[1] NIAID, Infect Dis Lab, NIH, Bethesda, MD 20892 USA
[2] Copenhagen Univ Hosp, Dept Infect Dis, Copenhagen Hepatitis Program CO HEP C, Hvidovre, Denmark
[3] Copenhagen Univ Hosp, Clin Res Ctr, Hvidovre, Denmark
[4] Univ Copenhagen, Fac Hlth Sci, Dept Int Hlth Immunol & Microbiol, DK-1168 Copenhagen, Denmark
[5] Univ Cagliari, Dept Biomed Sci & Technol, I-09124 Cagliari, Italy
[6] Univ Turin, Dept Pediat, I-10124 Turin, Italy
[7] Univ Roma La Sapienza, Dept Pediat, Rome, Italy
[8] Univ Roma La Sapienza, Dept Clin Med, Rome, Italy
[9] Univ Naples Federico II, Dept Pediat, Naples, Italy