1. Department of Immunology, University of Zimbabwe, Harare, Zimbabwe.
2. Department of Immunology, National Institute of Health Research, Harare, Zimbabwe.
3. Department of Paediatrics and Child Health, University of Zimbabwe, Harare, Zimbabwe.
4. Department of Molecular Biology, University of Oslo, Oslo, Norway.
5. Department of Community Medicine, University of Zimbabwe, Harare, Zimbabwe.
6. Department of Obstetrics and Gynaecology, University of Oslo and Rikshospitalet, Oslo, Norway.
7. Department of Microbiology, University of Oslo and Rikshospitalet, Oslo, Norway.