1. Centre for HIV and STIs, National Institute for Communicable Diseases, Johannesburg, Gauteng, South Africa
2. Antibody Immunity Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Gauteng, South Africa
3. Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, KwaZulu-Natal, South Africa