1. 1Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, Nebraska 68583-0905;
2. 2Seccion de Bacteriología, Corporacion para Investigaciones Biologicas (CIB), Carrera 72A No. 78B 141, A.A. 7378, Medellín, Colombia
3. 3Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon 97331;