A team of Alberta researchers has developed a poultry vaccine that can protect against a little known but common type of food poisoning — campylobacter jejuni.
“Reported infections of campylobacter in Canada outnumber all the well-known causes of bacterial food poisoning including salmonella, shigella, listeria, and toxigenic E. coli combined,” said Christine Szymanski, CEO of VaxAlta Inc., which created the vaccine.
“If you ask most people, they’ve heard of E. coli, salmonella, and listeria, because those pathogens are typically associated with outbreaks. Campylobacter is mostly associated with sporadic cases of infection so it never makes it into the news, but it’s a huge problem worldwide.”
In developed countries like Canada, infection by C. jejuni is “usually self-limiting” — which means the situation usually resolves itself without treatment, said Szymanski, who is also a professor at the University of Alberta.
But in developing countries, C. jejuni is one of the leading causes of morbidity and mortality.
“C. jejuni is highly prevalent,” she said. “It’s found contaminating the surfaces of most sources of poultry, but there are no product recalls as you see with other bacteria, like E. coli and listeria.
“And, even if a product tests positive for campylobacter, there is currently no measure to control it. But once we have a vaccine available that is effective, this would help the regulatory bodies to put restrictions on the levels of campylobacter that are allowed to be on poultry products.”
This is the first vaccine that has shown any promise against C. jejuni, which has no effect on its poultry hosts but causes diarrhea in humans, said Szymanski.
“There have been multiple attempts by other researchers to develop vaccines against C. jejuni that have shown limited success,” she said.
“We’re excited by the large drops in C. jejuni colonization that we observed in chickens.”
This vaccine, which should hit the market in the next two years, is also the first glycoconjugate — or sugar-based — vaccine developed for use in livestock.
“Sugars coat every living cell, and bacteria are notorious for making unique sugars that we don’t possess,” said Szymanski.
“Several successful glycoconjugate vaccines have been created for use in humans, especially as part of childhood vaccination programs. But the problem with large-scale production of these glycoconjugate vaccines is that they are too expensive to be used in livestock.”
In order to get around that, Szymanski’s team has used weakened carriers, like harmless strains of E. coli, to produce the necessary bacterial sugars that will “generate good immune responses and eliminate the pathogen of interest.”
“That allows us then to immunize chickens with an inexpensive vaccine that provides protection,” she said.
“And because our vaccine carrier is eliminated prior to the time for chicken slaughter and the gut bacteria in the chicken are not altered, the glycoconjugate vaccine is safe for use in food animals.”
This is an “unexploited niche” for VaxAlta, which is also working on livestock vaccines for other types of foodborne pathogens.
“The glycoengineering approach is a platform technology for us,” said Szymanski. “The C. jejuni vaccine is one of our first-generation glycoconjugate vaccines, but we’re quite far advanced in making other poultry vaccines against relevant foodborne pathogens. Clostridium perfringens is one of these pathogens that we’re targeting because it causes necrotic enteritis in chickens and food poisoning in humans.
“Our end goal is to create safe livestock vaccines that will eliminate the use of antibiotics.”