Effect of a Mouse Mammary Tumor Virus-Derived Protein Vaccine on Primary Tumor Development in Mice 1,2

ABSTRACT-The vaccines used in this study were derived from purified murine mammary tumor virus (MuMTV) preparations. Approximately 60 % of the protein fractions consisted of the major viral membrane glycoprotein gp52. Inoculation sc of 10 pg MuMTV-S-derived vaccine significantly delayed the appearance of primary mammary tumors in GR and BALB/cfC3H mice (strains with high incidences of mammary cancer); in BALB/c and C3Hf mice, which have a moderate tumor incidence at an advanced age, this treatment resulted in a slight and substantial accelera-tion, respectively, of primary tumor development. The induced cellular immune reactivity for vaccination, as measured with the in vivo Winn test and the in vitro leukocyte adherence inhibition assay, was strongest in the GR strain as compared to the BALB/c strain. The titer of antibodies to tumor cells, as estimated by membrane immunofluorescence, was also highe