LIVE POLIO IRUS VACCINES

10. LABORATORY INVESTIGATIONS OF THE ATTENUATED
POLIOVIRUS VACCINE STRAINS. II. TISSUE CULTURE
CHARACTERISTICS BEFORE AND AFTER
GASTROINTESTINAL PASSAGE
SAMUEL BARON, ROBERT M. FRIEDMAN, RUTH L. KIRSCHSTEIN, GERALD L. BORMAN,
RODERICK MURRAY, AND GEORGE A. HOTTLE
Division of Biologics Standards
National Institutes of Health, Bethesda, Maryland
DR. BARON (presenting the paper): Low neurovirulence
for primates is considered a prerequisite
for virus strains to be used in live poliovirus
vaccines and indeed, the presently proposed
strains were selected on this basis. An additional
requirement is stability of the low neurovirulence
characteristic during vaccine production
and human passage. Studies of the neurovirulence
of vaccine strains and of stability of
their neurovirulence characteristics have been
reported by many workers.' These studies, however,
have often given rise to quite different conclusions.
Studies have been reported from our
laboratory in which an effort was made to obtain
under standardized conditions, comparative information
concerning the neurovirulence for monkeys
of the various vaccine strains presently
proposed. 2 ' 3 The present report concerns cur-
rent studies of stability of the neurovirulence
characteristics during laboratory and human passage
of vaccine strains.
Material and Methods. Vaccine strains were
obtained from Drs. Koprowski, Cox, and Sabin
and are listed with their titers as determined in
our laboratory in Table 1.
Stool samples were obtained either as whole
stool or suspensions. Stools from contacts of
persons fed Koprowski Type 1 virus were obtained
from Dr. M. Shár in Switzerland; Sabin
Type 3 stools, from Dr. C. H. Stuart-Harris in
England; and stools containing Lederle Types 1,
2, and 3 strains from Dr. Flipse and Dr. Erickson
in Miami, Florida. Ten per cent stool suspensions
were passed through a Swinney filter containing
a Seitz pad which had been pre-treated
with tryptose phosphate broth. Stools from per-
KOPROWSKI
GROUP
TABLE 1.
STRAINS OF POLIOVIRUS STUDIED
TYPE
TYPE
TYPE
TYPE
1
1
II
III
LEDERLE GROUP
TYPE
TYPE
TYPE
TYPE
1
1
II
III
SABIN GROUP
TYPE I
TYPE II
TYPE III
WISTAR-CHAT POOL 13
WISTAR WIP-1 POOL 1
TN 19 POOL 1
WFX POOL WY 13
LEDERLE-SM, # 7-1231-166
LEDERLE-SM, # 7-1231-114
LEDERLE-MEF-1, # 7-1232-243
LEDERLE-FOX, # 7-1233-344
L SC, 2 AB
P 72, CH, 2 AB
LEON, 12 A, B
124
107
107.4
106.0
107.1
T
.10
PFU/ML
PFU/ML
PFU/ML
PFU/ML
107.9
PFU/ML
6 4
106 PFU/ML
6
1 5 PFU/ML
107.0 PFU/ML
PFU/ML
PFU/ML
PFU/ML