LIVE POLIO IRUS VACCINES

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Discussion
if we give the Blacksburg Newcastle vaccine
(4.5 logs or better), either intranasally or in the
eye, we find that they are rendered immune. I
think this observation is an extremely important
one and of value in polio work.
Actually, the work which was done on Newcastle
disease back in 1944 and 1945 by my colleague,
Dr. Floyd S. Markham, highly influenced
us to go in the direction of living virus vaccine
in connection with the polio problem.
DR. LÉPINE: I should like to confirm what Dr.
Perkins said regarding the response of infants to
antigenic stimuli, especially in the case of inactivated
vaccine.
A paper published recently by Dr. R. Grumbach
et al., containing a study made with my
laboratory's participation and presented at the
October meeting of the C.I.E. in Paris, shows the
response of infants immunized with inactivated
polio vaccine combined with other antigens,
namely, diphtheria, tetanus, and pertussis on
two groups of children. In one group, there were
infants from two to six months of age; in the
second, children over six.
After immunization, the response in infants,
as judged by the antibody titers obtained, seemed
to lag behind that in the older ones, and it therefore
seemed at first that the results were not good.
However, one year later, when they were given
their booster dose, the infants' response jumped
to exactly the same antibody level as that of the
older children. So, even if the primary response
in infants is not immediately so good as in the
older children, they nevertheless keep the memory
of the antigen and are later able to do as well
as the older children.
DR. KRUGMAN: I believe that the comments by
Dr. Lépine and Dr. Perkins tend to confirm our
impression that placentally transmitted antibody
masks evidence of active antibody formation. I
am reminded of a study which was carried out
in our department in 1952 by Doctors Osborn and
Dancis. Their studies were concerned with the
effect of passive transplacental antibody on the
active immunization of newborn infants with
diphtheria toxoid. An injection of toxoid was
followed by a rising titer of diphtheria antitoxin
in infants with low levels of passive antibody and
a declining titer in those with high levels.
At six months, infants with the high level of
transplacental passive antibody and lack of evidence
of response were given another inoculation
of diphtheria toxoid, which promptly induced a
"booster" response. Accordingly, it appeared as
if the initial high levels of passive antibody had
"masked" the presence of active antibody. This
phenomenon may explain the low percentage of
antibody response in our high titer group.
DR. DULBECCO: I should like to ask a question
of a more general nature, namely, what is the
feeling about the possible complication caused
by simian virus, some of which are known and
some possibly unknown, in the feeding of newborn
children?
In fact, the experimental work with animals
has shown that at this age animals are particularly
susceptible to carcinogenic viruses, of which
some are active also in oral infections.
CHAIRMAN HILLEBOE: Does anyone wish to
comment on this?
DR. KOPROWSKI: I should like first to comment
about immunologic tolerance. Although I recognize
this phenomenon as an important biological
problem, we have no evidence that it plays any
role in virus infection, except possibly the
lymphocytic choriomeningitis infection of mice.
Even in that case, the available evidence is still
not completely satisfactory because the crucial
experiments have not been performed.
I must say that we have completed a two-year
study of attempts to induce tolerance in mice to
the three viruses: rabies and two Arbor B viruses.
If these observations are ever written up, they
will be submitted to the "Journal of Negative
Results."
If we want to study tolerance in virus diseases,
our efforts should be directed to infections which
do not induce formation of demonstrable antibodies,
such as African swine fever, equine infectious
anemia, or serum hepatitis. Our efforts
are largely wasted in the case of diseases like
poliomyelitis, where antigenic stimulus almost
invariably causes antibody formation.
In one case of possible fetal infection of man,
that of German measles virus, tolerance does not
play any role. 1 have asked Sir Macfarlane Burnet
on several occasions about children who were