1. Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, México
2. Present address: Department of Biochemistry and Molecular Biology, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada.
3. Present address: Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.
4. Present address: Institut Pasteur, Department of Immunology, Unit of Antibodies in Therapy and Pathology, Paris, France.