[1] San Raffaele Sci Inst, DIBIT, AIDS Immunopathogenesis Unit, P2 P3 Labs, I-20132 Milan, Italy
[2] San Raffaele Sci Inst, DIBIT, Biostat Unit, I-20132 Milan, Italy
[3] CHU Vaudois, Div Infect Dis, Lab AIDS Immunopathogenesis, CH-1011 Lausanne, Switzerland
[4] San Raffaele Sci Inst, San Luigi AIDS Ctr, Div Infect Dis, I-20132 Milan, Italy
[5] Maggiore Hosp, A Bianchi Bonomi Hemophilia & Thrombosis Ctr, Ist Ricovero & Cura & Carattere Sci, Milan, Italy
[6] Univ Milan, Milan, Italy
[7] Calif Dept Hlth Serv, Berkeley, CA 94704 USA
[8] Walter Reed Army Inst Res, Div Retrovirol, Dept Mol Diagnost & Pathogenesis, Rockville, MD USA