Fatemeh (Darya) Fazel, University of Guelph

Fatemeh (Darya) Fazel1, Janan Shoja Doost1, Ali Tolooe1, Maya Dayoub1, Shahriar Behboodi2,3, Sarah Wootton1, Shayan Sharif1* 1Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, N1G 2W1, Canada. 2Bristol Veterinary School, University of Bristol, Langford BS40 5DU, United Kingdom 3Avian Immunology Group, The Pirbright Institute, Pirbright, Woking, Surrey GU24 0NE, United Kingdom

Fighting & Responding

Avian influenza virus (AIV) continues to pose a significant threat to both the poultry industry and public health. mRNA lipid nanoparticle (LNP) vaccines provide a rapid and efficient platform for addressing influenza virus outbreaks and pandemics due to their scalable, egg-free production process. In this study, we developed a bivalent mRNA-LNP vaccine encoding the hemagglutinin (HA) and neuraminidase (NA) proteins of the H9N2 avian influenza virus. The immunogenicity of 8 μg of modified mRNA administered with toll-like receptor (TLR) 3 and 21 ligands was evaluated by assessing antibody- and cell-mediated immune responses, as well as virus shedding. To measure post-vaccination and post-challenge responses, immunoglobulin (Ig) M and Y levels, interferon (IFN)-γ production, splenocyte proliferation, IFN-γ and interleukin (IL)-2 gene expression, and the 50% tissue culture infectious dose (TCID₅₀) were assessed. The IgM and, IgY levels were significantly higher in mRNA vaccine groups at different time points. In addition, the result of cell proliferation assay as well as production of (IFN)-γ by spleen cells re-stimulated in vitro demonstrate the induction of both antibody- and cell-mediated immune responses in vaccinated chickens which corresponds with lowered virus shedding in the mRNA vaccinated birds. Overall, the result of this study demonstrated that two doses of the vaccine were well tolerated in chickens and induced both antibody- and cell-mediated immune responses, resulting in reduced virus shedding in the vaccinated groups.