1. Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida 32610.
2. Epidemiology Unit, Department of Infectious Parasitic and Immunomediate Diseases, Istituto Superiore di Sanità, Rome, Italy.
3. MRC Bioinformatics Unit, South African National Bioinformatics Institute, University of Western Cape, Cape Town, South Africa.
4. Department of Experimental Medicine, University Roma Tor Vergata, Rome, Italy.
5. National HIV Confirmatory Laboratory—National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria.
6. Hospital of Infectious Diseases, Sofia, Bulgaria.
7. Faculty of Biology, University of Sofia, Sofia, Bulgaria.
8. Ministry of Health, Program of “Prevention and Control of HIV/AIDS,” Sofia, Bulgaria.