[1] Stanford Univ, Sch Med, Div Endocrinol Metab & Gerontol, Dept Med, Stanford, CA 94305 USA
[2] Stanford Univ, Sch Med, Div Cardiovasc Med, Dept Med, Stanford, CA 94305 USA
[3] Stanford Univ, Sch Med, Grad Program Immunol, Stanford, CA 94305 USA
[4] Univ Oxford, Sir William Dunn Sch Pathol, Oxford OX1 3RE, England
[5] St Jude Childrens Res Hosp, Dept Infect Dis, Memphis, TN 38105 USA