15 . 
B. Experiments with Eukaryotic host-vectors. 
( a ) AN I MAL HOS T- VECTORS- 
Only cells which have been extensively studied as tissue culture 
lines should be used as hosts. P3 containment levels are recommended 
with these hosts for work using mitochondrial DNA and that from low- 
risk viruses. Experiments with DMA from viruses which are detrimental 
to economically important animals and plants should be upgraded to the 
P4 level. Transference of the experimental system to the whole animal 
should be justified before a peer review committee. Experimental set-ups 
using highly virulent or oncogenic viruses should be deferred until our 
experience substantiates their usefulness over the risk involved. 
The use of well characterised, modified viral genetic material as 
a highly contained vector for cloning in eukaryotic cells should be 
restricted to P4 containment facilities. We feel our caution is 
warranted because of the unknown hazards. A pathogenic, but low-risk 
virus lias the potentiality to acquire greater virulence in a foreign 
environment with abnormal controls and targets on release. Logically, 
experiments with oncogenic viral DNA should be halted because of the 
greater risks involved, and the epidemiological difficulties of tracing 
causation of increases in incidences of specific cancers. 
( b ) PLANT H OST-VE CTORS. 
A word about the containment levels. P2 containment as described is 
minimal and appears a token, gesture to standard microbiological technique. 
Because of the very nature of this type of work, up to now the techniques 
are much cruder than those used in microbiology. Therefore, we strongly 
recommend that cloning experiments in tissue culture be carried out at 
least at the P2 microbiological containment level when the plant is known 
not to harbour a pathogen. All other experiments with pathogen-containing 
tissue, deteached plant parts and whole plants should be up graded to 
the P3 containment status. 
In plants the modes of dispersal of pathogens do not necessarily 
depend on cell to cell contact either within the same plant or with other 
plants. Insects act as very efficient vectors of pathogenic agents, while 
spore-producing pathogens depend on either animals or air for their 
transmission. Thus, we feel that the most stringent conditions must 
prevail until further research and expertise with plants and plant tissue 
culture guarrantees that accidental "spills" can be eliminated or proven 
non-hazardous . 
Since it is still entirely unknown whether there will be rewards of 
so called "shotgun" experiments with whole plants, detached parts and 
cell culture, it is our opinion that such experiments should be halted at 
this time. Work with DNA which has been purified os rigorously as possibl 
(see above) and then introduced into plant cells in culture would be a 
more easily controllable system in which to test whether such experiments 
are worthwhile. 
( c ) RJNGAL^ or_SJMI LAR_L0WER EUKARY OTIC IIOST-VEf TflR S 
We strongly disagree with the sentiments of the first sentence of 
this section in the Woods Hole Guidelines - "The containment criteria 
for experiments on recombinant DNAs using these host vectors most closely 
resemble those tor prokaryotes, rather than the proceeding eukaryotes, in 
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