[1] UNIV PENN, SCH DENT MED, CTR ORAL HLTH RES, PHILADELPHIA, PA 19104 USA
[2] UNIV PENN, SCH VET MED, DEPT PATHOBIOL, PHILADELPHIA, PA 19104 USA
[3] UNIV PENN, SCH MED, DEPT MED, PHILADELPHIA, PA 19104 USA
[4] NIAID, CLIN INVEST LAB, BETHESDA, MD 20892 USA