http://hdl.handle.net/10033/56880 Leiter: Prof. T. Pietschmann Wed, 22 May 2013 12:30:44 GMT 2013-05-22T12:30:44Z http://hdl.handle.net/10033/288482 Title: Hepatitis C virus NS5B polymerase primes innate immune signaling. Authors: Gerold, Gisa; Pietschmann, Thomas Fri, 01 Mar 2013 00:00:00 GMT http://hdl.handle.net/10033/288482 2013-03-01T00:00:00Z http://hdl.handle.net/10033/283033 Title: Anti-infective properties of epigallocatechin-3-gallate (EGCG), a component of green tea. Authors: Steinmann, J; Buer, J; Pietschmann, T; Steinmann, E Abstract: The consumption of green tea (Camellia sinensis) has been shown to have many physiological and pharmacological health benefits. In the past two decades several studies have reported that epigallocatechin-3-gallate (EGCG), the main constituent of green tea, has anti-infective properties. Antiviral activities of EGCG with different modes of action have been demonstrated on diverse families of viruses, such as Retroviridae, Orthomyxoviridae and Flaviviridae and include important human pathogens like human immunodeficiency virus, influenza A virus and the hepatitis C virus. Furthermore, the molecule interferes with the replication cycle of DNA viruses like hepatitis B virus, herpes simplex virus and adenovirus. Most of these studies demonstrated antiviral properties within physiological concentrations of EGCG in vitro. In contrast, the minimum inhibitory concentrations against bacteria were 10-100-fold higher. Nevertheless, the antibacterial effects of EGCG alone and in combination with different antibiotics have been intensively analysed against a number of bacteria including multidrug-resistant strains such as methicillin-resistant Staphylococcus aureus or Stenotrophomonas maltophilia. Furthermore, the catechin EGCG has antifungal activity against human-pathogenic yeasts like Candida albicans. Although the mechanistic effects of EGCG are not fully understood, there are results indicating that EGCG binds to lipid membranes and affects the folic acid metabolism of bacteria and fungi by inhibiting the cytoplasmic enzyme dihydrofolate reductase. This review summarizes the current knowledge and future perspectives on the antibacterial, antifungal and antiviral effects of the green tea constituent EGCG. Fri, 01 Mar 2013 00:00:00 GMT http://hdl.handle.net/10033/283033 2013-03-01T00:00:00Z http://hdl.handle.net/10033/270512 Title: Subcellular localization and function of an epitope-tagged p7 viroporin in hepatitis C virus-producing cells. Authors: Vieyres, Gabrielle; Brohm, Christiane; Friesland, Martina; Gentzsch, Juliane; Wölk, Benno; Roingeard, Philippe; Steinmann, Eike; Pietschmann, Thomas Abstract: The hepatitis C virus (HCV) viroporin p7 is crucial for production of infectious viral progeny. However, its role in the viral replication cycle remains incompletely understood, in part due to the poor availability of p7-specific antibodies. To circumvent this obstacle, we inserted two consecutive hemagglutinin (HA) epitope tags at its N terminus. HA-tagged p7 reduced peak virus titers ca. 10-fold and decreased kinetics of virus production compared to the wild-type virus. However, HA-tagged p7 rescued virus production of a mutant virus lacking p7, thus providing formal proof that the tag does not disrupt p7 function. In HCV-producing cells, p7 displayed a reticular staining pattern which colocalized with the HCV envelope glycoprotein 2 (E2) but also partially with viral nonstructural proteins 2, 3, and 5A. Using coimmunoprecipitation, we confirmed a specific interaction between p7 and NS2, whereas we did not detect a stable interaction with core, E2, or NS5A. Moreover, we did not observe p7 incorporation into affinity-purified virus particles. Consistently, there was no evidence supporting a role of p7 in viral entry, as an anti-HA antibody was not able to neutralize Jc1 virus produced from an HA-p7-tagged genome. Collectively, these findings highlight a stable interaction between p7 and NS2 which is likely crucial for production of infectious HCV particles. Use of this functional epitope-tagged p7 variant should facilitate the analysis of the final steps of the HCV replication cycle. Fri, 01 Feb 2013 00:00:00 GMT http://hdl.handle.net/10033/270512 2013-02-01T00:00:00Z http://hdl.handle.net/10033/270312 Title: Mutations that alter use of hepatitis C virus cell entry factors mediate escape from neutralizing antibodies. Authors: Fofana, Isabel; Fafi-Kremer, Samira; Carolla, Patric; Fauvelle, Catherine; Zahid, Muhammad Nauman; Turek, Marine; Heydmann, Laura; Cury, Karine; Hayer, Juliette; Combet, Christophe; Cosset, François-Loïc; Pietschmann, Thomas; Hiet, Marie-Sophie; Bartenschlager, Ralf; Habersetzer, François; Doffoël, Michel; Keck, Zhen-Yong; Foung, Steven K H; Zeisel, Mirjam B; Stoll-Keller, Françoise; Baumert, Thomas F Abstract: The development of vaccines and other strategies to prevent hepatitis C virus (HCV) infection is limited by rapid viral evasion. HCV entry is the first step of infection; this process involves several viral and host factors and is targeted by host-neutralizing responses. Although the roles of host factors in HCV entry have been well characterized, their involvement in evasion of immune responses is poorly understood. We used acute infection of liver graft as a model to investigate the molecular mechanisms of viral evasion. Sun, 01 Jul 2012 00:00:00 GMT http://hdl.handle.net/10033/270312 2012-07-01T00:00:00Z