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cell DNA and come out with it, and you get packaged viral particles, part 
host, part virus. That is a recombinant DNA experiment, but it goes on 
naturally all the time. It is the one that the Chairman referred to. 
You cannot convince people, I don't think, to do under P3 containment 
a cloning of a mouse gene in polyoma in a mouse cell. It is simply not rea- 
sonable to ask that. 
The EMBO has asked, within Europe we will try to set up a working party 
to consider the question of viruses, and we would be very pleased if we 
could make it a European/American venture. That is a separate issue, but 
clearly we would not be prepared to go along with these guidelines in our 
countries, because we do not believe we could honestly stand up to the 
people who are supposed to follow them and say that this is a reasonable 
set of proposals. 
I think finally I would like to mention very briefly what Helinski 
talked about this afternoon before the dinner break. In our opinion as 
long as you are using E. coli systems, and we are convinced of the data 
that says that E. coli K-12 and its derivative systems are absolutely 
adequately safe for the majority of experiments that are being contemplated, 
and we would say that if you are not using the DNA of a pathogen or DNA 
from a pathological tissue, then the basic ground rules for containment 
should be--and we make no distinction between primates and other mammals, 
nor between embryonic DNA and adult DNA, because we don't believe they are 
valid — for all birds and mammals, P2+EK2, and for all other eukaryotes 
P2+EK1 or P1+EK2, and for prokaryotes P1+EK1 . Those will be the basic 
ground rules. Now, you can elaborate exceptions which we would cheerfully 
agree to, like if you are using a pathogenic DNA and that is what you are 
going to clone. But we believe those are adequate precautions, given the 
risk. 
I do agree, however, with those who have spoken and said that when you 
are talking about novel host-vector systems, you should proceed with more 
caution, because it is the case that the one bacterial system that we know 
something about is E. coli , E. coli K-12, and the others are much less well 
developed. So I would agree entirely, and it seems to me that the justifi- 
cation for lowering the requirement for physical containment is that you 
are using an E. coli K-12 system which presents no hazard, and as long as 
you stop in that system, there doesn't seem to be much requirement for a 
very high level of physical containment unless you are specifically going 
out for the DNA of a pathogen, or the DNA from a pathological tissue. 
Thank you. 
DR. FREDRICKSON: Dr. Tooze, could I ask for you to clarify several 
things, and then I know there will be comments here. I didn't quite under- 
stand you. The EMBO Standing Committee advises that for shotgun experiments 
involving normal healthy tissue from nonpathogenic prokaryotes in an EK-12 
host-vector system you would use P1+EK1? 
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