JAN 2° 1973

MARTIN FROBISHER
APT, 393, ALEXANDER HAMILTON BLDG.
DRUMMERS LANE, WAYNE, PA. 19087

January 23, 1973

Dr. Joshua Lederberg,

Stanford University School of Medicine,
Stanford,

California 94305

Dear Joshua,

After our first work on "transmissable toxicenicity"we made
other experiments which, as I recall, were mainly attempts to
transmit toxigenicity to other species of bacteria. These led to
nothing and we turned our attention to other, unrelated, studies.

In 1929 I left Johns Hopkins to join the Rockefeller Founda-
tion group in studies of yellow fever. So far as I know, no one
followed up our streptococcus work, at least to the extent of
publishing pro or con. But my interest in the literature at that
time had turned exclusively to yellow fever so that papers on
searlet fever or streptococci would have escaped my attention.

I infer from your letter that you might be interested in any
missed leads or "pstponed opportunities” ani, at the risk of
wasting your time I cite one from our yellow fever studies. Among
the mosquitoes that harbor yellow fever virus for relatively long
periods but, so far as is knowl, never transmit by their bite, is
Mansonia titillans.

The late Dr. Nelson Davis, then Director of the yellow fever
laboratory in Bahia, Brasil, marveled over this. I suggested
that perhaps the saliva of the insect was visrucidally deta& Davis,
who was very expert at dissecting out mosquito salivary glands,
and I, spent a Sunday in the laboratory, he taking out dozens of
salivary glands from M. titillans and I immediately macerating
them in distilled water in la Motte “Little cups", -testing the
pH with dyes like brom-cresol purple. The glands appeared quite
acid. I believe yellow fever virus and other Group B Arboviruses
have since been shown to be acid-labile. We had no better means
of determining pH in those days in Bahia and no opportunity to
conduct further tests, including controls on Aedes aegypti. We
felt that our data were entirely, Phited and preliminary to just-
ify any conclusions. Perhaps similar physiological peculiarities
could account for other entomological specificities in arthropod
transmission of other pathogens.

With all vzood wishes and, as the Brasileifroes say,
Saudac6es collegiaes,

Gut

Martin Frobisher