Revealing the viral and cellular determinants of disease outcome in tick-borne encephalitis virus infection

Tick-borne encephalitis virus (TBEV) cases are increasing rapidly due to climate change and the introduction of tick vectors into new geographical areas. Despite this emergence, no effective anti-TBEV therapeutics are available. I previously investigated TBEV pathogenicity using chimeras of strains with a close genetic makeup, but highly variable pathogenic properties (Hypr and Vs strains). Vs causes asymptomatic infections whilst Hypr causes rapid cell death and severe disease. My preliminary data showed that Hypr-non- structural (NS) proteins induce apoptosis and cell death, whilst Vs-NS proteins activate anti-apoptotic proteins to promote the survival of infected cells. The precise viral-host determinants and the mechanisms that dictate the outcome of Hypr and Vs infections were not defined. This proposal will: (i) Identify the precise NS region(s) responsible for TBEV pathogenicity using current and newly developed Vs/Hypr chimeric viruses. (ii) Identify the host proteins/genes that are modulated during viral infection using transcriptomics and co-immunoprecipitation and mass spectrometry analysis. These targets will then be validated using CRISPR/Cas9 knock-outs and drugs. (iii) Understand the specific mechanisms of TBEV persistence in the brain using state-of-the-art nano-resolution imaging techniques, sophisticated in vitro human mini-brain organoids, and BBB-organ models. These experiments will reveal how viral/cellular factors shape the TBEV neuropathogenesis.