Adjuvant activity of a nontoxic mutant of Escherichia coli heat-labile enterotoxin on systemic and mucosal immune responses elicited against a heterologous antigen carried by a live Salmonella enterica serovar typhimurium vaccine strain

Systemic and mucosal antibody responses against both the major subunit of c olonization factor antigen I (CFA/I) of enterotoxigenic Escherichia coli (E TEC) and the somatic lipopolysaccharide expressed by recombinant bivalent S almonella vaccine strains were significantly enhanced by coadministration o f a detoxified derivative with preserved adjuvant effects of the ETEC heat- labile toxin, LT(R192G). The results further support the adjuvant effects o f LT(R192G) and represent a simple alternative to improve responses against passenger antigens expressed by orally delivered Salmonella vaccine strain s.