1. Human Biology Division, Fred Hutchinson Cancer Center , Seattle, Washington , USA
2. Molecular and Cellular Biology Program, University of Washington , Seattle, Washington , USA
3. Medical Scientist Training Program, University of Washington , Seattle, Washington , USA
4. Public Health Sciences Division, Fred Hutchinson Cancer Center , Seattle, Washington , USA
5. Centre for Public Health Research, Kenya Medical Research Institute , Nairobi , Kenya
6. Department of Global Health, University of Washington , Seattle, Washington , USA
7. Department of Epidemiology, University of Washington , Seattle, Washington , USA
8. Department of Medicine, University of Washington , Seattle, Washington , USA
9. HIV Section, United Nations Children's Fund , New York, New York , USA
10. Department of Paediatrics and Child Health, University of Nairobi, Kenyatta National Hospital , Nairobi , Kenya
11. Department of Pediatrics, University of Washington , Seattle, Washington , USA
12. Howard Hughes Medical Institute , Seattle, Washington , USA