Early research into potential probiotic worming agent shows promise

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

Crowdfunded research into what scientists hope may lead to the development of a probiotic wormer has delivered promising early results.

“It’s really good news,” said equine parasitologist Martin Nielsen, with the Gluck Equine Research Center at the University of Kentucky.

Nielsen spearheaded an innovative crowdfunding campaign to raise money for research into the potential of a crystal protein produced by a soil-dwelling bacterium, Bacillus thuringiensis, to kill equine parasites.

The crowdfunding campaign, more conventionally the domain of company startups, raised more than $US9000 and donations continue to come in.

Some of the money had now been spent, said Nielsen, yielding positive results.

“We cultured strongyle parasite larvae in the lab and exposed them to different doses of the protein that our bacteria are secreting.

“Here at the university we have a population of parasites that has never been treated with any type of dewormer, and another one that is resistant to two out of three drug classes. We tested our bacterial protein against both of these parasite strains.”

The research showed that the crystal proteins secreted by these bacteria were effective in killing both drug-naive and drug-resistant parasites. The research also provided some information on what concentrations were needed to be effective.

Equine parasitologist Martin Neilsen says early results of his crowdfunded research are positive.
Equine parasitologist Martin Neilsen says early results of his crowdfunded research are positive.

“Obviously, we are very excited about these results,” he said.

“Our plan is now to include this data in a research grant application which we will be submitting to the US Department of Agriculture later this month.

“If we get the funding, we will move on to the next phase of this project, which involves testing the bacteria and their protein product in horses.”

The protein molecule produced by Bacillus thuringiensis is called Cry5B.

Nielsen and his collaborator, Raffi Aroian, from the University of California, hope that 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.

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

There has not been a new family of equine dewormers in more than 30 years, and all are prone to some level of resistance from equine parasites.

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.

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 B.thuringiensis 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.”

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 stresses 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.”

The website behind the project can be viewed here


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