1. Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
2. Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
3. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
4. Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA