Studies on friend virus‐induced viremia in lethally irradiated mice with or without hematopoietic repopulation

No detectable viremia was recovered from supralethally irradiated mice which had been infected with Friend Leukemia Virus (FLV) although large amounts of virus were recovered from non‐irradiated control mice. When irradiated mice were repopulated with either spleen or bone‐marrow cells from syngeneic donors and then infected with FLV, viremia was readily detectable in these hosts, both by electron microscopy and by bioassay into susceptible mice. In similarly irradiated mice given thymus cells, however, no virus was detected by titration although extremely rare particles were observed in the plasma pellets examined by electron microscopy. These data indicate that the appearance of virus in the plasma depends upon the presence in the infected animals of FLV target cells, found primarily to be the hematopoietic components of both bone marrow and spleen.