Assignment of the receptor for ecotropic murine leukemia virus to mouse chromosome 5

Identification of host factors that regulate leukemia virus replication and expression is an important feature in understanding virus-host interaction. One host gene, Fv-1, which regulates ecotrepic (mouse-tropic) murine leukemia virus (MuLV) ' replication, has been assigned to chromosome 4 in the mouse, closely linked to the enzyme glucose-6-phosphate dehydrogenase (1). This factor operates at a postpenetration step (2, 3) and may influence integration of proviral DNA into the host chromosome (4, 5). Additional host control is exerted at the level of differentiation. One example is the ability of bone marrow derived but not thymus-derived lymphocytes tosupport replication of exogenous MuLV (6). This restraint may be distinct from, or identical to, that which is influenced by the viral receptor. Huang et al. (2) demonstrated that whereas mouse cells absorbed pseudotype virus particles consisting of vesicular stomatitis virus (VSV) cores with ecotrepic MuLV coats, Chinese hamster cells could not. Similar conclusions were drawn by DeLarco and Todaro (7) who studied the binding of labeled MuLV glycoprotein (gp 71) to mouse and Chinese hamster cells. This cellular capacity is most likely under the control of a cell structure known as the ecotropic MuLV receptor