1. Department of Molecular Medicine and Haemotology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa.
2. Institute of Human Virology-Nigeria, Abuja, Nigeria.
3. University of Maryland, College Park, Maryland.
4. Makerere University, Kampala, Uganda.
5. Coriell Institute for Medical Research, Abuja, Nigeria.
6. National Institutes of Health, Bethesda, Maryland.
7. Clinical Laboratory Services, University of the Witwatersrand, Johannesburg, South Africa.