1. U.S. Food and Drug Administration, Center for Biologics Evaluation and Research, Office of Blood Research and Review, Department of Emerging and Transfusion Transmitted Diseases, Laboratory of Bacterial and Transmissible Spongiform Encephalopathy Agents, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
2. Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (CISA-INIA), 28130 Valdeolmos, Madrid, Spain