Researchers use chicken's immune system as weapon against avian flu

As poultry farms in B.C. recover from the latest outbreak of avian flu in Canada, researchers in the Faculty of Veterinary Medicine are studying how to stimulate the innate immune system of chickens to fight the spread of different viruses, including avian flu.

Nearly a quarter million chickens and turkeys were euthanized in December, after an outbreak of avian flu on 11 poultry farms in B.C. A decade earlier, 17 million chickens, turkeys and other domestic birds were slaughtered in Canada’s most serious outbreak, in which avian flu spread to 42 commercial farms and 11 backyard coups in B.C.’s Fraser Valley.

“The avian influenza viral strains are maintained in wild water fowl species as low-pathogenic, or disease-causing strains,” says Faizal Careem, assistant professor in virology in the Department of Ecosystem and Public Health, Faculty of Veterinary Medicine. “They can contaminate commercial poultry operations through water sources or worker’s clothes if biosecurity measures are not solid, and then evolve into highly pathogenic strains.”  

Most pathogenic viruses enter through the mucous membranes in the host’s respiratory system. How the immune system responds to that invasion will either prevent or establish the viral infection. “It’s imperative to understand the immunological events to identify key innate immune mediators that can be used to control these viral infections.”

Studying three viral strains

Careem’s lab is exploring avian immune responses to three different respiratory viruses. Infectious bronchitis virus is endemic in commercial poultry in Canada and around the world. Infectious laryngotracheitis, a herpes virus, is also endemic in Canadian backyard poultry and globally. Finally, avian influenza, an orthomyxo virus, is considered a foreign animal disease but Canadian poultry is at constant risk.

“I am focusing on injecting innate immune stimulants into the eggs,” he says. “The innate immune responses are very potent and can develop very quickly.” After they inject the eggs with various substances typically encountered in pathogens, the researchers allow the eggs to hatch and then expose the newly-hatched chicks to the viral strains to see if they are protected.

Injecting eggs to protect bird's immune system

“We are injecting the eggs to empower the bird’s innate immune system so that when they hatch and go out to the poultry barn environment they will be protected from whatever pathogens are around in the barn,” says Careem.

The results have been published several times and researchers are considering developing disease control strategies. The work could be one measure used to prevent outbreaks of avian flu in poultry farms.