Genotype-limited changes in platelet and erythroid kinetics in Friend-virus-infected allophenic mice.

We report here results suggesting that cells of the megakaryocytic lineage or uncommitted precursor cells may be targets for Friend-virus-induced proliferation, and that genetic differences (other than Fv-2) between strains C57BL/6 and DBA/2 affect the susceptibility of these cells to Friend virus. The evidence suggesting this was derived from experiments with C57BL/6 in equilibrium DBA/2 allophenic mice. Within the first few weeks following infection of these mice with the polycythemic NB-tropic strain of Friend virus (FV-P), we observed a rapid shift in the genotypic composition of both red cells and platelets in favor of those of the DBA/2 genotype. Infection with the anemia-inducing strain of Friend virus (FV-A) also resulted in preferential production of DBA/2 strain erythrocytes, but its effect on platelet kinetics was nil. The FV-P- and FV-A-induced change in red cell composition is consistent with the view that erythroid precursors are target cells for Friend virus and that viral infection preferentially stimulates proliferation of susceptible strain (DBA/2) erythroid precursors. As for the platelet shifts induced by FV-P (and not FV-A), we believe the changes in platelet mosaicism also could be caused by viral-induced proliferation of DBA/2 platelet precursors, or more primitive progenitors, over the C57BL/6 ones. Thus, these results implicate the existence of nonerythroid target cells for FV-P-induced proliferation, as well as the existence of genetic differences between strains C57BL/6 and DBA/2 that modulate the responsiveness of such cells to infection.