webmd.com/vitamins/ai/ingredientmono-1694/bacillus-subtilis