1. 1Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida 32611, USA
2. †Present address: Department of Neurology, Brigham and Women’s Hospital, Boston, Massachusetts 02115, USA.
3. ‡Present address: Department of Biomedical Sciences, University of New England, Biddeford, Maine 04005, USA.
4. 2The J. Craig Venter Institute, La Jolla, California 92037, USA