Antibody response of children with enteropathogenic Escherichia coli infection to the bundle-forming pilus and locus of enterocyte effacement-encodedvirulence determinants

Enteropathogenic Escherichia coli (EPEC) express a plasmid-encoded type IV pilus termed bundle-forming pilus, which is associated with the formation o f bacterial microcolonies on cultured epithelial cells. Bacterial attachmen t and effacement of the enterocyte brush border membrane is attributed to a surface outer membrane protein adhesin termed intimin and EPEC-secreted pr oteins EspA, EspB, and EspD, Except for intimin, production in vivo or anti body response against these virulence determinants during natural EPEC infe ctions in young children has not been demonstrated. Antibody responses agai nst BfpA, intimin, EspA, and EspB were investigated in Brazilian children n aturally infected with EPEC, Generally IgG antibodies against BfpA and EspB were the most commonly found, followed by anti-EspA and intimin antibodies . Thus, bundle-forming pilus and locus of enterocyte attachment-encoded pro ducts are produced in vivo during natural EPEC infections and elicit an imm une response against heterologous EPEC virulence determinants. These findin gs have important implications in the immunoprophylaxis against EPEC infect ions.