title: Insertion of targeting domains into the envelope glycoprotein of Moloney murine leukemia virus (MoMLV)-based vectors modulates the route of mCAT-1-mediated viral entry.
abstract: Several groups have inserted targeting domains into the envelope glycoprotein (Env) of Moloney murine leukemia virus (MoMLV) in an attempt to produce targeted retroviral vectors for human gene therapy. While binding of these modified Envs to the target molecule expressed on the surface of human cells was observed, specific high-titer infection of human cells expressing the target molecule was not achieved. Here we investigate the initial steps in the entry process of targeted MoMLV vectors both in murine and human cells expressing the MoMLV receptor, the mouse cationic amino acid transporter-1 (mCAT-1). We show that insertion of a small ligand targeted to E-selectin and of a single chain antibody (scFv) targeted to folate-binding protein (FBP) into the N-terminus of MoMLV Env results in the reduction of the infectivity and the kinetics of entry of the MoMLV vectors. The use of soluble receptor-binding domain (sRBD), bafilomycin A1 (BafA1) and methyl-beta-cyclodextrin (MbetaC) increase the infectivity of the MoMLV vectors targeted to FBP (MoMLV-FBP) suggesting that the scFv targeted to FBP increases the threshold for fusion and might re-route entry of the targeted MoMLV-FBP vector towards an endocytic, non-productive pathway.
authors.affiliation: Department of Medical Microbiology and Genitourinary Medicine, University of Liverpool, Liverpool, UK. aviejo@cnb.uam.es
authors.forename: A
authors.initials: A
authors.lastname: Viejo-Borbolla
authors.forename: M
authors.initials: M
authors.lastname: Pizzato
authors.forename: E D
authors.initials: ED
authors.lastname: Blair
authors.forename: T F
authors.initials: TF
authors.lastname: Schulz
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D027201:Cationic Amino Acid Transporter 1 / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D019040:E-Selectin / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D058973:Folate Receptors, GPI-Anchored; D015686:Gene Products, env / Q000235:genetics* / Q000502:physiology; D005822:Genetic Vectors; D006801:Humans; D008024:Ligands; D018942:Macrolides / Q000494:pharmacology; D051379:Mice; D008979:Moloney murine leukemia virus / Q000235:genetics* / Q000502:physiology; D011956:Receptors, Cell Surface / Q000378:metabolism; D011991:Receptors, Virus / Q000235:genetics / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics* / Q000502:physiology; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D027201:Cationic Amino Acid Transporter 1; D019040:E-Selectin; D004791:Enzyme Inhibitors; D058973:Folate Receptors, GPI-Anchored; D015686:Gene Products, env; D008024:Ligands; D018942:Macrolides; D011956:Receptors, Cell Surface; D011991:Receptors, Virus; C420826:Slc7a1 protein, mouse; D014764:Viral Proteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C090373:Env-Mlvi-4 protein, Moloney murine leukemia virus; C040929:bafilomycin A1