Could a bacterium’s clever trick benefit horses?

Bacillus thuringiensis under 1000X magnification. Image: Dr Sahay/Wikipedia
Bacillus thuringiensis under 1000X magnification. Image: Dr Sahay/Wikipedia

Bacillus thuringiensis is a soil-dwelling bacterium that ekes out a simple existence, but scientists say it has a trick up its sleeve that could prove of immense benefit to horses.

It produces a protein molecule called Cry5B that researchers hope may ultimately prove effective in killing parasites in the gut of horses.

That would be great news for horses and their owners.

Equine parasitologist Martin Neilsen hopes horse owners will back an innovative bid to raise cash for worm research.
Equine parasitologist Martin Neilsen hopes horse owners will back an innovative bid to raise cash for worm research.

There have been no newcomers among commercial deworming products for horses in years, and all are prone to some level of resistance from equine parasites.

B. thuringiensis could ultimately be the genesis of a probiotic wormer – a product that would be welcomed by the growing number of horse owners determined to keep things natural

Equine parasitologist Martin Nielsen stresses there is a long way to go from a substance that shows promise as a dewormer to something which is proven safe and suitable for wider use.

Nielsen has added another twist to the research, seeking funding for the project through an online crowdfunding campaign.

Crowdfunding is usually the domain of company startups and political campaigns, but Nielsen hopes that horse owners who see merit in the benefits of a probiotic dewormer will step on board to help.

Nielsen, an assistant professor at the University of Kentucky’s Gluck Equine Research Center, said he decided a while ago that he wanted to try crowdfunding as a means to meet the costs of research, and decided the B. thuringiensis project was an ideal candidate.

The campaign, entitled “Let the germs get the worms”, is possibly the first research project in the field of veterinary science to seek backing through crowdfunding.

Want to contribute to the research into Bacillus thuringiensis? You can do so here. The project website is here
Follow the sign up link, which will allow you to ask questions about parasite control, read more about the research project, and stay up-to-date with progress.

The campaign is well on the way to its first modest target of $US5000, with $US4250 raised at the time writing. But Nielsen hopes the campaign will gather momentum and ultimately reach $US30,000 as word spreads. And who knows what could be reached if the early laboratory tests show especially promising results?

But Nielsen says crowdfunding is only part of it. The campaign had generated a lot of publicity and focused a lot of attention on his work.

“I didn’t know what to expect,” he said of the crowdfunding strategy.

“We are making people aware in the horse industry of who we are and what we do,” he said, adding that it was in many ways more valuable than the money raised.

The campaign is supported by a website, where people interested in the project can register. They can then ask questions about parasite control, read more about the research project, and stay up-to-date with progress.

Nielsen said the public had been welcoming of the campaign and what he and his collaborator, Raffi Aroian, from the University of California, were trying to achieve.

So what have other scientists made of the untraditional funding approach?

“The feedback has been very positive,” Nielsen said. “A lot have said, ‘this is a great idea. It’s innovative. It’s great to see someone trying something different.”

© Martin Nielsen
© Martin Nielsen

Some scientists, he said, were considering trying it out in some fashion in the future. And several have supported the campaign financially.

“I feel there has been interest and acceptance. I wasn’t sure how this would be received at first. I was not sure if the scientific community would accept this as another way for raising research funding.”

Nielsen said he had seen discussions elsewhere involving criticism of such a funding model, with the main thrust being that science should not be a popularity contest. But in his view, it can never be bad if the public gains an interest in a certain project.

“In my field of horse research, we don’t have a great deal of access to grants from large government agencies,” he explains.

There is some industry funding, but this goes only so far. The issue was then coming up with other ways to raise research funding, he explains.

So, what of B. thuringiensis? Nielsen said he thought research into the bacterium had real potential to garner popular support, given that any potential deworming product developed would be a probiotic, appealing to those who were unsure about the so-called chemical dewormers.

“This was a project where I could tell an appealing story,” he said. The story was clear, simple, and the goals easy to define for the general public.

Veterinary science has four classes of dewormers available to kill parasites in horses, the oldest dating back about 50 years. Some are proving far less effective these days, due to resistance, and some work against only some parasites, or on parasites during only certain phases of their life cycles.

Even the “rock stars” among dewormers – the broader ivermectin-based family known as the macrocyclic lactones – are gradually falling victim to growing parasite resistance.

There has not been a new family of equine dewormers in more than 30 years.

Nielsen said no new drugs were currently being developed for use in parasite control in horses, so the equine industry needed new and reliable treatment alternatives.

He said the soil-dwelling B.thuringiensis at the center of the research was not traditionally part of any probiotic, for animals or people.

Research to date has shown that the protein crystals produced by the bacterium were capable of killing intestinal worms, seemingly without causing problems for the host.

There is already some good data available on its use in pigs, hamsters and mice, with good results, he said.

“The whole concept of the protein produced by this bacterium is not new,” he said. “It is also used now as a non-chemical pesticide in organic farming.”

The first part of the collaborative study aims to evaluate the effect of this bacterial protein against important horse parasites under laboratory conditions. Preliminary results have already proved encouraging.

The next phase will involve much more thorough testing of the bacterium and its protein crystals in petri dishes in the laboratory against the common equine parasites.

This will give Nielsen and his colleagues a handle on how effective the protein crystals are in killing the parasites, and will also allow them to determine what dose will be necessary for effective deworming.

“We expect to use the results to apply for a larger grant to finally allow us to test the probiotic in horses,” he said

This will be the much costlier and more complex phase. The research in this phase will not only involve assessing whether the bacterium works in a horse’s gut, as opposed to a laboratory. It will also have to assess precisely how effective it is, monitor the animals carefully for any adverse effects, and determine whether the bacteria have any effects on the crucial balance of gut bacteria needed for horse digestion.

Nielsen anticipates that any probiotic developed would not contain the bacterium itself, as stomach acid would quickly degrade the given dose.

He expects the probiotic would comprise the spores of the bacterium, which could successfully pass through the acidic stomach, then develop into the bacteria in the gut and produce the parasite-killing protein crystals. It may, he said, be necessary to add some other “good” bacteria to the probiotic to assist in maintaining a healthy balance in the gut.

Nielsen stressed that even if the long path to a viable deworming probiotic proved successful, it would still have to be used correctly.

Even though of natural origin, it would still be prone to the development of parasite resistance. Just how quickly that would occur is a matter of guesswork at this stage.

“Biologically, we can’t expect to develop any modality in which worms cannot develop some resistance. Chemical or non-chemical, there will always be an active ingredient to which parasites can develop resistance.”

Any probiotic would be the same boat as any other dewormer, he said.

“We will have to be careful not to overuse it.”

Visit the project website here.



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