Identification of immunodominant regions within the C-terminal cell binding domain of intimin α and intimin β from enteropathogenic Escherichia coli

Enteropathogenic Escherichia coli (EPEC) strains are a common cause of infantile diarrhea in developing countries. EPEC strains induce a characteristic attaching and effacing (A/E) lesion on epithelial cells. A/E lesion formation requires intimin, an outer membrane adhesin protein. The cell-binding activity of intimin is localized at the C-terminal 280 amino acids of the polypeptide (Int280). So far, four distinct Int280 types (α, β, γ, and δ) have been identified. The aim of this study was to identify immunodominant regions within the Int280α and Int280β domains. Recombinant DNA was used to construct and express overlapping polypeptides spanning these domains. Rabbit anti-Int280 antisera and human colostral immunoglobulin A were reacted with these polypeptides in Western blots and enzyme-linked immunosorbent assays. The results obtained with the rabbit antisera showed the presence of two separate immunodominant regions which are common to both Int280α and Int280β. The first localized within the N-terminal region of Int280, and the second localized between amino acids 80 and 130. The results with the human colostra revealed one reactivity pattern against the Int280α fragments but two different reactivity patterns against the Int280β domain.