vlRoLocY
66.327-329
(1975)
Properties
of Mouse
Leukemia
IX. Active and Passive Immunization
Viruses
of Mice Against Friend Leukemia
with Isolated Viral GP,l Glycoprotein
and Its Corresponding
Antiserum GERHARD HUNSMANN,’ Max-Planck-Znstitut
VOLKER MOENNIG,2 fir
Virusforschung,
Accepted
March
AND
TUbingen,
WERNER SCHAFER Germany
4, 1975
Mice could be protected against Friend leukemia virus-induced leukemia by inoculation with the major viral glycoprotein GP,, or its antiserum.
Recently, the major surface glycoprotein (GP,,) of Friend leukemia virus (FLV) was purified to a high degree of homogeneity (1, 2). Specific antisera prepared against this component possessed strong neutralizing capacity (3), demonstrated in immuno electron microscopy the presence of GP,, antigen on the surface of budding virus as well as on other areas of the host cell outer membrane and showed complementdependent cytotoxicity for virus-producing cells at high dilutions (4). Thus GP,, and its antiserum appeared as promising candidates for active and passive immunization of mice against virus-induced leukemia. In this communication some preliminary results supporting this concept will be described. Highly inbred male mice of the low leukemic STU strain were used throughout. Physicochemically and serologically pure GP,, was prepared according to methods described earlier from FLV produced in a permanent line of STU mouse cells (2). Plaque-forming units (PFU) of FLV were determined in the XC test (3). For active immunization vaccines were prepared by emulsifying GP,, in complete 1Present address: Forschergruppe Tumorimmunologie, FreiburgBrsg. ‘Present address: Inst. fir Virologie Tierlrztiiche Hochschule. Hannover.
or incomplete Freund adjuvants. Freund adjuvant had been proved to be very effective in producing GP,, antibodies in other animal species (3). Mice were inoculated with the vaccine at multiple sites at 12 weeks of age and boostered 4 weeks later. One week after boostering they were challenged by intraperitoneal injection of a cell-free filtrate (0.2 ml) of an extract (l%, w/v) prepared from FLV-leukemic mouse spleens containing 1.4 x 10’ PFU/O.2 ml. Four weeks after challenge the mice were killed, their spleen weights measured and the virus titers of some of the sera and spleen homogenates determined. The results of two experiments (Experiment A with complete and experiment B with incomplete Freund adjuvant vaccine) are presented in Table 1 and Fig. 1. That the spleen weight of the murine leukemia virus (MuLV)-infected mice can be influenced by the mere inoculation of Freund adjuvant is known from other studies (5) and was also observed in our experiments (compare Table 1, Expt. A 7, 8, Expt. B 2, 3, and Fig. 1). However, in Experiment A as well as in B, in addition to this decrease in average spleen weight, a further decrease was observed when the vaccine contained a sufficient amount of GP,, (90 and 120 pg, respectively). Because of a shortage in material we could not
327 CopyrIght 0 All rights of
1975 by Academic Press, Inc. reproduction in any form reserved.
328
SHORT
COMMUNICATIONS TABLE
ACTIVE
IMMUNIZATION
OF STU
MICE
1
WITH ISOLATED FLV-GP,,
USING COMPLETE
AND INCOMPLETE
FRNJND
ADJUVANTD
Experiment
A
B
Series No.
1 2 3 4 5 6 7 8 9 1 2 3 4
GP,,/ mouse be;)
Adjuvant
90 9 9.10-I 9.10-J 9.1o-5 9.10-7 120 -
CFA CFA CFA CFA CFA CFA CFA CFA IFA IFA IFA
IfInmald with FLV
Number of mice inoculated
+ + + + + + + + + + + -
8 8 8 10 9 9 9 8 10 5 5 5 5
Spleen weight bid Average 233 583 470 450 850 722 430 1,254 73 164 566 1,050 62
PFU in pooled Serum
(r m 23 179 96 111 136 112 118 111 7 13 253 215 7