Modification of hemopoietic stem cells of BALB/c mice by Rauscher leukemia virus

Bone marrow and spleen from Rauscher leukemia virus (RLV) infected BALB/c mice were tested for proliferative activity at various time intervals after infection using the spleen colony assay. Both bone marrow and spleen derived colonies showed a modified maturation behavior. The erythroid colonies were classified into three consecutive stages of maturation according to morphologic criteria. Both bone marrow and spleen derived erythroid colonies exhibited a retardation of maturation upon RLV infection of the donor mice; the spleen derived erythroid colonies showed the most severe changes. RLV itself could not mimic this phenomenon; moreover it was shown by immunofluorescence that only low amounts of RLV were present in the spleen colonies. It is therefore suggested that RLV modifies part of the stem cell compartment leading to a prolonged cycle time of proerythroblasts and hence to a retardation of colony growth.