1. Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
2. Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
3. Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
4. Division of Infectious Disease, Department of Pediatrics, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA