©2008 WGBH Ed. Fndn. All Rights Reserved. Animation adapted from Viral Fusion ©2008 Univ. of Massachusetts & XVIVO Scientific Animation. Production:Irene Bosch, Michael Astrachan & David Bolisnky. Animation: Janet Iwasa, Gaël McGill, Digizyme Inc. Composting, editing, & art direction: Michael Astrachan, XVIVO. Narrative & data: Yorgo Modis, Yale Univ. Music production: Alonsound. Acknowledgements: Univ. of Massachusetts Medical School, Emory Univ. School of Medicine, Stanford Univ. School of Medicine, Dana-Farber Cancer Inst., Mount Sinai School of Medicine, Oklahoma Medical Research Fndn., Immunology and Cancer Program, Baylor Inst. for Immunology Research, Cooperative Centers for Translational Research on Human Immunology and Biodefense U19-AI057319, National Inst. of Allergy and Infectious Diseases, NIH. Additional images courtesy; US Dept. of Agriculture & Center for Disease Control and Prevention; James Gathany (photog.), Frank Hadley Collins & Paul I. Howell (content providers).