BACTERIAL VACCINE VECTORS AND BACILLUS-CALMETTE-GUERIN

Recent advances in biotechnology now allow a more modern approach to t he development of vaccines, particularly that of recombinant vaccines. Bacterial vaccine vectors have the advantage over viral vectors in th at the former have the ability to express a greater number of antigens in different forms. Although no recombinant bacterial vaccines are cu rrently in use, bacillus Calmette-Guerin (BCG), Salmonella species, an d Escherichia coli are being developed as vaccine vectors. We review p lasmid systems and mutant strains developed for the expression of fore ign antigens, with particular emphasis on those developed for BCG. We describe the development of antigen expression systems as well as the immune response elicited by recombinant BCG vaccine strains to bacteri al and human immunodeficiency virus (HIV) antigens. A modified recombi nant BCG carrier with selection for the stable maintenance of rDNA is proposed.