1. Centre for the AIDS Programme of Research in South Africa (CAPRISA), Durban;
2. Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada;
3. MRC-CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Doris Duke Medical Research Institute, University of KwaZulu-Natal, Durban, South Africa; and
4. Department of Epidemiology, Columbia University, New York