LIVE POLIO IRUS VACCINES

84
Safety-Laboratory Evidence of Attenuation and Safety
mediately available to us. These tests are being
confirmed with certified sera. Vacuolating
virus strains 776, 175, 953, 1095, and 584 were
neutralized by pooled antiserum against Hull's
group 1 B (S.V. 20, 23, 25, and 27) and the
last three strains by group 3 (S.V. 12, 28, 59).
None was neutralized by group 2 (S.V. 2, 16,
18, 19) or group 4 (S.V. 5, 6, 29) antisera. In
these tests, only a negative finding has significance
since the antisera employed were prepared
using virus grown in Rhesus or Cynomolgus kidney-cell
cultures, which might also have contained
vacuolating virus.
Host cell range. Vacuolating virus strain 776
titering 10 - 50 ° in green monkey-kidney culture
was tested in the various primary and line cell
cultures shown in Table 3. No definitive cytopathic
change referable to the virus was observed
in any of these cultures, other than
green monkey kidney, when observed for 8 to
12 days. The virus was shown to persist for at
least 10 days in HeLa or stable amnion cell cultures,
but without increase in titer. Titers as
high as 10- 8 5 have been obtained with vacuolating
virus propagated in green monkey-kidney
cultures.
Miscellaneous physical and biological properties.
Certain of the properties of the vacuolating
agent, not previously discussed, are
shown in Table 4. Studies are in progress to
determine the inactivation kinetics for the virus
with 1:4000 formalin in the Salk vaccine production
procedure.
TABLE 3. HOST CELL RANGE FOR CYTOPATHIC
EFFECT OF VACUOLATING AGENT STRAIN 776
KIND OF CELL
Primary Cell Cultures:
Green Monkey Kidney
Rhesus Monkey Kidney
Rabbit Kidney "t
Human Amnion "
Line Cell Cultures:
HeLa
Stable Amnion
Chang Liver
Girardi Human Heart
CYTOPATHOLOGY
Positive
Negative
TABLE 4. MISCELLANEOUS PHYSICAL AND
BIOLOGICAL PROPERTIES OF VACUOLATINC AGENT,
STRAIN 776
1. Filterable through Selas 03 and Seitz S1 filters.
2. Infected cultures fail to hemadsorb or cause
hemagglutination of guinea pig, chicken, or
human "O" erythrocytes at 4°C. or at 250C.
3. Resists treatment for 18 hours with an equal
volume of diethyl ether.
4. Infectivity destroyed by treating with 1:2000
formalin for 48 hours at 37°C.
5. Relatively heat stable. Heating at 56°C. for
one hour reduces infectivity titer about 30-fold.
6. Stable on storage at -20 0 C. and at -70°C.
7. Induces homologous neutralizing antibody in
rabbits immunized with the agent.
OCCURRENCE OF ANTIBODY AGAINST
VACUOLATING VIRUS IN HUMAN
AND MONKEY SERA
Tests of various human and monkey antisera
were carried out with the results shown in
Table 5.
None of the sera from six animals in two
lots of normal African green monkeys neutralized
the virus. Twelve of 18 antisera from normal
Rhesus monkeys neutralized the agent. This
included six monkeys especially caught, in India,
in a group of about 350 and flown to the U.S.A.
without ever being "gang-caged". The animals
were housed in single isolated cages after arrival
and tested eight months after receipt.
One lot of human gamma globulin was found
free of antibody when tested diluted 1:50.
Dr. Sabin sent us, for test, sera from five
children, each fed Sabin live poliovirus vaccine
Types 1, 2, or 3 on a total of six occasions and
sera from five normal children. None of these
sera showed antibody against the vacuolating
virus at a dilution of 1:5.
Tests were conducted with sera from 10 military
recruits in the first field trial 9 of adenovirus
vaccine at Fort Dix, N. J., in 1956. Three
of four recruits who had received two doses of
adenovirus vaccine showed antibody against the
vacuolating virus while none of six non-vaccinated
persons showed antibody. Tests of preand
post-vaccination sera from the same individuals
are currently in progress. Appearance
of antibody against vacuolating virus in such