[1] Univ Zurich Hosp, Div Infect Dis, CH-8091 Zurich, Switzerland
[2] Univ Zurich Hosp, Dept Med, Inst Clin Immunol, CH-8091 Zurich, Switzerland
[3] Rockefeller Univ, Aaron Diamond AIDS Res Ctr, New York, NY 10021 USA
[4] Univ Hosp Geneva, Div Infect Dis, Geneva, Switzerland