1. Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, UFRJ, 21941-902 Rio de Janeiro, Brazil
2. Department of Molecular Genetics & Microbiology, Stony Brook University, 145 Life Sciences Building, Stony Brook, 11794 NY, USA
3. Veterans Administration Medical Center, Northport, 11768 NY, USA