[1] St Georges Univ London, Div Clin Sci, Res Ctr Infect & Immun, London, England
[2] Univ London London Sch Hyg & Trop Med, Fac Infect & Trop Dis, Dept Clin Res, London WC1E 7HT, England
[3] Univ Cape Town, Desmond Tutu HIV Ctr, ZA-7700 Rondebosch, South Africa
[4] Univ Cape Town, Inst Infect Dis & Mol Med, ZA-7700 Rondebosch, South Africa
[5] Univ Cape Town, Dept Med, ZA-7700 Rondebosch, South Africa
[6] NIAID, Immunol Lab, Vaccine Res Ctr, NIH, Bethesda, MD 20892 USA
[7] Univ Massachusetts, Sch Med, Dept Med, Worcester, MA USA