LIVE POLIO IRUS VACCINES

DISCUSSION
CHAIRMAN ANDERSON: These papers are now
open for discussion.
line of defense against the infection invasion
from that route.
DR. ARMSTRONG: The virus of which I speak
is not a poliovirus, but is a neurotropic virus.
The mouse is its natural host, and these observations,
I think, may have some bearing on some
of the unknown factors which play a part in
susceptibility following feeding.
I had an isolate of lymphocytic choriomeningitis
from 1933. It had been carried through
about 200 mouse-brain-to-mouse-brain passages,
and had been stored in the deep freezer. So I
took that out and thought I would try feeding it.
as we have had so little experience with vaccines
administered by feeding.
I found that this virus, when fed to mice, or
given by stomach tube, failed to give any symptoms
whatever. But when I tried it intracerebrally
it was lethal in about three hundredths
of a cc. of one to a million dilution. When fed,
it produced high immunity. Here, then, was a
virus which was harmless when fed, but which
was lethal in one to one million of a cc. dose
when given intracerebrally.
Now, I think it would mean more to me if
these viruses which were tested and found to
change their virulent markers, had been found
outside the intestinal tract-if it is more virulent,
it should invade the intestinal tract. But
these viruses were isolated from the intestinal
tract. One cannot be sure it was the same virus.
I think that search should be made for these
viruses of changed character, not in the intestine,
but after invasion from the intestine.
What enables it to penetrate the intestine may
be an entirely different thing than what enables
it to affect the brain.
Now, when we give a virus into the brain, we
do several things. We break the meninges, injure
nerve tissue, rupture capillaries and blood
vessels, and put the virus on high concentration,
under pressure, in contact with injured cells
which have had no experience at all in dealing
with infection by this route.
In the intestinal tract, however, we are dealing
with a tissue that has been for ages the first
39
DR. SABIN: I would like to ask Dr. Armstrong
to tell us whether or not the LCM virus he fed
to mice showed any evidence of multiplication
in the intestinal tract, and then I shall be able
to digest his interesting data a little better.
DR. ARMSTRONC: I cannot absolutely say as
to multiplication, but I was able to recover it
from the intestinal tract, after considerable time.
DR. Cox: I wish to ask whether they become
immune.
DR. ARMSTRONG: In seven or eight days they
become immune, completely immune.
CHAIRMAN ANDERSON: He said was there an
immunity in the mice.
Are there any further comments? Dr. Voroshilova.
DR. VOROSHILOVA (through an interpreter):
The experiences and observations regarding
these questions concern the immunizations which
were conducted in Moscow.
We had to choose children of more advanced
age, because the virus was not influenced by
preceding immunity. Here we took eight strains
which had been excreted by four children, triplepositive,
from Karaganda 3-10 days after their
feeding, and after four and five weeks, respectively.
In another research, which we conducted in
the Estonian Republic, the strains of Type 3
were excreted by small children who had no
antibodies.
In the third research, we had strains T- from
children up to three years of age who had been
in contact with immunized children.
Among these strains we noted multiple variations;
the strains which were excreted in Karaganda
from the older children, in general, had
T- marker,