Change in marrow and spleen CFU compartments following leukemia virus infection: comparison of Friend and Rauscher virus.

The effects of the Friend and Rauscher leukemia viruses on the marrow and spleen colony-forming unit compartments have been studied. It was found that the two viruses produced qualitatively similar but quantitatively different #{224}(ffectsrelative to each other. Comparison of the effects of the individual virus on spleen with those on the marrow also showed striking differences. In the spleen by 14 days after infection with either virus the CFU compartment was grossly enlarged. In the marrow of the Friend-infected mouse the CFU number was not significantly different from normal, and jn the Rauscher-infected mouse there was a 50% drop in marrow CFU. Measurement of the F factor showed that infection by either virus resulted in colony-forming units that were deficient as compared to the normal in their ability to successfully “seed” in the spleens of irradiated normal recipients, with the greater depression in F factor being found in cells obtained from spleen tissue. These results indicate that in both cases the natur#{233}of the host tissue (marrow versus spleen) exerts a significant modifying effect on the expression of the virus action, and also suggest that the pluripotent colony-forming unit may be a target cell for these viruses.