Molekulare Charakterisierung der Hepatitis-C-Virus-Zellmembran-Interaktion
Zusammenfassung der Projektergebnisse
Cellular binding and entry of HCV is the first step of virus-host cell interaction. Since this step represents a critical determinant of tissue tropism and pathogenesis, it is a major target for host cell responses - such as antibody-mediated virus-neutralization - and a promising target of antiviral therapy. Using novel model systems for the study of the first steps of viral infection, we have defined viral and host cell factors mediating HCV binding and entry into hepatocyte-derived cell lines and hepatocytes. These include the characterization of highly sulfated heparan sulfate as a novel liver cell surface molecule mediating docking of the viral envelope to the cell surface membrane and scavenger receptor BI (SR-BI) as a host factor for hepatitis C virus infection required for an entry step closely linked to CD81. Furthermore, using a model system based on HCV-like particles, we demonstrated that SR-BI plays an important role for HCV uptake and cross-presentation in human dendritic cells. These studies indicate that SR-BI may not only represent a host entry factor but also plays an important role in HCV recognition by the host cell. Extending these functional studies identifying and characterizing HCV host cell entry factors, we analyzed host cell responses induced by HCV binding and entry. For many viruses, virus-host interaction resembles a two-way dialogue in which the virus takes advantage of the cell’s own signal transduction systems to transmit signals to the cells. Using a genomic analysis of responses following binding of HCV-like particles and recombinant envelope glycoproteins (E1/E2) to hepatoma cells, we demonstrated that binding of HCV envelope glycoproteins to host cells results in a cascade of intracellular signals modulating cellular gene expression, which may condition the cell for support of viral propagation. These changes include modulation of lipid metabolism and innate immune responses. Using a genomic analysis of the liver transcriptome in liver biopsies of HCV-infected and control individuals, we could demonstrate that several of these observed responses are present during HCV infection in vivo. Viral entry has an important clinical impact since it is a major target of host neutralizing responses. Thus, a major recent focus has been the study of antibody-mediated HCV neutralization and its impact for pathogenesis of HCV infection. Using an infectious retroviral HCV pseudo-particle model system, we studied a cohort of women accidentally exposed to the same HCV strain of known sequence. In this single-source outbreak of hepatitis C, viral clearance was associated with a rapid induction of neutralizing antibodies in the early phase of infection. Neutralizing antibodies decreased or disappeared following recovery from HCV infection. In contrast, chronic HCV infection was characterized by absent or low-titer neutralizing antibodies in the early phase of infection and persistence of infection despite the induction of cross-neutralizing antibodies in the late phase of infection. These data suggest that rapid induction of neutralizing antibodies during the early phase of infection may contribute to control of HCV infection. This finding may have important implications for understanding of the pathogenesis of HCV infection and the development of novel preventive and therapeutic antiviral strategies. Taken together, these results have defined cellular and viral structures mediating HCV-cell surface interaction and identified targets for antiviral immune responses. Identification and characterization of the cell surface molecules required for viral binding and entry may ultimately result in a complete molecular understanding of the viral life cycle and in novel antiviral strategies (development of HCV entry inhibitors). The molecular dissection of mechanisms of antibody-mediated virus neutralization will be a key feature for the design of effective vaccine approaches and the prevention of HCV re-infection during liver transplantation.
Projektbezogene Publikationen (Auswahl)
- APOBEC-mediated interference with hepadnavirus production. Hepatology, 2005, 42,301-309
Rösler, C., Köck, J., Blum, H. E., Baumert, T. F., Weizsäcker, F.
- Hepatitis B virus mutations associated with fulminant hepatitis induce apoptosis in primary Tupaia hepatocytes. Hepatology, 2005, 41 , 247-256
Baumert, T. F., Yang, C., Schürmann, P., Köck, J., Liang, T. J., Nassal, M., Blum, H. E., von Weizsäcker, F.
- Scavenger receptor class B type I and hepatitis C virus infection of primary tupaia hepatocytes. Journal of Virology, 2005, 79, 5774-5785
Barth, H., Raffaele, C, Mirko, A., Schürmann, P., Zhao, X., Adah, M. I., Gißler, B., von Weizsäcker, F., Blum, H. E., Vitelli, A., Scarselli, E., and Baumert, T. F.
- Uptake and presentation of hepatitis C virus-like particles by human dendritic cells. Blood, 2005, 105, 3605-3614
Barth, H., Ulsenheimer, A., Diepolder, H., Pape, G. R, Paranhos-Baccala, G., Depla, E., Blum, H. E., Baumert, T. F.
- Dominant influence of an HLA-B27 restricted CD8+ T cell response in mediating HCV clearance and evolution. Hepatology, 2006, 43, 563-572
Neumann-Heafelin, C., Spangenberg, H. C., Nazarova, N., Baumert, T. F., Weizsäcker, F., Blum, H. E., Thimme, R.
- Entry of hepatitis C virus pseudotypes into primary human hepatocytes by clathrin-dependent endocytosis. Journal of General Virology, 2006, 87, 2583-2593
Codran, A., Royer, C., Jaeck, D., Bastien-Valle, M., Baumert, T. F., Kieny, M.-P., Pereira C. A., Martin, J. P.
- Host cell responses induced by hepatitis C virus binding. Hepatology, 2006, 43, 1326- 1336
Fang, X., Wilpert, J., Barth, H., Gissler, B., Kreutz, C., Donauer, J., Weizsäcker, F. v., Blum, H. E., Baumert, T. F.
- Viral and cellular determinants of hepatitis C virus envelope-heparan sulfate interaction. Journal of Virology, 2006, 80, 10579-10590
Barth, H., Schnober, E. K., Zhang, F., Linhardt, R. J., Depla, E., Boson, B., Cosset, F. L., Patel, A. Blum, H. E. and Baumert, T. F.
- CD81 expression is important for the permissiveness of Huh7 cell clones for heterogeneous hepatitis C virus infection. Journal of Virology, 2007, 81, 5036-45
Akazawa D., Date T., Morikawa K., Murayama A., Miyamoto M., Kaga M., Barth H., Baumert T.F., Dubuisson J., Wakita T.
- Hepatitis B Virus DNA is subject to extensive editing by the human deaminase APOBEC3C. Hepatology, 2007, 46, 682-689
Baumert T.F., Rosler C., Malim M., Weizsacker F.
- Immunization of chimpanzees with hepatitis C virus-like results in control of hepatitis C virus infection in chimpanzees. Proc Natl Acad Sci. USA, 2007, 104, 8427-32
Elmowalid, G., Qiao, M., Jeong, S., Baumert, T.F., Sapp, R., Hu, Z., Murthy, K., Liang T..J.
- Rapid induction of virus-neutralizing antibodies and viral clearance in a single-source outbreak of hepatitis C. Proc Natl Acad Sci USA. 2007, 104, 6025-6030
Pestka, J.M., Zeisel, M.B., Bläser, E., Schürmann, P., Bartosch, B., Cosset, F.L., Patel, A.H., Meisel, H., Baumert, J., Viazov, S., Rispeter, K., Blum, H.E., Roggendorf, M., Baumert, T.F.
- Scavenger receptor class B type I is a key host factor for hepatitis C virus infection required for an entry step closely linked to CD81. Hepatology, 2007, 46, 1722-1731
Zeisel, M. B., Koutsoudakis, G., Schnober, E. K., Haberstroh, A., Blum, H.E., Cosset, F.L., Wakita, T., Jaeck, D., Doffoel, M., Royer, C., Soulier, E., Schvoerer, E., Schuster, C., Stoll-Keller, F., Bartenschlager, R., Pietschmann, T., Barth, H., Baumert, T.F.
- Tracking virus-specific CD4+ T cells during and after acute hepatitis C virus infection. PLOS one, Jul 25, 2007, 2:e649
Lucas, M., Ulsenheimer, A., Pfafferot, G., Heeg, M.H.J., Gaudieri, S., Gruner, N., Rauch, A., Gerlach, J.T., Jung, M.C., Zachoval, R., Pape, G.R., Santantonio, T., Nitschko, H., Obermeier, M., Phillips, R., Scriba, T.J., Semmo, N., Day, C., Weber, J.N., Fidler, S., Thimme, R., Haberstroh, A., Baumert T.F., Klenerman, P., Diepolder, H.M.
