Structure-guided optimization of immunogens for emerging arthropod-borne viruses

Thesis

Mosquito-borne arboviruses, such as flaviviruses and alphaviruses cause millions of infections every year and raise public health concerns worldwide, yet, there are no approved vaccines or specific treatments for the majority of them. There is also an urgent need for improved diagnostics and intervention methods to tackle these. This thesis aims to contribute to improved diagnostics and intervention methods focused against flaviviruses (Zika and Dengue) and alphaviruses (Chikungunya and Mayaro) by improving serological diagnostic tools, testing of new vaccine candidates or discovery of new drug targets based on both immunological and structural studies. In the first and second chapter, the production and purification of flaviviruses envelope (E) and non-structural (NS1) glycoproteins in mammalian cell culture along with that of envelope glycoprotein of alphaviruses are described. These reagents are used for immunomonitoring of arboviral vaccines in both, pre-clinical and clinical studies, in particular for ChAdOx1 Zika and Chikungunya vaccine candidates under Phase I clinical trials. These chapters detail the development of ELISA-based serodiagnosis of ZIKV, DENV and CHIKV using volunteers’ sera from an endemic region in Mexico. In addition, these chapters describe the assessment of immunogenicity and efficacy of MVA based Zika vaccine candidates and the ChAdOx1 based CHIKV vaccines. In the third chapter and the final chapter, the expression and characterisation of alphavirus virus-like particles (VLP) are described for structural studies coupled to immunogenicity and efficacy studies, using in vivo and in vitro approaches. Progress has been made on the determination of their cryo-EM structures to understand its glycan structural targets and interactions with the host-cell receptors such as MXRA8. Finally, future plans are discussed for the production of monoclonal antibodies against MAYV and CHIKV using hybridomas for further Cryo-EM study of MAYV VLP–MAYV specific or CHIKV cross-reactive neutralising mAb to reveal the critical epitopes to understand and design structural guided vaccines against alphaviruses.

Authors: Kim, YC

• DOI: 10.5287/ora-zbmk6krkw
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English