1. Department of Microbiology and Immunology, Albert Einstein College of Medicine; Bronx NY USA
2. Department of Biochemistry, Netherlands Cancer Institute; Amsterdam The Netherlands
3. Department of Microbiology and Immunobiology, Harvard Medical School; Boston MA USA
4. Virology Division, US Army Medical Research Institute of Infectious Diseases; Fort Detrick MD USA
5. Department of Biochemistry, Stanford University School of Medicine; Stanford CA USA
6. Department of Microbiology and Immunology, Stanford University School of Medicine; Stanford CA USA