LIVE POLIO IRUS VACCINES

Development and Persistence of Polio Antibodies in Young Adults 231
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>1 ps
K
cg,
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9-
8-
2 3 5 7 2 3 5 7 2 3
TIME AFTER INOCULATION
IN DAYS
FiG. 2. The mean antibody titers estimated in 2, 3, 5 and 7 day readings in the control titrations of
reference serum in CP/1 and CP/6 tests.
the fifth-day reading. Figures 1 and 2 show the
relation of the virus and antibody titers in CP/1
and CP/6 to the time of reading. The results
demonstrate an increase in virus titers and a
decrease in antibody titer in the course of seven
days. In a log/log plotting of time (day of
reading) the relation is nearly linear for both
the virus and antibody titers. The decrease in
antibody titer proceeds equally in CP/1 and
CP/6, as can be observed from the parallelism
of the lines.
Results of the investigation of virus excretion
in vaccinated individuals. Table 3 indicates that
in all eight individuals lacking homologous antibodies,
Type 3 virus was excreted for up to six
weeks after the administration of the virus. Seven
out of 14 cases possessing Type 3 antibodies
excreted Type 3 virus, mostly in lower titers and
for a shorter period of time than the nonimmunes.
In one subject excreting no Type 3
virus, Type 2 virus was isolated from a stool
sample taken on the 35th day after virus was fed.
Results of the serological investigation performed
in subjects excreting the virus.
(a) Homotypic antibody response.
Figure 3 shows that the homotypic antibodies
to Type 3 were detected seven to 14 days after
feeding of the virus. In six out of eight investigated
persons without pre-existing homologous
seroimmunity it was possible to demonstrate antibodies
sooner in the CP/6, pH, and IIT tests
than in the conventional CP/1 test. In one of
the two remaining cases, the seven and 10-day
samples were not available; in the second one,
pH tests were not performed. The titers of antibodies
achieved in CP/1 were in all cases on the
lowest level.
Antibodies in CP/6 appeared simultaneously
or later than the antibodies in pH tests and
their levels, in most cases, were significantly
lower than in pH tests. Titers achieved in the
IIT were in all cases higher than in the CP/6,
but usually on the same level as in pH tests. In
subject 18/HB, in which the most considerable
differences between CP and pH tests were
demonstrated, the antibody titers in IIT were significantly
lower than in pH tests.
In some cases, the highest differences in antibody
titers achieved by different tests were found
in the first phases of antibody development, and