Quantitative determination of mammary tumor virus in individual samples of mouse milk
Bistocchi, M.; Bevilacqua, G.; Nuti, M.
Tumori 63(6): 525-534
1977
ISSN/ISBN: 0300-8916 PMID: 203070 Document Number: 117870
Milk samples were obtained from mammary tumour virus (MTV)-free (BALB/c) and MTV-carrying (BALB/cfC3H and BALB/cfRIII) strains of mice on the 5th-8th days post partum. Partially purified MTV was prepared by 2 differential centrifugations followed by isopycnic centrifugation through a continuous 20-54% sucrose gradient. Optical density (260 nm) and protein concn. profiles were constructed for the gradients and fractions examined by electron microscopy. All gradient analyses revealed MTV concentrated in the zone of density 1.17 g/ml. Optical density measurement was preferred to protein concn. determination as a method of comparing MTV concn. in individual milk samples. Sensitivity and reproducibility were high when results were expressed in terms of total milk protein and MTV-free milk was used as a blank.