1. Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
2. Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, Canada
3. Department of Pediatrics, Faculty of Medicine, Dalhousie University and the IWK Health Centre, Halifax, NS, Canada
4. Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax, NS, Canada
5. Current address: Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA