[1] NIAID, NIH, Vaccine Res Ctr, Bethesda, MD 20892 USA
[2] Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm 17177, Sweden
[3] Swedish Inst Infect Dis Control, Solna 17182, Sweden
[4] Erasmus MC, Natl Influenza Ctr, NL-3015GE Rotterdam, Netherlands
[5] Erasmus MC, Dept Virol, NL-3015GE Rotterdam, Netherlands
[6] Scripps Res Inst, Dept Immunol, La Jolla, CA 92037 USA
[7] Scripps Res Inst, Dept Mol Biol, La Jolla, CA 92037 USA
[8] Harvard Univ, Sch Med, Div AIDS, Dana Farber Canc Inst,Dept Cancer Immunol & AIDS, Boston, MA 02115 USA