Kathleen Fulton, University of Manitoba

Kathleen Fulton (1,2), Jérémie Prévost (1), David Safronetz (1,2) Affiliations: 1. Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada. 2. Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada.

Fighting & Responding

Monkeypox virus (MPXV) is the causative agent of mpox, a viral febrile rash illness. MPXV belongs to the Orthopoxvirus genus, and is closely related to variola virus which is responsible for smallpox. Historically, MPXV was confined to endemic regions of Western and Central Africa, but recently, this virus spread across the world, impacting approximately 170,000 people in over 100 countries since 2022. Currently, a repurposed smallpox vaccine called Modified Vaccinia Ankara (MVA) is approved for use against MPXV in Canada, however, this vaccine has issues such as limited supply and distribution, suboptimal efficacy, and unfavourable immunogenicity. These issues provide critical reasoning for the development of an improved vaccine. Subunit protein vaccines are advantageous due to their enhanced safety, efficacy and simple manufacturing making them an ideal candidate for an improved vaccine against MPXV. In this study, we assessed the immunogenicity of seven immunodominant MPXV antigens (A27, A29, A35, B6, E8, H3, and M1) using a QS-21-adjuvanted formulation. Mice were vaccinated with monovalent vaccines to examine the humoral and cellular immune responses following prime-boost vaccination with each protein. Six of the antigens provided excellent serum IgG endpoint titres, ranging from 10^5 to 10^6. Future studies will be conducted to assess protection of monovalent and multivalent vaccines in a lethal MPXV mouse model, with a direct comparison against the currently approved vaccine. Overall, this study aims to create a multivalent vaccine that will provide better immunogenicity and protection, with minimal supply or safety concerns.