Biodefense : next steps : hearing before the Subcommittee on Bioterrorism and Public Health Preparedness of the Committee on Health, Education, Labor, and Pensions, United States Senate, One Hundred Ninth Congress, first session, on examining the biodefense research program of the National Institutes of Health, focusing on the development of medical countermeasures against a bioterrorist attack, February 8, 2005.