1. Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
2. Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA
3. Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA, USA
4. Zambia–Emory HIV Research Project, Lusaka, Zambia