About the Authors

Vivek Naranbhai

Current address: Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom

Affiliations CAPRISA – Centre for the AIDS Programme of Research in South Africa, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa

Marcus Altfeld

Affiliations HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard, Boston, Massachusetts, United States of America

Salim S. Abdool Karim

Affiliations CAPRISA – Centre for the AIDS Programme of Research in South Africa, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, United States of America

Thumbi Ndung'u

Affiliations HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard, Boston, Massachusetts, United States of America

Quarraisha Abdool Karim

Affiliations CAPRISA – Centre for the AIDS Programme of Research in South Africa, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, United States of America

William H. Carr

wcarr@mec.cuny.edu

Current address: Department of Biology, Medgar Evers College, The City University of New York, Brooklyn, New York, United States of America

Affiliations HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa, Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard, Boston, Massachusetts, United States of America

Competing Interests

The authors have read the journal's policy and have the following conflicts: Salim Abdool Karim and Quarraisha Abdool Karim were the co-Principal Investigators of the CAPRISA 004 trial of tenofovir gel. QAK is co-Principal Investigator of the HIV Prevention Trials Network, which is undertaking HPTN 052 trial of treatment for prevention. SSAK is an executive committee member of the Microbicide Trials Network, which is undertaking the VOICE trial of oral and topical PrEP. Salim and Quarraisha Abdool Karim are also co-inventors of two pending patents (61/354.050 and 61/357,892) of tenofovir gel against HSV-1 and HSV-2 with scientists from Gilead Sciences. Gilead Sciences did not fund this project, however the drug used in the clinical trial from which samples were used for this study belongs to Gilead Sciences. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: VN MA WHC. Performed the experiments: VN. Analyzed the data: VN MA QAK TN SSAK WHC. Contributed reagents/materials/analysis tools: VN MA QAK TN SSAK WHC. Wrote the paper: VN MA QAK TN SSAK WHC.