Abstract: A recombinant operon comprising a gene assembly wherein there are at least two structural genes coding for at least two major subunits of colonization factor antigens (CFs) associated with enterotoxigenic Escherichia coli bacteria (ETEC), is disclosed. Further disclosed is a host cell, such as an Escherichia coli cell, genetically engineered to comprise such a recombinant operon, wherein said operon is located on an episomal element, such as a plasmid, or integrated in the chromosome of said host cell. Also disclosed is a method of producing a host cell capable of expressing from said operon at least two major subunits of colonization factor antigens (CFs) associated with enterotoxigenic Escherichia coli bacteria (ETEC). In addition, a vaccine composition against diarrhea comprising at least one such host cell together with pharmaceutically acceptable excipients, buffers, and/or diluents is disclosed. Finally is disclosed the use of said operon in the production of such a vaccine.

Abstract: Escherichia coli strains, such as enterotoxigenic E. coli strains, genetically engineered to express from recombinant plasmids one or more colonization factors (CFs) associated with enterotoxigenic Escherichia coli bacteria (ETEC) in an increased amount compared to said CFs expressed by ETEC wild-type reference strains, as well as a method of producing such strains, and vaccine compositions against diarrhea comprising such strains, are described. Further, E. coli strains expressing unnatural combination of at least two different CFs, e.g., CFA/I+CS2, CFA/I+CS6, or CS2+CS4 are disclosed.