RResponsible for avian flu, the H5N1 virus regularly causes devastation in populations of wild and farmed animals. Recent cases have been detected in marine mammals, cattle and even pigs. Having the potential to trigger a pandemic, H5N1 is also one of the most dangerous viruses for humans. Although transmission between individuals remains rare, the mortality rate exceeds 50% among infected people. “If a mutation allows transmission from human to human, you can imagine the chaos,” underlines Denis Archambault, veterinary doctor and professor of virology and immunology at the University of Quebec in Montreal (UQAM).
After years of research, a vaccine formula could transform the fight against this highly pathogenic virus. It was developed by Denis Archambault and his colleague, Steve Bourgault, biochemist and holder of the Canada Chair in the chemistry of biological nanoassemblies, in collaboration with various laboratories in Canada and France. Published in September 2024 in the journal NPJ Vaccinestrials show that the vaccine completely protects chickens, without any mortality or transmission of the virus. Never seen before.
Traditional flu vaccines typically trigger an immune response against hemagglutinin, a protein on the surface of the virus. The problem is that the latter has an unfortunate tendency to mutate frequently; it is therefore necessary to regularly adapt the vaccine using the latest strain in circulation.
The team of Denis Archambault and Steve Bourgault instead selected a more stable molecule of the virus: a portion of the M2 protein, which changes little over time. It is therefore found almost unchanged from one viral strain to another, but it is insufficient to trigger a strong immune response in animals.
To get around this obstacle, scientists have designed an unstoppable assembly. They attached multiple copies of M2 to nanoparticles that enhance the immune response and added copies of hemagglutinin. “This combination makes it possible to strongly amplify the specific immune response against M2,” explains Steve Bourgault. In addition, the vaccine was deliberately manufactured from a viral strain distant from the strain used to infect vaccinated poultry, which suggests a broad spectrum of protection for different variants of the virus. A potential universal vaccine against avian flu, in a way.
-At the same time, researchers have developed another vaccine based on a similar model based on nanofilaments, designed to be administered nasally. By neutralizing viruses as soon as they enter the respiratory tract, this vaccine could effectively prevent diseases such as influenza or COVID-19, both in humans and animals. Successfully tested on mice against influenza, this intranasal vaccine takes advantage of nanoparticles to replace the adjuvant which generally hinders the development of this type of vaccine.
“The vaccine could be a small spray sold in pharmacies,” suggests Steve Bourgault. “In poultry farms, such a vaccine could be administered more easily by nebulizers diffusing a fine mist,” adds Denis Archambault.
Their commercialization is not imminent, but the two vaccines could be crucial weapons in stopping avian flu and other infections with pandemic potential.
Also participated in these discoveries:
Avian flu vaccine : Vinay Khatri (UQAM); the National Center for Foreign Animal Diseases (Winnipeg) ; the Public Health Agency of Canada; the University of Saskatchewan and the National Research Institute for Agriculture, Food and the Environment (France).
Vaccin intranasal : Philippe St-Louis, Clément Martin and Vinay Khatri (UQAM).
