LIVE POLIO IRUS VACCINES

who had no antibody at all, as demonstrable by
the tube neutralization test, the heterotypic response
was of a very low order, below 1:16.
If the tests were carried out beyond four weeks,
persistence of the low level response was rare.
I should like to ask Dr. Horstmann a question
for the record, and that is whether the search for
other enteric viruses in these children was carried
out only in monkey kidney or also in a
human cell line and newborn mice?
DR. HORSTMANN: All of the pre-vaccinal specimens
were tested in monkey-kidney cells and
Hep.-2 cells. We did not use infant mice.
DR. SABIN: I should like to point out that in
our own experience the infant mice contributed
very little to the total. Only about 2 per cent of
the viruses from children in Mexico that we could
not isolate in monkey kidney and Hep.-2 cells,
were recovered in infant mice; therefore, my
Discussion 123
Discussion 123
reaction to the question I just asked is that
probably most of the enteric viruses that are
detectable by available methods were detected
here.
DR. HORSTMANN: Yes.
DR. PLOTKIN: I wonder if Dr. Horstmann, or
anyone else, has reinfection data after trivalent
vaccine. The question in my mind, of course, is
whether the relative resistance which has been
observed after feeding monovalent vaccine would
be equally observed after trivalent vaccine.
DR. HORSTMANN: Later Dr. Paul will give results
on revaccination with trivalent vaccine.
CHAIRMAN ZHDANOV: We shall now proceed
with Dr. Baron's paper on the "Laboratory Investigations
of the Attenuated Poliovirus Vaccine
Strains."