Intestinal antibody response after oral immunization with a prototype cholera B subunit-colonization factor antigen enterotoxigenic Escherichia coli vaccine.

A prototype oral enterotoxigenic Escherichia coli (ETEC) vaccine containing formalin-inactivated whole bacteria expressing colonization factor antigens CFA/I and CFA/II and cholera B subunit (CTB) has been tested for safety and immunogenicity in 20 adult Swedish volunteers. When given in three doses with 2-week intervals the vaccine was found to be safe and to give rise to specific IgA antibody responses in intestinal lavage fluid in most of the volunteers (CFA/I 82%, CFA/II 82% and CTB 91%). The frequencies and magnitudes of these responses, which were already maximal after two doses, were comparable with those previously found in patients convalescing from severe ETEC diarrhoea. All the vaccinated volunteers also responded with antitoxin IgA as well as IgG antibodies in serum, whereas the serum antibody responses against the CFAs were weaker and mainly of the IgA isotype.