1. Department of Microbiology; Immunology and Molecular Genetics; University of California; Los Angeles CA 90095 USA
2. Department of Chemistry and Biochemistry; University of California; Los Angeles CA 90095 USA
3. California NanoSystems Institute; University of California; Los Angeles CA 90095 USA
4. Department of Medicine; University of Virginia Health Sciences Center; Charlottesville VA 22908 USA
5. Molecular Biology Institute; University of California; Los Angeles CA 90095 USA