[1] EMORY UNIV, YERKES REG PRIMATE RES CTR, ATLANTA, GA 30322 USA
[2] EMORY UNIV, DEPT PATHOL, ATLANTA, GA 30322 USA
[3] HARVARD UNIV, SCH PUBL HLTH, BOSTON, MA 02115 USA
[4] STANFORD UNIV, MED CTR, SCH MED, DEPT MICROBIOL & IMMUNOL, STANFORD, CA 94305 USA