87 
DR. FREDRICKSON: Any other questions or comments for Dr. Gottesman? 
Yes, Dr. Chilton. 
DR. CHILTON: Has testing been 
ing vehicles can escape either with 
test organisms or people? 
done to test whether the licensed don- 
or without antibiotic selections in the 
DR. GOTTESMAN: Testing, limited testing has been done. That is, mouse 
feeding experiments have been done with both the phage and plasmid systems, 
and the results are that very little is recovered. But I suspect in the 
plasmid system what has mostly been looked at is the host itself, Chi-1776. 
And in the phage there seems to be very little survival of the phage in 
passage through mice. 
DR. CHILTON: I am concerned more about the plasmid vectors, of course, 
where there is a direct selection out there in the environment to cause the 
spread . 
DR. GOTTESMAN: Certainly no testing that I know of has been done real- 
ly out into the environment, that is, letting it go free and seeing whether 
you find the drug resistance markers. I think probably the closest to that 
is the paper that Dr. Szybalski was just talking about, that is, monitoring 
over a long term in a lab that was using transmissible drug resistance 
plasmids . 
DR. CHILTON: That is not the licensed cloning vehicles. Is there any- 
thing being done with the licensed cloning vehicles? 
DR. GOTTESMAN: No, of that sort I don't think, in any extensive way. 
DR. CHILTON: Is there such testing planned? 
DR. GOTTESMAN: Yes, that is an essential part of the EK3 testing — that 
is, of the testing for anything to go on to the next level of containment. 
That would be first. 
DR. CHILTON: But we don't have the data for even the EK2? 
DR. GOTTESMAN: No. Well, I mean most of the EK3 candidates would be 
the best of the EK2s. 
the 
DR. CHILTON: Are you saying that we don't have data that tell us what 
rate of escape of the licensed EK2 vector is? 
DR. GOTTESMAN: Do we have 1776? Were any of those rat feeding experi- 
ments really looking at the plasmid after feeding? Do any of you people 
know? I have the impression they are all looking at 1776 survival itself. 
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