MURINE LEUKEMIA-VIRUS INFECTS EARLY BONE-MARROW PROGENITORS IN IMMUNOCOMPETENT MICE

Chronic murine leukemia viruses (MuLVs) are retroviruses which induce leukemias/lymphomas after long latency periods. The induction of leuke mia by MuLVs is complex, requiring multiple steps beginning with infec tion of an appropriate target cell. A number of investigators have pro posed a bone marrow-thymus axis in the development of retrovirus induc ed T-cell lymphoma in which cells are initially infected in the bone m arrow. These bone marrow cells or their progeny migrate to the thymus during the disease process. In our system using adult, immunocompetent BALB.K mice infected with E-55(+) MuLV, a similar pattern is seen; in tegrated virus is initially detectable in the bone marrow and spleen a nd only later in the thymus. In order to better understand the leukemi c process, we analyzed the bone marrow from adult, immunocompetent BAL B.K mice infected with the E-55(+) MuLV in bone marrow colony assays. The results from these assays demonstrate that either a pluripotent pr ogenitor cell or an early progenitor cell is a target in the bone marr ow for the virus. (C) 1996 Academic Press, Inc.