Phenotypic Mixing between Murine Oncoviruses and Murine Cytomegalovirus

Abstract

In vitro interactions between murine cytomegalovirus (MCMV) and murine leukemia viruses (MuLV), 2 groups of enveloped viruses capable of causing persistent or latent infections in vivo, were examined for evidence for phenotypic mixing. The growth of MCMV in murine [mouse] cells productively infected with ecotropic MuLV resulted regularly in the production of phenotypically mixed particles having the envelope antigens of MuLV and the genome of MCMV [MCMV(MuLV) pseudotypes]. The identity of such pseudotype particles was confirmed using specific anti-MuLV serum and by the demonstration of restriction due to viral interference of penetration of these particles on MuLV-infected murine cells. This restriction was independent of N- or B-tropism. The production of reverse pseudotypes could not be examined because of the lytic effects of MCMV on the requisite assay cells.