1. Departamento de Biologia Celular, Molecular e Bioagentes Patogênicos; Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto; FMRP/USP Ribeirão Preto SP 14049-900 Brazil
2. Section of Microbial Pathogenesis; Yale University School of Medicine; New Haven CT 06511 USA
3. International Research Center for Infectious Diseases; Research Institute for Microbial Diseases; Osaka University; Yamadaoka 3-1, Suita Osaka 565-0871 Japan