About the Authors
Division of Infectious Diseases, Veterans Affairs Medical Center and the University of California, San Francisco, California, United States of America
Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
University College, Dublin, Ireland
The authors have declared that no competing interests exist.
Conceived and designed the experiments: HSS RS ASB PMS. Performed the experiments: HSS YQX JM RS. Analyzed the data: HSS ASB. Contributed reagents/materials/analysis tools: ASB PMS. Wrote the paper: HSS PMS.