ARMY MEDICAL SERVICE GRADUATE SCHOOL
WALTER REED ARMY MEDICAL CENTER
WASHINGTON 12, D.C.

IN REPLY REFER TO

 

September 21, 1953

Prof.e Je Lederberg
Department of Genetics
University of Wisconsin
College of Agricultupe
Madison, Wisconsin

Jear Joshua,

Let me first offer my congratulations on your recent achievements. I had hoped to
be at the SAB meetings but was unable to make it. I have just returned from leave
which may explain the smiky delay in answering your letter.

= have not seen Larry Weed lately, but have heard that his manusckipt was accepted
by the Je Bact. and should be published shortly. There may possibly be a oopy of
the manuscript on file here which could be sent youe I am not sure of Larry's
exact address other than Johns Hopkins, Baltimore. However, I can get his complete
addrees, if you don't already have ite

As far as the two E. coli cultures are concerned, neither have the XII factor. Culte
urally, the D-139 strain is interesting in that the cclonies take on a donut-shaped
appearance within about 48 hourse We noticed a similar colonial appearance in a
Shigella alkalescens culture which carried a phase. The cultures have not been
examined in detail, but there is a reference for the D~139 (Ven Oye= Ann. Instit,
Paste 81, pg 684 Dec. 1951).

With regard te the Vi phage transductions, our earliest experiments ,reported in the

ummx note,were confined to the xylose factor. However, if a cell suspension(Xyl= Arab-)
is treated with a lysate from a Xylf arab/ strain and plated on EMB xylose and EMB arab
inose, considerably more positives appear on the arabinose plates(linearly related to

the number of phage particles used)than occur on the xylose plates. As an explanation,
it would seem that xylose is extremely inhibitory tim to the cells and may affect the
expression of some of the cellse This may also explain the complete lack of spontaneous
mutants on xylose control plates.

We have completed some reconstruction experiments as you had suggested witn encouraging
results. Using fhe precipitin reaction with antibody excess, it has been possible

to concentrate 10° cells (Vi positive) in the presence of 10*4 cells of strain 0901.
The Vi cells can then be detected on azar plates using oblique lightinse Both strains
were marked and could be checked selectively as a control after each washing of the
wrecipitate.
ARMY MEDICAL SERVICE GRADUATE SCHOOL
WALTER REED ARMY MEDICAL CENTER
WASHINGTON 12, D.C.

 

our present difficulty lies in developing a phage which will act from Vi to non-Vi
formse We have a strain of H901 which is carrying a Vi phage giving plaques on

Se typhi phage type A- Our vi positive variant which was isolated from this strain

of H901 by mouse passage was found to be untypable by the adaptet phage. Thir wee
confirned by Pe Re Edwards who indicated that the failure cf thie culture te resct.

with the group I] phages may be due to the fact that it is carrying a Vi phage active
ageirst strain Ae We have received a number of cultures from Edwards which were isolated
in the W form and which are carrying Vi phages. In our experierce, these cultures
appear to be mixed V and W forms and do not seem to offer a clear cut model for
transduction of the Vi antigen. Possibly our E901 eulture from which we have isolsted
the one Vi positive variant offers the same difficultye We would very much appreciate
any suggestions along these lires which you may havee

As a sideline, we have started examining some Shigella cultures, but have encountered
some difficulties particularly with phage F2(B) in our preliminary experiments.

recall your mentioning something about the whereabouts of John Jacquez (Stuyvesant).
received a card from a John Ae Jacquez, Ist Lte, M.Co, Army Medical Research Lab.,
Fert Erox, Kentucky and suspect that this may be the person in question.

tbe

xy

oe rely yours,

Lou Baron

Fele I recret to say that the pictures I took mkt suffered from faulty synchronization
of my flesh attachment. As a poor substitute I am enclosing a few pictures takensat
the CSE meetirgse