About the Authors
Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: GWL LZ. Performed the experiments: GWL LZ. Analyzed the data: GWL LZ. Contributed reagents/materials/analysis tools: GWL LZ. Wrote the paper: GWL LZ.