Inhibition of F4-fimbriated ETEC adherence to IPEC-1 cells by L. amylovorus
IPEC-1 cells have been shown to support the adherence of E. coli carrying F4-type fimbriae [38]. Next the L. amylovorus strains were tested in three different experimental set-ups (exclusion, displacement and competition as described in Methods) to evaluate if the observed differences in their adherence to IPEC-1 cells correlated with their abilities to inhibit ETEC adherence in the same model. The results were evaluated by comparing the adherence of ETEC in the presence or absence of the L. amylovorus strains. The strains DSM 16698, GRL 1112, GRL 1115 and GRL 1118 were able to inhibit pathogen adherence if they were added beforehand (exclusion, Figure 3A) or simultaneously with ETEC (competition, Figure 3B); the strain DSM 20531T achieved only a borderline inhibition when added beforehand (Figure 3A), and the rest of the strains had a negligible or even a slightly enhancing effect on ETEC binding in both assays (Figures 3A and B). Importantly, none of the strains was able to displace previously bound ETEC from IPEC-1 cells (displacement, Figure 3C).
Figure 3  Inhibition of F4-fimbriated ETEC adherence to IPEC-1 cells by L. amylovorus. The inhibition of F4-fimbriated ETEC adherence to IPEC-1 cells by the indicated L. amylovorus strains in exclusion (A), competition (B) and displacement assays (C) was tested with 3H-labeled ETEC cells as detailed in Methods. The means and standard deviations of 3–7 independent experiments are shown, each with three technical replicates.

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