Poster Presentation Asia-Pacific Vaccine and Immunotherapy Congress 2026

mRNA Vaccine Against Japanese Encephalitis Virus Genotype IV Protects Against Lethal Infection (#110)

Abigail L. Cox 1 2 , Wilson Nguyen 1 , Lucy Wales-Earl 3 , Bing Tang 1 , Kexin Yan 1 , Jonathan Peters 4 , Alexander A. Khromykh 5 6 , Romain Tropée 4 , Nigel A.J. McMillan 3 , Andreas Suhrbier 1 5 6 , Daniel J. Rawle 1 5 6
  1. Infection and Inflammation Department, QIMR Berghofer, Brisbane, QLD, Australia
  2. Faculty of Health, Medicine and Behavioural Sciences, The University of Queensland, Brisbane, QLD, Australia
  3. Nanomedicine Biofoundry, Griffith University, Southport, QLD, Australia
  4. Southern RNA Pty Ltd, Southport, QLD, Australia
  5. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
  6. GVN Centre of Excellence, Australian Infectious Disease Research Centre, Brisbane, Queensland, Australia

In 2022 Australia saw an unprecedented outbreak of Japanese encephalitis virus genotype IV (JEV GIV). The outbreak involved 42 human cases with seven fatalities, as well as affecting >80 pig farms in New South Wales and Queensland. Herein we designed, constructed, and tested two JEV GIV mRNA vaccines encoding prME, which provided protection against lethal JEV GIV challenge in an Ifnar-/- mouse model. The vaccines were not codon optimised and included either the Native (full length) or a Shorter signal peptide, with the latter missing the N-terminal n-region. Two vaccinations with 5µg of the Shorter vaccine provided neutralising antibody responses that were significantly lower but overlapped those seen after vaccination with Imojev, a live attenuated vaccine approved for use in humans. Both mRNA vaccines provided ≈ 5-6 log reduction in viraemia, >80% protection against overt disease and weight loss, and mortality. This study illustrates in-country mRNA vaccine generation in response to a local outbreak, with JEV mRNA vaccines potentially emerging to be easier to manufacture, cheaper, and more suitable for immunocompromised individuals.