Bioactivity of C3H and RIII Mammary Tumor Viruses in Virgin Female BALB/c Mice: Brief Communication 2

Abstract

The bioactivities of C3H and RIII mammary tumor virus (MuMTV) in virgin female BALB/c mice differed. The average number of mammary hyperplastic alveolar nodules per mouse after noduligenic tests was 20.1 in BALB/cfC3H and 10.7 in BALB/cfRIII females. Spontaneous mammary tumor incidence after 20 months of observation was 47.5% in BALB/cfC3H and 14.6% in BALB/cfRIII females (P less than 0.01). The frequency of lung metastases in mammary tumor-bearing mice was 63.1% in BALB/cfC3H and 16.6% in BALB/cfRIII females (P less than 0.05), although the clinical duration of mammary tumors was the same. These data demonstrated a lower bioactivity of RIII MuMTV when compared to C3H MuMTV in BALB/c mice and suggested that the causative virus may control all the steps of mouse mammary tumor development, including metastasis.

Development, Morphology, and Progression of Mammary Tumors During and After Fertile Life in BALB/cfRIII Mice<xref ref-type="fn" rid="fn2">2</xref>

“…The BALB/dRIII strain exhibits a low mammary tumor incidence in virgin females and a high mammary tumor incidence only in breeding females (8,10). Two possible explanations of this fact are: '1) A sustained replication of RIll MuMTV, which occurs only at pregnancy-lactation periods, is required to induce mammary tumors and 2) RIll MuMTV is oncogenic only when associated with the hormonal Mammary Tumors In BALB/cfRIII Mice 315 stimuli of pregnancy-lactation periods.…”

“…The BALB/dRIII mouse strain, which is of the BALB/c genotype and carries milk-transmitted RIll MuMTV infection initiated by foster-nursing (7), shows the following peculiarities: a) low mammary tumor incidence in virgins (8), b) high production of MuMTV during lactation periods (6,9), c) high mammary tumor incidence in breeders (10), and d) a large proportion of pregnancy-dependent "plaques" (11,12), i.e., plaque-shaped mammary tumors growing during pregnancies and regressing thereafter (13)(14)(15)(16). Plaques are true tumors because they attain palpable sizes, progress with time toward autonomy, and behave as malignant tumors (17,18).…”

Detection of Type-Specific Antigenic Determinants of Murine Mammary Tumor Viruses with Cell-Mediated Immune Assays

“…The differences in bioactivities are expressed as increased numbers of mammary hyperplastic alveolar nodules and higher incidence of mammary tumors in Balblc female mice foster nursed in C3H mice as compared to those foster nursed in RIII mice (9). An important aspect of those studies was the finding of a higher frequency of lung metastases in the Balb/ cfC3H mice.…”