1. P. Cossart is with the Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris, France,.
2. P. Boquet is with INSERM, U452, Faculté de Médecine, 06107 Nice, France. S. Normark is with Karolinska Institute, Microbiology and Tumor Biology Center, S10401 Stockholm, Sweden.
3. R. Rappuoli is with Istituto Ricerche Immunobiologiche, IRIS, 53100 Siena, Italy.