Cell Surface Receptors for Ecotropic Murine Viruses Are Different from Those for Xenotropic and Amphotropic Viruses

Abstract

The murine cell surface receptor for Rauscher murine leukemia virus was analyzed using a binding assay involving cultured murine cells and ¹²⁵I-labeled envelope glycoprotein, gp70, of the virus. The binding was competitively inhibited by extracts of ecotropic murine viruses. No inhibition was observed with a xenotropic or an amphotropic murine type-C virus, a murine type-B virus, and several nonmurine retroviruses. Unlike cells producing ecotropic murine viruses, murine cell lines actively producing either an endogenous xenotropic virus or an amphotropic virus showed a significant degree of receptor activity for Rauscher murine leukemia virus gp70. When murine cells were induced with iododeoxyuridine to produce a xenotropic virus and an ecotropic virus in distinct phases, the receptor activity of the induced cells remained unchanged during xenotropic virus release, but a dramatic decrease was evident with the onset of ecotropic virus release. These findings show that ecotropic murine viruses share a common receptor on the murine cell surface and that this receptor is distinct from those for xenotropic and amphotropic murine viruses.