June 17, 1954

Dr. 4ene J Dubos
Rockefeiler Institute
66th Street and York Ave.
New York al, N.Y.

Dear Dr. Dubos:

Thank you for your note. I was of course mistaken on immunity to
pullorum— at least all the texts on poultry disease indicate that such
immunity is not found even in birds that have recovered, much less after
vaccination. I was confused qs between a prophylactic vaccine ani the
diagnostic antigen. If this lack of immnity 1s in fact true, it should
be rather disquieting to the typhoid enterprise. I am not sure how well-
founied these textbook citations are-- perhaps more work is still in order.

I am still compelled to chuckle at ths wit of your introduction to

my paper at Rutgers, ani want to thank you for setting a light and infor—
mal tone to the proceedings, which might have been deadly sombre otherwise.

R Yours sincerely,

| Joshua Lederberg
/