1. Department of Infectious Disease and Microbiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania, USA
2. Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
3. Center for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
4. Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison Wisconsin, USA
5. Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA