Table 3.

Effect of infection by wild-type Afa/Dr DAEC strains C1845 and IH11128 on apical distribution and enzyme activity of brush border-associated hydrolasesa

EnzymeCellsMean relative immunofluorescence intensity ± SEMMean enzyme sp act (mU/mg of protein) ± SD (% inhibition)
SIControls2.78 ± 0.32135 ± 10
C1845 infected0.40 ± 0.14* 35 ± 15** (74)
IH11128 infected0.55 ± 0.20* 50 ± 20** (63)
DPPIVControls1.80 ± 0.25172 ± 7
C1845 infected1.25 ± 0.15* 124 ± 6* (28)
IH11128 infected1.30 ± 0.10* 123 ± 12* (28)
  • a Apical SI and DPPIV distribution was observed by indirect immunolabeling as described in Materials and Methods. Relative immunofluorescence intensity is reported as the mean ± SEM (arbitrary units). SI and DPPIV enzyme activities were determined on the total membrane fraction from control and infected (3 h postinfection) cells as described in Materials and Methods. Results are means ± standard deviation for five independent experiments conducted with successive cell passages. Percent inhibition of enzyme activity in infected cells calculated relative to enzyme activity in control cells is shown in parentheses. Statistical analysis comparing infected with control cells was performed with a Student ttest. Significant difference: ∗, P < 0.05; ∗∗, P < 0.01.