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.

Abstract: The present invention provides an expression system for producing a B subunit of a cholera toxin (CTB) wherein the expression system comprises a Vibrio cholerae host cell lacking the functionality of a thyA gene; and an expression vector comprising a functional thyA gene and a CTB gene which is substantially free of the flanking sequences immediately contiguous by the 5? and 3? end of the CTB gene in the naturally occurring genome of the host cell from which the CTB gene is derived. The present invention also provides a method of producing CTB, and an isolated nucleic acid construct that is used as an expression vector in the expression system.

Abstract: A method of producing a thy A?strain of vibrio cholerae comprising the step of site-directed mutagenesis in the V. cholerae chromosome at the locus of the thy A gene SEQ ID NO: 1 of FIG. 1, is described. Particularly, a ? thy A strain of Vibrio cholerae lacking the functionality of the thy A is disclosed. This strain may comprise one or several episomal autonomously replicating DNA elements, such as plasmids, having an optionally foreign, e.g. E. coli, functional thy A gene that enables the strain to grow in the absence of thymine in the growth medium, and optionally having a structural gene encoding a homologous or heterologous protein. Further, proteins encoded by a structural thy A gene and the 5?-flanking region are described as SEQ ID NO: 4 of FIG. 4 and SEQ ID NO: 5 of FIG. 5, respectively. Additionally, a vaccine comprising a Vibrio cholerae ? thy A strain of the invention or a thy A?strain of Vibrio cholerae produced by the method of the invention is disclosed.

Abstract: A polypeptide selected from peptides (1) and functional derivatives and pharmaceutically acceptable salts thereof; pharmaceutical compositions containing one or more of these polypeptides; and a method for inhibiting microbial growth in animals using such polypeptides.

Abstract: A method of cultivating bacteria having genes in plasmids which code for surface or membrane bound antigens or other proteins and which are expressed in a temperature regulated manner for the production of desired bacterial products, is disclosed. The bacteria are first cultivated in a culture medium to an inoculum under such temperature conditions that the bacteria retain their plasmids and no expression occurs, e.g. 20.degree. C., and then in a culture medium under such temperature conditions that expression occurs and before the bacteria lose their plasmids they are harvested, and the desired product is isolated.

Abstract: Novel polypeptides having lymphocyte stimulating factor activity are disclosed, as well as the use thereof for treating African sleeping sickness. Also, the corresponding nucleic acid sequences are provided as well as truncated forms which encode polypeptides exhibiting enhanced biological activity.