VECTOR DEVELOPMENT FOR THE EXPRESSION OF FOREIGN PROTEINS IN THE VACCINE STRAIN BRUCELLA-ABORTUS S19

A vector for the expression of foreign antigens in the vaccine strain Brucella abortus S19 was developed by using a DNA fragment containing the regulatory sequences and the signal peptide of the Brucella bcsp31 gene. This fragment was cloned in broad-host-range plasmid pBBR4MCS, resulting in plasmid pBEV. As a reporter protein, a repetitive antigen of Trypanosoma cruzi was used, The recombinant fusion protein is stab ly expressed and secreted into the Brucella periplasmic space, inducin g a good antibody response against the T. cruzi antigen. The expressio n of the repetitive antigen in Brucella neither altered its growth pat tern nor generated a toxic or lethal effect during experimental infect ion, The application of this strategy for the generation of live recom binant vaccines and the tagging of B. abortus S19 vaccine is discussed . This is the first time that a recombinant protein has been expressed in the periplasm of brucellae.