Influence of the pre-membrane and envelope proteins on structure, pathogenicity, and tropism of tick-borne encephalitis virus

Abstract

Although an effective vaccine exists, there is no treatment for those infected by the tick-borne encephalitis virus (TBEV). This study aimed to better understand how the virus’s surface proteins influence viral tropism and pathogenicity. We created a chimeric virus with prM and E proteins of TBEV in the genetic background of the low-pathogenic Langat virus (LGTV). The chimeric virus remained low pathogenic, similar to LGTV. Both viruses infected similar brain regions, while TBEV showed a strong preference for the cerebellum and Purkinje cells. This means that other parts of the virus, such as non-structural proteins or NCR, likely decide how the virus behaves in the brain. This study also presents the first cryogenic electron microscopy structure of LGTV, the first whole-brain imaging of TBEV infection in mouse brain, and a new model system to study surface proteins in tick-borne flaviviruses—laying groundwork for future studies on viral tropism, antibody cross-reactivity, and virus-receptor interaction.