1. Mbeya Medical Research Programme, Referral Hospital, Mbeya, Tanzania
2. Department of Infectious Diseases and Tropical Medicine, University of Munich, 80799 Munich, Germany
3. U.S. Military HIV Research Program, Rockville, Maryland 20851
4. Department of Internal Medicine, University of Saarland, 66421 Homburg, Germany
5. Division of Medical Virology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
6. Institute of Virology, University of Saarland, 66421 Homburg, Germany