Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA.