TABLE 2.
Effects of point mutations within Dr hemagglutinin on binding to CHO CD55+ cells and on CD55 and CD66e clustering in fully differentiated human intestinal Caco-2/TC7 cells.
| Plasmid | % of 14C-labeled bacteria bound ± SEMa
|
CD55 and CD66e clusteringb | |
|---|---|---|---|
| CHO CD55+ cells | TC7 cells | ||
| pCC90 | 6.60 ± 0.3 | 5.5 ± 0.4 | Positive |
| pCC90-D54stop | 0.40 ± 0.04∗ | 0.7 ± 0.2∗ | Negativec |
| BN17 (draE) | 0.25 ± 0.03∗ | 0.5 ± 0.2∗ | Negativec |
| pCC90-D54V | 5.70 ± 0.3 | 5.1 ± 0.5 | Positive |
| pCC90-D54Y | 6.60 ± 0.2 | 5.5 ± 0.2 | Positive |
| pCC90-T90M | 6.30 ± 0.3 | 5.8 ± 0.4 | Positive |
| pCC90-I113T | 6.30 ± 0.3 | 5.8 ± 0.5 | Positive |
| pCC90-D54G | 4.00 ± 0.2∗ | 2.0 ± 0.3∗ | Weakly positive |
| pCC90-D54C | 4.70 ± 0.3∗ | 3.6 ± 0.5∗ | Negative |
Statistical analysis between pCC90 versus mutants was performed with a Student t test. ∗, significant difference at P < 0.01.
CD55 and CD66e clustering around bacteria adhering onto fully differentiated human intestinal Caco-2/TC7 cells observed after indirect immunolabeling of CD55 and CD66e with anti-CD55 MAb IF7 and polyclonal rabbit anti-CEA antibody, respectively.
Although E. coli(pCC90-D54stop) and E. coli BN17 (draE) were not adherent to Caco-2/TC7 cells, isolated adhering E. coli could be observed in randomly distributed cells for which no CD55 and CD66e clustering was observed.