1 Laboratory of Microbiology and Virology, Vita-Salute San Raffaele University, Milan, Italy.
2 Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States.
3 Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy.
4 International Agency for Research on Cancer (IARC), World Health Organization, Lyon, France.