1. Department of Microbiology, Oregon State University, Corvallis, Oregon
2. Department of Statistics, Oregon State University, Corvallis, Oregon
3. Gladstone Institutes, San Francisco, California, USA
4. Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, California, USA
5. Department of Epidemiology & Biostatistics, Institute for Human Genetics, and Institute for Computational Health Sciences, University of California, San Francisco, San Francisco, California, USA