Reconstitution of the W/Wv stem cell differentiation defect by XXXX virus.

@entity19 @entity1778 @entity2131 @entity18903
Hematopoietic stem cells of W/Wv @entity19 failed to produce macroscopically visible hematopoietic spleen colonies in irradiated recipient @entity19 . Infection of W/Wv @entity19 of the @entity18903 -susceptible genotype Fv-2ss (DBA/2) or Fv-2rs (BD2F1) with @entity1778 virus (RLV) restored the spleen colony-forming capacity of the stem cells. The resulting spleen colonies had normal size and cellularity; the frequency of and ratio between granulocyte-macrophage and erythroid progenitor cells were also normal, without excessive production of erythroid cells. The frequency of spleen colony-forming units (CFU-S) appeared to be strongly reduced in W/Wv @entity19 . The seeding fraction of RLV-infected W/Wv stem cells in the recipient spleens did not differ from that of uninfected or RLV-infected +/+ stem cells. At equivalent numbers of CFU-S, spleen suspensions of RLV-infected W/Wv @entity19 were equally effective as +/+ control suspensions in protecting irradiated @entity19 from death due to @entity2131 . Thus the number of CFU-S observed appeared to be predictive for the number of W/Wv cells required for effective radioprotection. In irradiated W/Wv @entity19 that received transplants of RLV-infected W/Wv cells, circulating erythrocyte numbers approached those of control @entity19 ; the erythrocytes were of normal size, in contrast to the macrocytic red cells of untreated W/Wv @entity19 . The reduced frequency of CFU-S in RLV-infected W/Wv @entity19 can be readily explained by a reduced self-replicating capacity, attributable to the W/Wv genes, which was not reconstituted by infection with RLV. The data indicate a direct involvement of pluripotent stem cells upon infection with RLV.
