1. Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
2. Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
3. Department of Biosciences, Paris Lodron University of Salzburg, Salzburg, Austria
4. Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA