COFrY

Central Enteric Reference Lab:ratory & Bureau

tat March, 1953.

Dear Doctor Crézé,

i must apologize for not having written before in res:onse to your letter
of the &th March. I have been away fron the laboratory and this explains the
de lay.

If the observations described in your letter are regularly reproducible
they eertainly merit to be followed up very carefully. I assume you are not
aware of the earlier work on antigenic variation of Salm. typhi and « specially
of the antecedents of strain H90*. 1 would like to drsw your attention to the
fact that spontaneous reversion of the Vieneg:tive variant strain H%1 to the
Vi-positive form has been observed before.

The history of the strain was given not long ago in the paper in the
Journal of Hygiene, 1951, 49, on pages 94-95 and more recently the details
were presented in Table 3 of ay Discussion Remarks, Oxford Syuposiun, 1952
[in the Press]. I am sending you under separate cover reprints of these papers,
together with those of other papers that may be of interest to you. Kindly
return after perusal the 1951 paper that is specially marked, as there are no
copics left of this vaper.

You will notice from Table 3 in the Discusagion “ emarkxs and from page 94
in the 1951 paper that the reverted [rejuvenated] Vi-positive form which Kauffmann
(1338 obtained in his souse experiments with strain HY01, was found by Craigie

1938) to belong to Viephage Tyce B1, the sane type to which the well-known strain

Ty2 belongs, which was isolated during the same outbreak in 1918. I have inter-
preted this finding aa one of the most striking inatanoes of stability of Vi-
phage type, vhich is one of the hereditary traits of the typhoid bacillus.

You wrote in your letter that Nicolle typed your induced mutant strain
as belonging to Vi~phage Type A. It is true that Type A may be derived, as a
variant, from each of the specific Vi-phage types by the process called “degrada~
tion®. You will find this described in many of the papers 1 am sending you,
starting from the paper by Craigie and myself (1947). i have marked the relevant
pages in some us the reprints. Nevertheless i‘ would be advisable to try to
obtain, by the technique you are employing , induced mutants of the strain H901
giving the bacteriophage reactions of Vi-phage Type 1.

ZI shall send you immediately after the taster holiday Lemco-steab cultures
of the two strains H901 and 0901 and i should be interested to hear whether

/these
-= Qa

these cultures can be induced to revert to the Vi-positive variant by the
procedure you have adopted. Although these Lemco-stab cultures have been
prepared only recently they will on plating certainly show a proportion of
“rough variants, «t any rete it should not be difficult to obtain typical
rough varients starti:g from these cultures.

If ycu again obtein variants which you consider to be induced Vi-positive
reversions, I shall be glad to examine a number of such cultures for their
antigenic composition and Viephage type. In this cese I would sugrest that
you select not less than hslf a dozen culture:, each derived from a single
colony. at the same time you could perhaps send also subcultures of the strains
menti-ned in your letter, that is to say the 5 and # cultures of H901 “rom which
you started and sone of the Vi-positive mutant cultures which had been examined
by lr. Nicolle, Your paratyphoid-B strain Ranson might also be added. The
best way of posting the cultures is either in Lemco agar stabs cr on amall
Corset ager slants.

ZI hope I have answered your queries to your satisfaction.
Yours sincerely,

(signed) a. Felix

krofessor J. Crésé,

Académie de Rennes,

Ecole de Flein sxercice Médecine et de tharmacie
d’ Angers, France.

Peds rrofessor Lederberg uwsy have nentioned to you the paper by H.L.Booy
and HoL.Wolff on “Un toe inducticn of Vi antigen formation in a strain of
Salmonella typhi free of Vi antigen”, :ublished in *Antonie ven Leeuwenhoek",
18, 183, 1952. 1 would like to draw your attention to the fact that this
paper calis for severe critician. 1t is evident from the two tables contained
in the paper that the authors are not familiar with the method of antigenic
analysis. The agglutination tests were carried out by slide agglutination,

a technique which has many pitfalla. There were no controls to show the
relative sensitivity of the suspensions to 0 or Vi agglutinins, or to
solutions of NaCl, or to normal proteins. Anyone acquaint:d with the past
history of strein H9C1 will refuse to accept the experiments by Booy and ‘olff
as evidence of genetic transduction of Vi antigen.

(signed) A..F.