1. Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
2. St. Petersburg AIDS Center, St. Petersburg, Russia.
3. Department of Infectious Diseases, Botkin's Infectious Diseases Hospital, St. Petersburg, Russia.
4. Complejo Hospitalario Provincial de Pontevedra, Pontevedra, Spain.
5. WHO-UNAIDS, Geneva, Switzerland.