With eukaryotes, attempts to clone segments of DNA using recombinant DNA technology from warm-blooded vertebrates genomes were to be performed only with vector-host systems that had demonstrably restricted growth capabilities outside the laboratory and in a moderate risk containment facility.
For eukaryotic organisms, cloning DNA fragments via recombinant DNA techniques from the genomes of warm-blooded vertebrates was feasible only when using vector-host systems that exhibited restricted growth both within and outside the lab, and in facilities with minimal risk control measures.