57 
Slide 19 
Guidelines for Use of Polyoma and SV40 
as Vectors 
2 . 
'Foreign' DNA 
Physical Containment 
Polyoma 
SV40 
With Virion Production 
non-pathogen 
P3 
P4 
if purified, cloned, harmless 
P3 
P3 
low pathogenicity 
P4 
— 
No Virion Production 
non-pathogen 
P3 
P3 
low pathogenicity 
P3 
Still considering polyoma vectors, P3 conditions are required for ex- 
periments in which no virus particles are produced. When SV40 is the vec- 
tor, and virus particles are produced, P4 conditions must be used if the 
foreign DNA is from a non-pa thogenic organism, and experiments can be moved 
to P3 only after extensive and specified kinds of purification and demon- 
stration that no harmful genes are present. 
SV40 cannot be used at all for experiments with DNA from pathogenic 
organisms. When no SV40 virus particles are produced, experiments with 
recombinants derived from non-pathogenic agents can be carried out in P3 
conditions . 
The guidelines also contain recommendations for experiments in which 
plant cells would serve as hosts for recombinant DNA. These cells might be 
single plant cells grown under laboratory conditions, or seedlings or plant 
parts, or whole small plants. This is, in fact, the only instance where the 
guidelines address the question of recombinant DNA experiments with whole 
multicellular organisms. 
Vectors for use in experiments with plants include plant organelle DNA 
such as the DNA of chloroplasts and DNA of viruses of low pathogenicity. 
These vectors offer moderate levels of biological containment, and the 
guidelines suggest the physical containment outlined on the next and last 
slide (20). As before, this is organized according to the source of the 
foreign DNA. If the foreign DNA is derived from a species in which the 
vector DNA is known to be able to reproduce, P2 conditions are required. 
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