About the Authors

Jonathan D. Stoltzfus

Affiliations Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America, Department of Biology, Hollins University, Roanoke, Virginia, United States of America

Stephen M. Bart

Affiliation Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America

James B. Lok

jlok@vet.upenn.edu

Affiliation Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: JDS JBL. Performed the experiments: JDS SMB. Analyzed the data: JDS JBL. Wrote the paper: JDS SMB JBL.