1. Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA.
2. Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
3. Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA.
4. Departments of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan.