1. Department of Epidemiology, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599
2. Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60607
3. Carolina Vaccine Institute and Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599