[1] Inst Pasteur, Unite Chim Organ, Dept Biol Struct & Chim, CNRS,URA2128, F-75724 Paris 15, France
[2] Univ Montpellier 1, CNRS, U5048,Ctr Biochim Struct, INSERM,U554, F-34090 Montpellier, France
[3] Univ Montpellier 2, CNRS, U5048,Ctr Biochim Struct, INSERM,U554, F-34090 Montpellier, France
[4] Inst Pasteur, Dept Infect & Epidemiol, Lab Immunotherapie, F-75724 Paris 15, France