Characterized Clones 
The enclosed table is an addendunn to the previously published tables of 
characterized clones. Data on characterized clones were submitted by indi¬ 
vidual investigators to the Office of Recombinant DNA Activities (ORDA). 
These requests were individually reviewed by the NIH Recombinant DNA 
Advisory Committee. Committee actions to permit reduction of containment 
levels were based on evidence that clones are rigorously characterized 
(e.g., hybridization and restriction endonuclease fragmentation analysis 
nucleotide sequencing, R-loop analysis, and), free of harmful genes (e.g., 
sequences contained in indigenous tumor viruses or which code for toxic 
substances), the biological properties of the vector are maintained, and the 
cloned fragment is genetically stable. 
In accord with the 1978 G uidelines, requests to lower containment levels 
for characterized recombinant clones by one step in physical or biological 
containment should be submitted to the Institutional Biosafety Committee 
(IBC), which can approve such reductions. The reduction of containment 
levels for characterized clones derived from primate DNA require NIH 
review and approval as does the reduction for more than one step in con¬ 
tainment. These requests should be submitted to ORDA. 
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