US Patent 7595186 Cytotoxin-based biological containment

Method of conditionally controlling the survivability of a recombinant cell population and of containing such cells to an environment or containing replicons to a host cell is based on the use of proteic killer systems including E. coli relBE locus and similar systems found in Gram-negative and Gram-positive bacteria and Archae. Such systems are generally based on a cytotoxin polypeptide and an antitoxin or antidote polypeptide that in contrast to the cytotoxin is degradable by proteases. The recombinant cells are useful as vaccines, pollutant degrading organisms or as biological pest control organism e.g. expressing B. thuringiensis crystalline proteins.