Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.|Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.|Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.|Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.|Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3.