CHARACTERIZATION OF MOUSE MAMMARY-TUMOR VIRUSES PROPAGATED IN HETEROLOGOUS CELLS

Abstract

Mouse mammary tumor viruses (MMTV) from 3 strains of mice were used to establish productive infections in feline and mink cell lines. The virions that are released by these cells compete completely in a radioimmunoassay for the major virion surface glycoprotein of MMTV (gp52), thus demonstrating that antigenic determinants of gp52 are viral coded. Competitive molecular hybridization studies showed that the 60-70 S RNA of MMTV propagated in feline cells contain all the nucleic acid sequences found in 60-70 S RNA from MMTV synthesized by murine cells. The virion buoyant densities in sucrose and CsCl virion sedimentation coefficient, divalent cation requirement of the virion DNA polymerase and morphology of MMTV synthesized in heterologous cells are similar to those of MMTV grown in murine cells. Cultures of MMTV-infected feline cells continuously released between 0.1 and 1.0 .mu.g of virus/107 cells (75 cm2 flask) per day during the 60 wk observation period. No detectable feline or murine type C viruses were produced by these cultures.