[1] Univ Penn, Dept Microbiol, Perelman Sch Med, 331 Biomed Res Bldg 2-3,421 Curie Blvd, Philadelphia, PA 19104 USA
[2] Univ Penn, Inst Immunol, Perelman Sch Med, 331 Biomed Res Bldg 2-3,421 Curie Blvd, Philadelphia, PA 19104 USA
[3] Philadelphia Corporal Michael J Crescenz VA Med C, Med Res, A424 Univ & Woodland Ave, Philadelphia, PA 19104 USA
[4] Univ Penn, Perelman Sch Med, Dept Med, Div Gastroenterol, 421 Curie Blvd, Philadelphia, PA 19104 USA