Project 1: Vaccine Design Neurotropic Flaviviruses

SUMMARY Emerging and re-emerging arthropod-vectored viruses pose a significant threat to human health. Tick- and mosquito-transmitted viruses can cause encephalitis and hemorrhagic fever leading to significant morbidity and mortality. West Nile virus (WNV), tick-borne encephalitis virus (TBEV), and Zika virus (ZIKV) all have tropism for

neuronal cells, which can lead to infection and injury in the central nervous system. Several emerging and re- emerging neurotropic flaviviruses represent a growing health concern due to their epidemic potential. New rational immunogen design strategies are necessary to elicit protective responses that confer durable protection

against current and future flavivirus threats. Project 1 of our Flavivirus and Alphavirus ReVAMPP (FLARE) Center uses iterative immunogen design cycles to develop, optimize, and advance next-generation vaccine candidates using WNV and TBEV as prototype neurotropic flaviviruses. Our approaches focus on the major

surface envelope (E) glycoprotein, and we hypothesize that the structural conservation of the E glycoprotein will enable a ‘plug and play’ modular workflow of immunogen and vaccine platform pairs that can be deployed for other emerging or re-emerging neurotropic flaviviruses. In Aim 1, we design protein-based nanoparticles for

multivalent display of E-subdomains, E-DI and E-DIII. In Aim 2, we use protein engineering strategies to covalently and non-covalently stabilize E dimers to display complex, conformation-specific epitopes present on the virion that are the target of potently neutralizing and protective immune responses. In Aim 3, we implement

two immune-focusing strategies, epitope scaffolding and hyperglycosylation, to elicit responses to conserved E- DIII epitopes. Initial down-selection will occur using protein-based immunogens with some candidates advancing to mRNA-based delivery with our industry partner, Moderna. Vaccine candidates will be tested for

immunogenicity, antigenicity, and immune focusing with optimal candidates advancing to protection studies using lethal WNV and TBEV murine challenge models in Aim 4. After down-selection and rigorous Go/No-Go decision criteria, the top vaccine candidates will be transitioned to Animal Core D for further evaluation in mice

and non-human primates. Project 1 will work closely with Structural Core C to accomplish these objectives and is conceptually and scientifically linked to FLARE Projects 2 and 3, which are focused on endemic flaviviruses and alphaviruses, respectively.