1. Department of Biochemistry, Boston University School of Medicine, Boston University, Boston, MA 02118, USA
2. National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, MA 02118, USA
3. Department of Biology, Brandeis University, Waltham, MA 02453, USA
4. Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston University, Boston, MA 02118, USA
5. Genome Science Institute, Boston University School of Medicine, Boston University, Boston, MA 02118, USA