Rational Engineering and Immunological Evaluation of Coxsackievirus B1 Virus-Like Particle Vaccines

<b>Background:</b> Enteroviruses are common human pathogens that cause a broad range of diseases ranging from mild infections to severe acute and chronic conditions. Although there are over a hundred distinct enterovirus types infecting humans, licensed vaccines are currently available only against the three polioviruses and enterovirus A71. Because of their extensive type diversity and global circulation, there remains a strong need for the development of novel, safe and broadly applicable enterovirus vaccines. Virus-like particles (VLPs) represent a promising vaccine platform due to their structural similarity to native viruses combined with the absence of viral genetic material. <b>Methods: </b> This doctoral thesis used rational design and comprehensively characterised engineered coxsackie B1 (CVB1) VLP vaccine candidates. CVB1 VLPs were produced using a baculovirus-insect cell expression system and two different modified VLPs were produced by deleting selected capsid regions hypothesised to be unbeneficial for protective immunity. The VLPs were characterised using multiple methods that analysed the particle structure, purity and biochemical properties. Immunogenicity of VLPs was assessed in several mouse studies including determining the optimal dose, administration schedule, evaluating different administration routes and use of adjuvant as well as protective efficacy in a challenge study. <b>Results: </b> Modified CVB1-VLPs had significantly improved production yields compared to the unmodified VLP, and the 2-5 years stability studies demonstrated exceptional stability at +8°C. Immunisation studies showed that all VLP vaccines elicited strong humoral responses despite the removal of selected capsid regions and adding an adjuvant improved cellular immune response significantly. The removal of unbeneficial capsid regions resulted in avoiding immune responses towards those regions. <b>Conclusions: </b> This work demonstrated that rational capsid engineering of CVB1-VLPs is a viable strategy, substantially enhancing the manufacturability, while maintaining the immunogenicity for the vaccines. Particularly when adjuvanted, modified VLPs offer promising approach for developing safe and effective enterovirus vaccines.