About the Authors
Environmental Health Sciences, School of Public Health, University of Alberta, Edmonton, Alberta, Canada
Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: PCH ESL. Performed the experiments: PCH MAF. Analyzed the data: PCH MAF. Contributed reagents/materials/analysis tools: ESL. Wrote the paper: PCH ESL.