Influence of the pre-membrane and envelope proteins on structure, pathogenicity, and tropism of tick-borne encephalitis virusLaboratory of Emerging Viral Infections, Veterinary Research Institute, Brno, Czech Republic; Faculty of Science, Masaryk University, Brno, Czech Republic; Laboratory of Arbovirology, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic.
Laboratory of Emerging Viral Infections, Veterinary Research Institute, Brno, Czech Republic; Faculty of Science, Masaryk University, Brno, Czech Republic; Laboratory of Arbovirology, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic; Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic.
Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
Department of Infectious Diseases, Institute of Biomedicine at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Proteomics Core Facility, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Department of Infectious Diseases, Institute of Biomedicine at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
Laboratory of Emerging Viral Infections, Veterinary Research Institute, Brno, Czech Republic; Faculty of Science, Masaryk University, Brno, Czech Republic; Laboratory of Arbovirology, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Ceske Budejovice, Czech Republic.
Faculty of Biological and Environmental Sciences, Molecular and Integrative Bioscience Research Programme, University of Helsinki, Helsinki, Finland; Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
Institute of Bioengineering, University of Tartu, Tartu, Estonia.
Faculty of Biological and Environmental Sciences, Molecular and Integrative Bioscience Research Programme, University of Helsinki, Helsinki, Finland; University of Helsinki, Helsinki Institute of Life Sciences-Institute of Biotechnology, Helsinki, Finland; Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
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2025 (English)In: Journal of Virology, ISSN 0022-538X, E-ISSN 1098-5514, Vol. 99, no 9, article id e00870-25Article in journal (Refereed) Published
Abstract [en]
Tick-borne encephalitis virus (TBEV) is a neurotropic flavivirus that causes thousands of human infections annually. Viral tropism in the brain is determined by the presence of necessary receptors, entry factors, and the ability of the virus to overcome host defenses. The viral structural proteins, pre-membrane (prM), and envelope (E) play an important role in receptor binding, membrane fusion, particle maturation, and antibody neutralization. To understand how these proteins influence virus distribution and tropism in the brain, we generated a chimeric virus harboring the prM and ectodomain of E from TBEV in the background of the low-pathogenic Langat virus (LGTV). We solved the atomic structures of both the chimeric virus and LGTV to compare them to the known TBEV structure. We show that this chimeric virus remains low-pathogenic, while being structurally and antigenically similar to TBEV. Using 3D optical whole brain imaging combined with immunohistochemistry, we found that both LGTV and the chimeric virus primarily infect the cerebral cortex, with no significant differences in their localization or tropism. In contrast, TBEV shows high infection of the cerebellum and a strong preference toward Purkinje cells, indicating that factors other than the prM and E proteins are important for determining TBEV tropism in the brain. Together, this provides new insights into the roles of the structural and non-structural proteins of tick-borne flaviviruses. IMPORTANCE: 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.
Place, publisher, year, edition, pages
American Society for Microbiology, 2025. Vol. 99, no 9, article id e00870-25
Keywords [en]
chimera virus, cryo-EM structure, Langat virus, tick-borne encephalitis, viral pathogenesis, whole brain imaging
National Category
Microbiology in the Medical Area Infectious Medicine
Identifiers
URN: urn:nbn:se:umu:diva-245358DOI: 10.1128/jvi.00870-25ISI: 001552231800001PubMedID: 40827915Scopus ID: 2-s2.0-105016811768OAI: oai:DiVA.org:umu-245358DiVA, id: diva2:2005510
Funder
Umeå UniversitySwedish Research Council, 2018-05851Swedish Research Council, 2020-06224The Kempe Foundations, SMK-1654The Kempe Foundations, JCK-18272025-10-102025-10-102025-10-10Bibliographically approved