1. California National Primate Research Center, University of California, Davis, Davis, CA 95616, USA.
2. Department of Medical Microbiology and Immunology, University of California, Davis, Davis, CA 95616, USA.
3. Division of Gastroenterology, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
4. Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California, San Francisco, San Francisco, CA 94143, USA.
5. Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.