LIVE POLIO IRUS VACCINES

Development and Persistence of Polio Antibodies in Young Adults 237
TABLE 5. RESIDUAL VIRUS ACTIVITY IN SAMPLES DRAWN IN DIFFERENT TIME PERIODS FROM VIRUS-
SERUM MIXTURES CONTAINING 1:100 DILUTIONS OF SERA TAKEN IN 18/HB 14 DAYS AFTER TYPE 3
ATTENUATED VIRUS WAS FED (S-5) AND 10 WEEKS LATER (S-10)
INCUBATION
OF THE
VIRUS-SERUM
MIXTURE
VIRUS
CONTROL
FIRST EXPERIMENT
S-5 S-10
VIRUS
SECOND EXPERIMENT
CONTROL S-5 S-10
1 hour 3,3 3,1 3,1 3,7 3,3 3,3
3 hours 3,5 3,2 2,7 ND ND ND
6 hours 3,2 3,0 2,3 3,3 3,1 2,3
24 hours 3,2 3,0 1,7 2,9 2,8 1,5
NOTE: The samples were diluted immediately after drawing in tenfold steps and ten tissue-culture tubes
were inoculated from each dilution.
tion of whether the nature of the change was
a quantitative, rather than a qualitative one.
We followed the RVA in mixtures containing
approximately 1035 . TCDso of virus per 0.1 ml.
and the final dilution 1:40 of serum taken before
the feeding of virus (S-1) and the 14th day after
feeding (S-5). After one, three, and six hours
of incubation at 370 C. samples were drawn and
diluted as described previously. The results of
two repeated experiments are presented in
Table 6.
The results suggest that there is a difference in
the neutralizing capacity of both sera. The first
serum specimen reduced the virus titer by 90
per cent with the second reducing the titer by
99 per cent after six hours incubation. The differences
of this order are large enough to be
demonstrated by IIT, where the final concentration
of virus in the inoculum is 10 TCD,,, but too
small to be demonstrated by the end-point technique
with 100 TCD,, in the CP/6 or in the pH
tests.
DISCUSSION
Our results indicate marked variations in antibody
response after feeding of Type 3 attenuated
poliovirus in
different subjects and different
tests. CP/1 was demonstrated as the least sensitive
and in some cases was quite inadequate for
detecting the antibody response.
The results
achieved show how misleading any conclusions
based on this one test may be.
TABLE 6. RESIDUAL VIRUS ACTIVITY IN SAMPLES DRAWN IN DIFFERENT TIME PERIODS FROM VIRUS-
SERUM MIXTURES CONTAINING 1:40 DILUTION OF SERA TAKEN IN 1/HB BEFORE TYPE 3 ATTENUATED
VIRUS WAS FED (S-1) AND ON THE 14TH DAY AFTER FEEDING (S-5)
INCUBATION
OF THE
VIRUS-SERUM
1 hour
VIRUS
FIRST EXPERIMENT
S-1 S-5
VIRUS
SECOND EXPERIMENT
CONTROL
CONTROL S-1 S-5
_ - - - ' ~ I-IlI - - - - -'-I
3,8
3,6 3,8 3,3 3,1
3,1
3 hours 3,9 3,1 2,8 ND ND ND
6 hours 3,7 2,8 2,0 3,4 2,8 1,7
NOTE: The samples were diluted immediately after drawing in tenfold steps and 10 tissue-culture tubes
were inoculated from each dilution.