Shayan Sharif’s latest research on necrotic enteritis (NE) takes two different approaches to controlling the disease and one of its key causal agents, Clostridium perfringens. He’s identified new strains of probiotic bacteria and created a new NE vaccine, and is now hoping to discover added synergy by combining them.
Dr. Sharif, associate dean of research and graduate studies, Ontario Veterinary College at the University of Guelph, is leading a large research project investigating the use of beneficial microbes to improve poultry health, as researchers continue exploring antibiotic alternatives in Canadian poultry production. “We know that birds with a healthier gastrointestinal tract are less likely to allow pathogenic bacterial infections,” says Sharif.
The big picture for the multi-disciplinary project is to look for ways to mitigate the risk of NE in broiler production. It’s a disease that primarily concerns broilers, but NE can also impact the layer industry and possibly turkeys.
For Sharif’s piece of the puzzle, he’s looking at the use of beneficial microbes (probiotics) in the poultry gut and also looking to create better vaccines against NE. There are currently no approved NE vaccines registered in Canada.
Probiotics are well recognized in their role to improve gut health, boost immunity and arm birds with a stronger defense against pathogens. Sharif and his research team by isolating more than 50 strains of lactobacilli – beneficial microbes that are naturally occurring in the bird’s gut and identified which would be more efficacious against C. perfringens.
In the first part of their research, they used several strains of lactobacilli to evaluate the ability of the microbes to reduce the risk of infection from C. perfringens. The probiotic cocktail was administered orally to young birds before they were challenged with C. perfringens and they then measured the amount of the pathogen in the bird’s gut, in addition to severity of necrotic enteritis. “We found that if we gave young birds the lactobacilli before they were exposed to C. perfringens, there was a significant reduction in the amount of C. perfringens and a significant reduction in the clinical severity of the disease,” says Sharif.
The second part of the project involved developing a new vaccine for NE to test in the lab and in a semi-commercial setting at the University of Guelph’s Arkell Research Station. “Like any vaccine, we are trying to boost immunity to disease by using the bird’s own immune system to mount a response against C. perfringens in order to protect itself from the pathogen.”
To test the new NE vaccine, they used a different beneficial microbe (lactococcus) to deliver the vaccine. Like the lactobacilli strains used in the probiotic, lactococcus is also a beneficial microbe that has been used for the delivery of recombinant vaccines to several species, including mammals and birds.
“Lactococcus delivers its cargo – the antigens against C. perfringens – into the bird’s gut and at some point is cleared from the gut. But we found that this probiotic delivery mechanism could also have some beneficial effect against C. perfringens in the bird.”
Young birds were inoculated orally with the lactobacilli-based vector vaccine and then challenged with C. perfringens. They found that inoculation can help boost the bird’s immune response to protect it from NE, as measured by a reduction in gut lesions and an improvement in the intestinal mucosa.
Both strategies for controlling NE brought similar, encouraging results. “We found that we can indeed reduce the risk of NE in poultry using both beneficial microbes and with vaccines, and results from both approaches were quite comparable,” says Sharif. Those findings are feeding into the third and final part of the five-year study.
“What we want to do now is combine the two probiotics that were used separately in the first part of this project – lactobacilli in the probiotic and lactococcus in the vaccine – put them both in the gut and see if they synergize to multiply the impact of these two approaches to controlling NE,” say Sharif. “Hopefully in about a year’s time, we’ll have the answer to this part of the project.”
The question of when new antibiotic alternatives like these could be commercially available is anyone’s guess. Sharif is confident that they have two safe and efficacious products – one in the form of a beneficial microbe and one in the form of a vaccine. “We have done our lab testing and the next level would be to take these products to commercial testing,” says Sharif. “But it’s really the interest of the industry that drives the next steps towards commercialization.”
He’s hopeful that with all the testing they have done on these new options for mitigating the risk of NE from C. perfringens that producers don’t have to wait for years before we could see these products in the market.