A replication-competent murine leukaemia virus that causes an erythroblastosis-like leukaemia, in which there are large numbers of nucleated red cells in blood. Appears to induce tumours by insertion into the proviral integration site, Fli-1, on mouse chromosome 9. Friend helper virus is a murine lymphoid leukaemia virus originally thought to assist replication of Friend virus. Friend murine erythroleukaemia cells (Friend cells) are erythroblast lines transformed by the virus that can be induced to differentiate in vitro, as shown by the production of haemoglobin. Friend spleen focus-forming virus is a defective virus found in some strains of Friend helper virus. Will form foci in infected mouse spleen and the leukaemia is associated with polycythaemia rather than anaemia.
Subjects: Medicine and Health.