title: Intracellular trafficking of Gag and Env proteins and their interactions modulate pseudotyping of retroviruses.
abstract: Glycoproteins derived from most retroviruses and from several families of enveloped viruses can form infectious pseudotypes with murine leukemia virus (MLV) and lentiviral core particles, like the MLV envelope glycoproteins (Env) that are incorporated on either virus type. However, coexpression of a given glycoprotein with heterologous core proteins does not always give rise to highly infectious viral particles, and restrictions on pseudotype formation have been reported. To understand the mechanisms that control the recruitment of viral surface glycoproteins on lentiviral and retroviral cores, we exploited the fact that the feline endogenous retrovirus RD114 glycoprotein does not efficiently pseudotype lentiviral cores derived from simian immunodeficiency virus, whereas it is readily incorporated onto MLV particles. Our results indicate that recruitment of glycoproteins by the MLV and lentiviral core proteins occurs in intracellular compartments and not at the cell surface. We found that Env and core protein colocalization in intracytoplasmic vesicles is required for pseudotype formation. By investigating MLV/RD114 Env chimeras, we show that signals in the cytoplasmic tail of either glycoprotein differentially influenced their intracellular localization; that of MLV allows endosomal localization and hence recruitment by both lentiviral and MLV cores. Furthermore, we found that upon membrane binding, MLV core proteins could relocalize Env glycoproteins in late endosomes and allow their incorporation on viral particles. Thus, intracellular colocalization, as well as interactions between Env and core proteins, may influence the recruitment of the glycoprotein onto viral particles and generate infectious pseudotyped viruses.
authors.affiliation: Laboratoire de Vectorologie Rétrovirale et Thérapie Génique, INSERM U412, IFR128 BioSciences Lyon-Gerland, Ecole Normal Supérieure de Lyon, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Sandrin
authors.forename: Delphine
authors.initials: D
authors.lastname: Muriaux
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Darlix
authors.forename: François-Loïc
authors.initials: FL
authors.lastname: Cosset
mesh_terms: D000818:Animals; D019556:COS Cells; D002415:Cats; D002460:Cell Line; D020077:Endogenous Retroviruses / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D011992:Endosomes / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism*; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D009052:Leukemia Virus, Murine / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D018613:Microscopy, Confocal; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism; D014771:Virion / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D015686:Gene Products, env; D015683:Gene Products, gag; D011993:Recombinant Fusion Proteins