December 14, 1952

Dr. P. BR. Fdwards
Comminigable Diseases Center
Box 185, Chamblee, Ga.

Dear Dr. Edwards:

Thank you for the confirmed diagnoses, and cultures #6 and N25 which
have arrived in good order.

I am afraid I must now make additional requests. I have reached about
a halfway point in genetic studies of phase variation. In the system
typhimurium -x abony, the product depends quite definitely on the phase
xu which the typhimurium displayed when the FA was made from it. TyM 1 gives
i:enx, almost exclusively, while Pi 1,2 gives almost all b:1,2. The next
question is the role of the recipient phase in determinkng this output.
8. abony (#103) is unsatisfactory for this purpose, as it has quite a high
rate of phase variation. For this experiment, phase stability is very
important, but I do not wish to yse monophasic straina at this point to
study the mechanism of diphasic variation. As I wish to continue with
typhimurium as the source of FA, for various reasons, sete good technical
reasons point to stocks such as abony, which have a,b,... in the first phase,
and and enx or nz) 6 for the secolid. Finally, not every Salmonella culture
will respond to the phages we now ‘have.

The existing serotypes which may £111 the bill are abony, imonctaninogy
bispebjerg, abortua—bovis, and durban. S. brandenburg, dar es salaam, gpeétingen
or javiana might also work, but I would need some 1 serum alom@ with the
cultures. I do not know how many isolates of these you are likely to have
in addition to those in the 1942 list. It would save me considerable effort
if it were possible to weed out those already known to be more than ordinarily
phase-variable. The kind of culture I need resembles; 5S, typhimurium LT-2
in giving the alternative phase very readily with serum selection, but in
being substantially pure by single colony tests. I should be grateful for
any number of isolates of these types, and whatever information on thetr
phase stability you may have. I already have your listed abony, 103, of
gourse , but notbthe others mentioned.

Spicer is now getting on with his stddies on somatic antigen transductions.
So far there have not been any definite results (except that huge quantities
of serum are consumed), but in anticipation of success I wondervif I might
ask for S. bredeney and 3. schlé&ssheim, and a few ml. of V and XXVII serums.
At this point, may I ask whether it would be all right for Spicer to join
us for a few days during our forthcoming visit (Feb.1 6 10 days). He will
be en route back to England (the Central Public Bealth Lab, at Colindale),
but would like tery much to sppnd a short time visiting your lab. while we
are there.

Sincerely,

Joshua Lederberg