1. Dysplasia Department Instituto Nacional de Cancerología Mexico City Mexico
2. Laboratory of Virus and Cancer Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México & Instituto Nacional de Cancerología Mexico City Mexico
3. Department of Obstetrics and Gynecology Boston University Chobanian and Avedisian School of Medicine Boston Massachusetts USA
4. Anal Neoplasia Clinic, Research, and Education Center University of California San Francisco San Francisco California USA
5. Basic Research Unit, Virus, and Cancer Laboratory Instituto Nacional de Cancerología Mexico City Mexico
6. Infectious Diseases Department Instituto Nacional de Cancerología Mexico City Mexico
7. Department of Surgical Pathology Instituto Nacional de Cancerología Mexico City Mexico