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: Hybrid molecules between heat-labile enterotoxin B subunit (LTB) and cholera toxin B subunit (CTB) are disclosed. Such a hybrid molecule comprises an amino-acid sequence which is composed of the amino-acid sequence of mature CTB in which such amino-acid residues are substituted with the corresponding amino-acid residues of mature LTB which impart LTB-specific epitope characteristics to said immunogenic mature CTB, or vice versa. In addition, a structural gene coding for such a hybrid molecule, a plasmid containing such a structural gene, and an immunogenic protein comprising such a hybrid molecule and optionally an immunoreactive amino-acid sequence of a prokaryotic or eukaryotic cell or a virus, are disclosed. Disclosed is also a vaccine, e.g. against enterotoxin-induced illness, comprising such an immunogenic protein, and a method of preventing or treating enterotoxin-induced illness in an individual.

Abstract: The present invention relates to somatotropin analogues with amino acid changes in the alpha-helix 1 regions of said somatotropins, alone or in combination with mutations in the alpha-helix 3 and/or alpha-helix 2 regions, plus combinations with other changes to the native amino acid sequence of somatotropins. The resulting analogues are stable for formulation in sustained release formulations, while maintaining biological activity. Further, methods for conducting site-directed mutagenesis on DNA encoding proteins and/or polypeptide also are provided.