[1] John Radcliffe Hosp, Nuffield Dept Med, Oxford, England
[2] Leiden Univ, Med Ctr, Dept Immunohaematol, Leiden, Netherlands
[3] Univ KwaZulu Natal, Dept Obstet & Gynaecol, Nelson R Mandela Med Sch, Durban, South Africa
[4] Univ KwaZulu Natal, Dept Paediat & Infant Hlth, Nelson R Mandela Med Sch, Durban, South Africa
[5] Massachusetts Gen Hosp, Partners AIDS Res Ctr, Boston, MA USA
[6] Massachusetts Gen Hosp, Ctr Infect Dis, Boston, MA USA
[7] Harvard Univ, Sch Med, Boston, MA USA
[8] Queen Elizabeth Hosp, Bridgetown, Barbados
[9] Univ Oxford, Dept Evolut Biol, Oxford, England
[10] Univ KwaZulu Natal, Ctr HIV & AIDS Networking, Durban, South Africa
[11] Univ Oxford, Peter Medawar Bldg Pathogen Res, Oxford OX1 9SY, England