[1] Johns Hopkins Univ, Sch Med, Div Infect Dis, Baltimore, MD 21205 USA
[2] NCI, Expt Immunol Lab, SAIC Frederick Inc, Frederick, MD 21701 USA
[3] NCI, Div Canc Epidemiol & Genet, Rockville, MD USA
[4] Univ Calif Los Angeles, Los Angeles, CA USA
[5] NHLBI, Div Blood Dis & Resources, Bethesda, MD 20892 USA
[6] Univ Calif San Francisco, San Francisco, CA 94143 USA