[1] UNIV PENN,MED CTR,DEPT MICROBIOL,209 JOHNSON PAVIL,PHILADELPHIA,PA 19104
[2] UNIV PENN,MED CTR,DEPT NEUROL,PHILADELPHIA,PA 19104
[3] UNIV PENN,MED CTR,DEPT NEUROPATHOL,PHILADELPHIA,PA 19104
[4] UNIV PENN,MED CTR,DEPT MED,PHILADELPHIA,PA 19104
[5] WISTAR INST ANAT & BIOL,PHILADELPHIA,PA 19104