ABSTRACT
To understand the role of Campylobacter jejuni surface proteins in the interaction of C. jejuni with cultured mammalian cell lines in vitro, we developed a ligand-binding assay. This procedure allowed us to antigenically identify C. jejuni outer membrane proteins (OMPs) that attach to intact host cell membranes. OMPs isolated from an invasive strain and a less invasive strain were antigenically indistinguishable. However, we found that proteins with molecular masses of 28 and 32 kilodaltons (kDa) from just the invasive strain bound to HEp-2 cell monolayers. Binding of the 32-kDa OMP was cell line specific and correlated directly with the ability of the invasive C. jejuni strain to penetrate. Such a correlation was probably also true for the 28-kDa OMP. We also investigated the binding of glycine acid extracts with cell line HEp-2. We identified four proteins with apparent molecular masses of 28, 32, 36, and 42 kDa in the invasive strain extracts that bound to HEp-2 cells. In contrast, only the 36-kDa protein from the less invasive strain bound to HEp-2 cells. Our data suggest that binding of these surface exposed proteins may play a key role in C. jejuni-host cell interactions and ultimate invasion.
