1. Department of Biological Sciences; University of Toronto at Scarborough; Toronto; ON; M1C 1A4; Canada
2. Ontario Agency for Health Protection and Promotion; Toronto; ON; M9P 3T1; Canada
3. Department of Microbiology and Immunology and Department of Medicine - Division of Infectious Diseases; Dalhousie University; Halifax; NS; B3H 1X5; Canada