LIVE POLIO IRUS VACCINES

Virological Findings, Antibody Response of Infants Fed Multiple, Oral Vaccine 271
at time of birth and a second blood specimen will
be taken from the infants when they reach the age
of six months.
Oral poliomyelitis vaccine. Individual doses of
trivalent oral vaccine, "Orimune", lot No.
7-1238-804A, in vials containing 2 ml., kindly
supplied by the Lederle Laboratories, Pearl
River, New York, were used for feeding. Prior
to feeding, the vaccine was titrated for whole
virus content and found to contain 106.2 TCD,,
per dose. Since Type 2 poliovirus was found
to be absent in numerous post-feeding stool
specimens tested, a titration was carried out for
the quantitative estimation of the poliovirus types.
The trivalent vaccine was found to contain:
Type 1-105.7 TCD 50 , Type 2-104.2 TCD 5 ,,, and
Type 3-106.2 TCDo 0 .
A new lot of poliomyelitis oral vaccine, No.
7-1238-812A1, was received in March 1960. Titration
for whole virus content showed 1003 TCD5o
per dose. Titration for estimation of the individual
type concentrations showed: Type 1-10`2,
Type 2-105':, and Type 3-105'". The new lot of
vaccine is being used for refeeding of the infants
and continued feeding of newborns.
Laboratory studies. Virus isolations from stool
specimens: rectal swabs were collected in 2 cc.
medium consisting of Hanks' solution and 0.5 per
cent lactalbumin enzymatic hydrolysate. Specimens
were kept at -20 ° C. until used. For preparation
of the stool suspension, the swabs were
thoroughly rinsed in the medium and centrifuged
at 3000 rpm. for 20 minutes. The supernatant
fluid was decanted and antibiotics added as follows:
200 units of penicillin, 200 micrograms of
streptomycin, and 100 units of mycostatin per
ml. of stool suspension. Monkey-kidney cell
cultures (MKCC) were prepared from Rhesus
monkeys in growth medium consisting of Hanks'
solution, 0.5 per cent lactalbumin enzymatic
hydrolysate, 2 per cent calf serum, and 0.22 per
cent sodium bicarbonate with a final pH of 7.6.
Stool suspensions, in 0.2 cc. amounts, were inoculated
into three MKCC tubes and observed for
CPE for a period of seven to 10 days.
Identification of strains. Pre-feeding stool
specimens showing CPE were typed by the neutralization
test using immune sera against poliovirus
Types 1, 2, and 3, ECHO virus Types 1-14.
Coxsackie B virus Types 1-5, and Coxsackie A9.
The immune poliovirus horse sera were kindly
supplied by Dr. V. J. Cabasso, Lederle Laboratories,
New York. Post-feeding cultures showing
CPE were carried through neutralization tests,
using pooled pairs of poliovirus immune sera.
Specimens containing mixtures of polioviruses
with other previously identified enteroviruses
were typed by adding the immune serum of the
identified enterovirus to the pooled pairs of immune
poliovirus sera.
Antibody tests. Neutralization tests were carried
out on the pre- and post-feeding sera simultaneously.
All sera were inactivated for 30
minutes at 56 ° C. prior to testing. The serum
samples were then prepared in fourfold dilutions.
Approximately 100 TCD,, per 0.25 ml. of poliovirus
Types 1, 2, and 3, respectively, were added
to an equal volume of the respective serum dilutions.
The mixtures were incubated at 37 ° C. for
two hours and then inoculated into MKCC tubes.
Results were recorded after seven days of incubation
at 37 ° C.
RESULTS
This preliminary report deals only with two
aspects of the study: (1) virological and serological
findings on 65 infants, three to four
months old, who had been given a single dose of
oral multiple poliomyelitis vaccine, and (2) effect
of naturally occurring enteroviruses on the
virological and serological response to the poliovirus
types fed, in 14 infants, one to four months
of age.
Table 1 is a summary of the virological findings
in the post-feeding stool specimens taken
from 65 infants, three to four months old, whose
pre-feeding stools were free from enteroviruses.
At first glance, the complete absence of Type 2
poliovirus is noted, while both Types 1 and 3
were repeatedly isolated from 71 per cent of the
infants. Failure to isolate any of the poliovirus
types fed occurred in only 6 per cent of the infants
examined. Isolation of a single type only
was found in 14 per cent for Type 3 and 9 per
cent for Type 1 poliovirus. A consideration of
the total number of infants who excreted poliovirus
Type 1 or Type 3, singly or in combination,
shows the percentage to be 80 for Type 1 and
85 for Type 3.