[1] Indiana Univ, Sch Med, Dept Microbiol & Immunol, Indianapolis, IN 46202 USA
[2] Walther Oncol Ctr, Indianapolis, IN 46202 USA
[3] Walther Canc Inst, Indianapolis, IN 46208 USA
[4] Vanderbilt Univ, Sch Med, Dept Microbiol & Immunol, Nashville, TN 37232 USA