[1] Columbia Univ, Howard Hughes Med Inst, Coll Phys & Surg, Dept Biochem & Mol Biophys, New York, NY 10032 USA
[2] Chinese Acad Sci, Ctr Infect & Immun, Inst Biophys, Beijing, Peoples R China
[3] Rockefeller Univ, Lab Virol & Infect Dis, New York, NY 10021 USA