[1] Univ Duisburg Essen, Univ Hosp Essen, Inst Virol, D-45147 Essen, Germany
[2] Univ Hosp Essen, Dept Gastroenterol & Hepatol, D-45147 Essen, Germany
[3] Goethe Univ Frankfurt Am Main, Univ Hosp, Inst Med Virol, D-60590 Frankfurt, Germany
[4] DZIF, German Ctr Infect Res, D-38124 Braunschweig, Germany