1. Botswana Harvard AIDS Institute Partnership, Gaborone, Botswana
2. Usher Institute, University of Edinburgh, Edinburgh, UK
3. Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, CA, USA
4. University of Southern California, Los Angeles, CA, USA
5. University of California, Los Angeles, CA, USA
6. MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, UK