LIVE POLIO IRUS VACCINES

7. LABORATORY INVESTIGATIONS OF THRE ATTENUATED
POLIOVIRUS VACCINE STRAINS
I. NEUROVIRULENCE AFTER INTRAMUSCULAR INOCULATION OF
MONKEYS
R. KIRSCHSTEIN, G. BORMAN, S. BARON, R. FRIEDMAN, R. MURRAY, AND G. HOTTLE
Division of Biologics Standards
National Institutes of Health, Bethesda, Maryland
DR. KIRSCHSTEIN (presenting the paper): At
the First International Conference on Live Poliovirus
Vaccines last year we presented a comparison
of the neurovirulence of the attenuated poliovirus
vaccine strains when inoculated directly
into the central nervous system (CNS) of monkeys
1. As you heard this afternoon, Dr. Pette
confirmed our observations.
The significance of those results and the correlation
of neurovirulence after that type of inoculation
with neurovirulence in man is not
really known. Therefore, it appeared that a
study of the neurovirulence of the attenuated
strains after inoculation extraneurally might be
more meaningful and add to our knowledge of
the invasiveness of these strains.
Preliminary studies of these strains after intramuscular
inoculation have been performed
before by Sabin in 1957 2 and by ourselves and
Melnick in our laboratory 3 in 1958.
Monkeys: The majority of monkeys used in
this study were Rhesus (Macaca mulatta). A
small number of Cynomolgus (Macaca irus phillipinensis)
monkeys were also used. The animals
were in overt good health and weighed
between 4-10 lbs. initially. The animals were
observed daily for signs of poliomyelitis and
were sacrificed at 14-20 days. They were housed
in stainless steel double-decked cages with 2 or
3 per cage.
Virus strains: The virus strains were obtained
from Dr. Koprowski, from Lederle Laboratories
and from Dr. Sabin. The titers and identification
of the virus strains are seen in Table 1.
The virus fluids were titered as described in
our paper at the first Conference. On the whole
the titers were somewhat higher than those we
obtained last year.
Inoculation: The monkeys were inoculated
into the right thigh, or upper arm muscles with
1 ml., 5 ml., or 10 ml. amounts of undiluted
virus fluids or 1 ml. amounts of material diluted
1:10.
Examination o! Tissues: The methods followed
were those used in the safety test for inactivated
poliomyelitis vaccine and were de-
TABLE 1.
STRAINS OF POLIOVIRUS STUDIED
Koprowski group
Type 1
Type 2
Type 3
Lederle group
Type 1
Type 2
Type 3
Sabin group
Type 1
Type 2
Type 3
Wistar-CHAT Pool 13
TN 19 Pool 1
WFX Pool WY 13
Lederle-SM, y 7-1231-166
Lederle-MEF-1, M& 7-1232-243
Lederle-Fox, M 7-1233-344
L Se, 2 ab
P 72, Ch, 2 ab
Leon, 12 a, b
107.2 PFU/ml.
106'o PFU/ml.
10' M 1 PFU/ml.
107.9 PFU/ml.
106 ' 5 PFU/ml.
107.0 PFU/ml.
107'7 PFU/ml.
107 T 3 PFU/ml.
1079 PFU/ml.
90