[1] Duke Univ, Med Ctr, Duke Clin Res Inst, Div Gastroenterol, Durham, NC 27707 USA
[2] Heidelberg Univ, Dept Mol Virol, Heidelberg, Germany
[3] Univ Paris 12, Hop Henri Mondor, Dept Virol, F-94010 Creteil, France
[4] Univ Paris 12, Hop Henri Mondor, INSERM, U635, F-94010 Creteil, France