A human breast tumor cell line (BT-474) that supports mouse mammary tumor virus replication

A human breast tumor cell line BT-474 derived from an invasive ductal carcinoma was experimentally infected in vitro with a mouse mammary tumor virus from the TIII strain (RIII-MuMTV). The virus that replicated in the human cells was characterized as a mouse virus by immunofluorescence, electron microscopy and the presence of a specific RNA-directed DNA polymerase. The cells themselves were human as per the karyotype and isoenzyme migration patterns. It is concluded that human cells are susceptible to the mouse mammary tumor virus and can, eventually, support its replication.