LamB-mediated adherence of enteropathogenic Escherichia coli to HEp-2 cells.

AIMS

To establish the role of maltoporin (LamB) in adherence of enteropathogenic Escherichia coli (EPEC) to epithelial cells in vitro.

METHODS AND RESULTS

Three strains, wild type (WT) EPEC, a maltoporin (LamB) mutant DeltalamB, and DH5alpha were used to study adherence to cultured HEp-2 cells. Mutant DeltalamB was found to be deficient in adherence compared to WT EPEC. Adherence of DeltalamB was restored to wild type levels when complemented with the cloned lamB gene. The non-adherent strain DH5alpha also adhered to HEp-2 cells when it harboured the cloned lamB gene. The LamB protein was isolated from WT EPEC by electroelution and antibodies were raised in rabbits. The specificity of the antibodies was analysed by Western blotting. Anti-LamB antiserum reduced adherence of WT EPEC to HEp-2 cells. The LamB protein was coated on latex beads and the beads adhered to HEp-2 cells. Anti-LamB antiserum prevented bead adherence to HEp-2 cells. Multiple sequence alignment showed that the L9 loop of EPEC LamB had four amino acids different from the L9 loop of LamB from several other related pathogens.

CONCLUSIONS

LamB serves as an alternative or additional adherence factor for EPEC.

SIGNIFICANCE AND IMPACT OF THE STUDY

Adherence is an important component of the pathogenesis of noninvasive pathogens like EPEC. A putative adhesin such as LamB, which has already been found to be co-expressed with virulence factor EspB may be a potential vaccine candidate for control of EPEC and related pathogens.