1. Department of Computational Medicine and Bioinformatics, University of Michigan Medical School , Ann Arbor, Michigan 48109 , USA
2. Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks , North Dakota 58202 , USA
3. Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine , Baltimore, MD 21201 , USA
4. Unit for Laboratory Animal Medicine, Department of Microbiology and Immunology, Center for Computational Medicine and Bioinformatics, University of Michigan Medical School , Ann Arbor, Michigan 48109 , USA