The long-term cytoskeletal rearrangement induced by rabbit enteropathogenic Escherichia coli is Esp dependent but intimin independent

Attaching and effacing rabbit enteropathogenic Escherichia coli (REPEC) of the O103 serogroup adhere diffusely on HeLa cells and trigger a slow progre ssive cytopathic effect (CPE) characterized by the recruitment of vinculin and the assembly of actin stress fibres, In contrast to REPEC O103, the ref erence human EPEC strain E2348/69 is unable to trigger the CPE, In this stu dy, we have shown first that the fimbrial adhesin AF/R2, which mediates the diffuse adhesion of REPEC O103, was not sufficient to induce the CPE capab ility upon E2348/69. Non-polar mutants of REPEC O103 for espA, espB, espD a nd eae were then constructed. The four mutants were unable to induce attach ing and effacing lesions in the rabbit ileal loop model. The esp mutants we re no longer able to induce the CPE, whereas the eae mutant still induced t he CPE. Each espA, -B, -D mutant could be fully complemented in trans by th e corresponding cloned esp genes from both the parental strain and the CPE- negative E2348/ 69 strain, indicating that no single esp encodes the inform ation needed to confer the CPE phenotype, In conclusion, the CPE is the fir st example of an Esp-dependent but Eae (intimin)-independent alteration of the host cell cytoskeleton by certain EPEC strains.