[1] Sanofi Pasteur, Marcy Letoile, France
[2] Acambis, Cambridge, MA USA
[3] Univ Texas Med Branch, Dept Pathol, Ctr Biodef & Emerging Infect Dis, Sealy Ctr Vaccine Dev, Galveston, TX 77555 USA
[4] Univ Texas Med Branch, WHO, Collaborating Ctr Trop Dis, Galveston, TX 77555 USA