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MR. THACHER: Yes, I will try to be brief. I would like to go back 
to the question Dr. Sinsheimer raised — What do we know about E. coli K-12 
and its being a nonpathogen? — because I am concerned that taking a consen- 
sus on this question will prevent us from looking into the problem more 
carefully. Most of the data which has been accumulated to show that it 
cannot be turned into a pathogen by adding genes from other organisms have 
been done on newborn pigs. We heard of one experiment of Dr. Formal's 
group where you can do this, where this has been tried with human beings. 
The problem is that we don't know enough of the history of E. coli K-12, 
which was originally a human pathogen before its many years of passage in 
the laboratory, to know what factor it is that it actually does lack which 
prevents it from being able to live in the human gut. 
Susan Wright explained carefully why E. coli in general is a very good 
pathogen, so I disagree with what Dr. Ginsberg said earlier. Dr. Szybalski 
also commented that E. coli K-12 cannot survive in humans; however, there is 
experimental data of Anderson showing that it may well multiply in the human 
gut, and data on sheep by Smith in Australia which shows that if you starve 
them for two days, that the E. coli K-12 can survive for much longer times. 
So I would like to ask that this question not be closed, and be examined more 
carefully, because E. coli K-12 as HV1 in these new Guidelines will be used 
to clone almost the entire animal kingdom, save mammals and birds. 
I would like to raise one other point. In the analysis of HV2 strains, 
it is proposed that they be analyzed on the basis of data given by the inves- 
tigator who designs the strain. I think it would be worthwhile to have 
independent checks of that data on HV2 strains and their ability to fit 
within the Guidelines. 
Thank you. 
DR. FREDRICKSON: Thank you, Mr. Thacher. 
Dr. Davis, I had earlier said, wanted to make a short comment, and he 
would like to make it now. 
DR. DAVIS: Thank you. I would like to comment on an aspect of Dr. 
Schwartz's analysis that seems to me worth a moment because it permeates 
much of the apprehension that has been expressed. 
The model that he has chosen, the various physical models, seem to me 
not to be models for the biological situations at all. He is dealing with 
complex machinery, whether a reactor or a space object, in which any one of 
many things can go wrong, or a series of interacting things can go wrong and 
destroy its function. The model for this, the biological model, would be 
what Detrick was after originally, to try to make epidemics, and one of the 
reasons that Fort Detrick was abandoned was in fact that they did not succeed 
in making good epidemogenic organisms. Things could go wrong, and the fate of 
the organisms couldn't be predicted. 
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