Host range of murine sarcoma virus, its host modification and phenotypic mixing with endogenous virus

The M(MSV)AG-50 cells produce competent ecotropic sarcoma virus which is able to transform several rodent embryo cells and replicate in them. The expanded host range has shown that the virus acquired some host information which facilitate the transformation of heterologous cells. The transformed cells were XC positive and with transformed phenotype in vitro. The genome of mouse sarcoma virus from nonproducer rat liver cells could be rescued by xenotropic endogenous virus. The obtained virus has shown the augmented host range for various embryo cells and for some mammalian cell lines as well. The virus with xenotropic coat efficiently transforms the cells, yielding cells with transformed phenotype. The majority of this virus were phenotypically mixed virions, with minority of probably recombinant virus as suggested by XC test. The modification of the virus during the passage through heterologous cells is discussed.