LIVE POLIO IRUS VACCINES

232
Efficacv-Laboratory Evidence
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- cPr with 4 hour mncubation - piHT wm 4 hcur ,ncuboton I!T
-CPT wiih 6 hours incubation ------pHT vih 6 hurs incubction
FIG. 3. The development of Type 3 antibody measured by different neutralization tests in young adults
without preexisting serological immnunity, fed with 100,000 TCD4o of Type 3 attenuated virus.
in the further course became lower. After the
fourthweek,when the pH antibodies reached their
highest levels, they began to drop, while still
later a certain increase in CP antibodies could
be observed (subjects 18/HB, 16/HB, 4/HB).
On the other hand, in three other subjects, antibodies
detectable in CP/1 persisted for a relatively
short period and in one subject no antibodies
could be demonstrated by means of this
test at all, in spite of a good virus multiplication
in the alimentary tract.
In all cases investigated, antibodies to Type 3,
at least in some of the tests used, were demonstrable
after the 12-week period.
In subjects possessing homologous serological
immunity the antibody response was not faster
than in non-immunes (Fig. 4). The antibody
increases usually appeared between the 10th to
14th day after feeding of the virus. However,
when comparing the results obtained in these
individuals to those obtained in non-immune
persons, some other marked differences can be
demonstrated.
In four out of seven subjects investigated, only
a transient increase in homologous antibody
could be detected. Only in one subject (22/HB)
did the antibody increase in pH tests and CP/6
precede the antibody increase in CP/1. In subject
1/HB, antibody increase was demonstrated
only in CP/1 and IIT (1/HB), and in
another subject the antibody increase in CP/1
preceded the antibody increase demonstrable in
other tests. In the remaining subjects, a simultaneous
increase of antibody titers was observed
in all tests used. Furthermore, the antibody
titers estimated in CP/6 in these subjects-except
case 22/HB-were usually on the same level as
in pH tests and the titers in IIT were in all
cases higher than in any one test performed with
100 TCD 50 .
(b) Heterotypic antibody response.
The results obtained in studying the heterotypic
antibody response are presented in Fig. 5.
The antibody response to Type 2 was found in
11 out of 15 cases, and persisted in eight after
the 12-week period. Type 1 antibody increase
was observed in 11 cases too. Only in six cases,
however, was it detectable at the end of the observation
period.
As for the time of appearance, in one case
the increase in Type 2 antibody preceded the
homotypic antibody response. In two cases, a
simultaneous rise against all three types was observed;
in two other cases it was observed simul-