[1] UNIV CALIF SAN FRANCISCO, DEPT MICROBIOL & IMMUNOL, SAN FRANCISCO, CA 94143 USA
[2] UNIV CALIF SAN FRANCISCO, DEPT MED, SAN FRANCISCO, CA 94143 USA
[3] UNIV CALIF SAN FRANCISCO, GEORGE WILLIAM HOOPER FDN, SAN FRANCISCO, CA 94143 USA
[4] UNIV CALIF SAN FRANCISCO, HOWARD HUGHES MED INST, SAN FRANCISCO, CA 94143 USA