Feed additive in development to reduce food safety risks

Plant-based vaccine could be less expensive to produce to control E. coli

A researcher checks a bacterial plate count.
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Technology that can produce vaccines and antibodies in plant leaves is being put to work in the livestock industry in hopes of preventing the development of a pathogen that causes food-borne illness in people.

PlantForm Corporation has launched a new research project with Agriculture and Agri-Food Canada (AAFC) and Western University in London to target E.coli infection in pigs, specifically O157:H7, through a feed additive.

Why it matters: O157:H7 is a strain of E.coli that is harmless to most animals but can be dangerous and even deadly to humans. It occurs naturally in the gut of animals like cattle and pigs and is shed into the environment through their manure.

“What we’re trying to do is reduce the prevalence and shedding of E.coli, so the idea is to come up with a feed additive that can be given before slaughter, a powder administered in the feed that is a low-cost solution,” says PlantForm CEO Don Stewart.

Although E.coli O157:H7 is not a new challenge, it made particular headlines in Canada about two decades ago when the town of Walkerton’s water supply became contaminated, causing six deaths and making hundreds more sick.

That helped spur the development of a vaccine for cattle to reduce prevalence of the pathogen in the animals, but it did not see wide uptake. According to the Beef Cattle Research Council, it is not currently available.

E.coli contamination results in expensive – and often extensive — recalls of meat products, but can also cause food safety issues in produce if vegetables in the field come into contact with water containing the pathogen.

PlantForm’s vivoXPRESS platform uses genetically modified tobacco plants to ‘grow’ biopharmaceuticals (plant-based antibodies and vaccines), making it a faster and more cost-effective alternative to the commonly used fermentation systems for biopharmaceutical production. It’s technology originally developed at the University of Guelph by one of PlantForm’s founders, Chris Hall.

Dr. Rima Menassa is a research scientist in plant biotechnology at AAFC in London, who has developed plant-based bovine antibodies that prevent E.coli’s ability to colonize in the gut wall.

With this new project, she is looking to prove her concept in animals, starting with mice trials and then moving into pigs. Although O157:H7 is more commonly associated with cattle, it is carried by pigs and she hopes the outcomes will be easier to accomplish on monogastric or single stomach animals like pigs, where digestion is a faster and simpler process than in ruminant animals.

Pig uptake could be simpler than ruminants

“We are hoping that with pigs, who have only one stomach and digestion taking two to four hours, the antibodies can pass through and get to the intestine without being degraded. It is more complicated with ruminants, so we decided to take the first step in a pig and then maybe go to ruminants,” she explains.

The goal is to see whether the antibodies that work in the lab setting will translate to animals, both in preventing O157:H7 from growing in the gut and in preventing shedding if an animal already has the pathogen.

This new, two-year project is supported through the Ontario Ministry of Agriculture, Food and Rural Affairs’ Ontario Agri-Food Research Initiative, which is funded by the Canadian Agricultural Partnership. It is part of wider efforts to find low-cost, practical ways to prevent infection and transmission of pathogens that impact human and animal health.

Although this is work with a food safety focus, Menassa and PlantForm are also working on a project with direct animal health implications — a vaccine for Porcine Epidemic Diarrhea virus (PEDv). It causes severe dehydration and diarrhea in pigs, and although older animals can recover, the virus is generally fatal in young piglets.

“The idea is to vaccinate pregnant sows, so they generate the antibodies that are transferred to the piglets and they in turn become protected,” says Stewart.

The first case of PED in Ontario was identified in January 2014 and since then, the industry has been actively working to manage and ultimately eliminate the disease from the province.

According to Menassa, the PED project is still in early stages, but if early results are promising, she hopes to move into a study with pigs later this year.

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