Potency of a genetically detoxified mucosal adjuvant derived from the heat-labile enterotoxin of Escherichia coli (LTK63) is not adversely affected by the presence of preexisting immunity to the adjuvant

The objective of the current studies was to evaluate whether the potency of a genetically detoxified mucosal adjuvant, derived from heat- labile enter otoxin of Escherichia coli (LTK63), was adversely affected by preexisting i mmunity. Studies of mice and pigs have involved consecutive intranasal immu nization with LTK63 and 2 different vaccines (influenza virus hemagglutinin and a protein- polysaccharide conjugate of Neisseria meningitidis group C) . The antibody responses to the vaccines plus LTK63 in naive animals were c ompared with the responses achieved in animals that previously had been imm unized with the alternate vaccine plus LTK63. The data showed that the resp onses of both animal models to intranasal immunization were not adversely a ffected by the presence of preexisting immunity to the LTK63 adjuvant.