Preclinical Evaluation of a Canadian-Produced H5N1 Vaccine for Pandemic Preparedness

Avian influenza (H5N1) continues to pose a serious global health threat due to its high mortality and growing evidence of mammal-to-mammal transmission. Because the Canadian population has little pre-existing immunity to H5N1, a strain capable of efficient human spread could have devastating pandemic consequences. Effective countermeasures to prevent infection and mitigate severe disease are critical. A key determinant of viral infectivity is the hemagglutinin (HA) surface protein, which mediates viral entry into host cells and is the primary target of neutralizing antibodies. As demonstrated during the COVID-19 pandemic, messenger ribonucleic acid (mRNA) vaccines can generate strong immune responses and can be quickly designed and manufactured at scale in response to an emerging outbreak. In partnership with a Canadian biotechnology company, our lab is evaluating a new mRNA vaccine that encodes the H5 HA from circulating H5N1 viruses. This vaccine is designed to elicit systemic immune responses essential for preventing infection and reducing disease severity. We will assess this by vaccinating mice and measuring immune responses in the blood, lungs, and spleen. This will examine how effectively the vaccine stimulates antibodies and immune cells capable of recognizing and neutralizing the H5N1 virus. To determine the protective effect of the vaccine, vaccinated and control mice will be infected with a lethal dose of H5N1. We will monitor survival and measure both the virus in the lungs and the extent of lung tissue damage. Given the growing threat posed by H5N1, this work will provide critical preclinical evidence to advance a homegrown mRNA vaccine candidate toward clinical development and strengthen Canada's readiness for a potential influenza pandemic.