1. Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
2. Botswana-Harvard School of Public Health AIDS Initiative Partnership for HIV Research and Education, Gaborone, Botswana.
3. Ministry of Health, Botswana Harvard HIV Reference Laboratory, Gaborone, Botswana.
4. Department of Immunology and Infectious Diseases, and the Harvard School of Public Health AIDS Initiative, Harvard School of Public Health, Boston, Massachusetts.