January 13, 1956

Dr. Joan Taylor

Salmonella Reference Laboratory
Central Public Health Laboratory
Colindale Aveme

London NW 12, England.

Dear Dr. Taylor:

During the last few years, we've run into two occurrences of what
appears to be a genetic duplication of a first—phase H antigen, Qne is
Edwards' S. paratyphi B java N25, which turne out to be H,” H,~?* (and

thus has a second anomaly, a 1,2 antigen which is homologous with other
phase-l(a); the second came up in a transduction experiment of S. typhimurium
-~x S. abony, and came out b,i:enx. We have gone fairly far towards com-
pleting the genetic analysis of these stocks, and it appears that there

has been a duplication of the Hy gene so that two phase-l determinants

can persist in the same cell. Such duplications have been attributed with

but these are probably the firstydemonstrations in bacteria.
aa
I wrote about this to Phil Edwards; in replying, he mentioned his
own experience with d,eh: forms, and also a culture he had recé&ved from
you as Col 529-55, 4,12: r,i - lw. As he mentioned that the Jatter had

not been published, I thought I should consult with you before working on

it. We have in mind to try to correlate this isolate as a presumed natural
occurrence of a duplication similar to the other two, mentioned above. Does
this overlap any of your plans, or those of your associates? Phil gave m .
no other details: if you can tell me anything of the source of this culture,
and particular its serological and variational behavior, it would be very
helfful.

Please give our very best regards to Clive Spicer— would you tell him
"Thanks for the Brighton Rock"-— he'll know what I mean.

Your's sincerely, ;
4 j fo# /
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Sdshua Lederberg (’