1. Institutes of Microbiology, Università Cattolica del Sacro Cuore, Largo F. Vito, 1, 00168 Rome, Italy
2. Infectious Diseases, Università Cattolica del Sacro Cuore, Largo F. Vito, 1, 00168 Rome, Italy
3. Public Health Research Institute, New Jersey Medical School, UMDNJ, Newark, New Jersey