9th September, 1974
Dear Professor Berg,
Thank you for your letter of the 2nd September.
I too was very glad to meet you, I do not know what "worst" you had expected, but so far as I was concerned I never intended to indulge in anything other than a mutually informative debate, carried out with good humour. In that respect I think we were successful. I don't know what form the eventual programme will take, because there will naturally be massive editing. However, it will be shown here on Monday, 16th September. Will you have an opportunity of seeing it yourself? Does this programme reach the States?
My only misgivings about participating in events of this sort are based on one's inability adequately to communicate the message to the audience, and eventually to the public. There is also no doubt that being under the glare of the lights induces some uneasiness in the participants. Lastly, we have no control over the editing, which may materially affect the final message.
I am glad to accept the invitation you extended to me after the meeting to attend the international conference in this field on the 27th February, 1975. There is a clear need for informed international debate and I agree that it must be a self generated critical analysis of where we are going, what seems in principle safe or unsafe, and what precautions, genetic and technical, should be observed in carrying our in vitro plasmid hybridisation.
The section you actually quoted to me from my Annual Review chapter was in the first paragraph on page 172 starting, as we recall, "These organisms frequently carry R factors, and even if they do not survive in the human intestine. . .I was of course referring, as I remarked at the meeting, to fresh animal E. coli of a much higher viability than K12 in competition with other E. coli in the human intestine.   So far as the last section is concerned, in which I quoted the paper by Formal et al. on the restoration of virulence to avirulent Sh.flexneri,  I assumed that a metabolic deficiency had rendered the shigella avirulent and that this deficiency was repaired by transfer from K12Hfr.
Naturally, the complex of characters that could determine virulence was already present in the shigella. I believe that the Hfr strain restored a run-of-the-mill character which was not directly connected with the virulence-determining complex, but which put the shigella metabolically back on its feet.
I look forward to meeting you again in February.
With kind regards,
Yours sincerely,
E.S. Anderson