Preparation of a monoclonal antibody to a hemorrhagic toxin from Prairie rattlesnake (Crotalus viridis viridis) venom: its characteristics and use in isolating the toxin: Charlotte L. Ownby,1Jane Halpern,2 and William H. Habig2 (1Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, U.S.A., and 2Center for Biologics Evaluation and Research, Laboratory of Bacterial Toxins, Division of Bacterial Products, U.S. Food and Drug Administration, Bethesda, MD, U.S.A.)