Abstract: A mycobacteria transformed with an antigen-encoding gene, such as nef, under the control of a Streptomyces stress-responsive promoter, such as the S. albus groES/groEL1 promoter, and preferably associated with a synthetic ribosome binding site. The recombinant mycobacteria can be used as a vaccine against, for example, a pathogen which carries the antigen.

Abstract: The invention relates to a nucleotide sequence which is present at a position adjacent to the 5' end of the reverse sequence complementary to the open reading frame coding for a potential transposase contained in the insertion element IS900 in Mycobacterium paratuberculosis. The nucleotide sequence has promoter functions and contains important signals for the regulation of transcription and translation. The invention also relates to methods for cloning and expressing heterologous proteins using such regulatory sequences, to vectors and transformed host cells containing these sequences, and to immunogenic compositions prepared by expression of nucleotide sequences placed under control of these regulatory sequences.