[1] Univ Michigan, Life Sci Inst, Ann Arbor, MI 48109 USA
[2] Rockefeller Univ, Lab Retrovirol, New York, NY 10065 USA
[3] Univ Michigan, Biophys Program, Ann Arbor, MI 48109 USA
[4] Univ Michigan, Dept Chem, Ann Arbor, MI 48109 USA
[5] Rockefeller Univ, Lab Virol & Infect Dis, New York, NY 10065 USA
[6] Univ Michigan, Dept Biol Chem, Ann Arbor, MI 48109 USA
[7] Rockefeller Univ, Howard Hughes Med Inst, New York, NY 10065 USA