FIG 1 .

MUC1 is a cell receptor for EAEC. (A) HEK293 cells transfected with pcDNA3 or pcDNA3-MUC1 were infected in suspension with EAEC strain 042 or with its isogenic fimbrial mutant (042aafA), each expressing a GFP reporter and analyzed by fluorescence microscopy (FM). Cell membranes were stained with FM4-64FX, and DNA was stained with DAPI. (B) Uninfected and EAEC 042-infected HEK293pMUC1 cells were stained with FITC-conjugated anti-MUC1 MAb and DAPI and analyzed by FM. Bacteria were stained with M4-FX64. (C) HEK293-pcDNA-MUC1 cells were infected in suspension as described above in panel A, and bacteria that adhered to cells were enumerated microscopically. (D) HEK293-pcDNA3-MUC1 cells were treated with two concentrations (20 U and 40 U) of neuraminidase (Neu) for 1 h before infection with strain 042 followed by quantification of bacterial adherence as described above for panel C. (E) HEK293 cells not expressing or expressing recombinant MUC1 were infected with EAEC strain 17-2 (which expresses AAF/I), 55989 (AAF/III), or C1010-00 (AAF/VI), followed by quantification of bacterial adherence as described above for panel C. Bars represent the means of at least three independent experiments, with the error bars indicating standard deviations (SD) (error bars). Values that are significantly different (P < 0.05) are indicated by a bar and asterisk.