title: The Engineering of a Novel Ligand in gH Confers to HSV an Expanded Tropism Independent of gD Activation by Its Receptors.
abstract: Herpes simplex virus (HSV) enters cells by means of four essential glycoproteins - gD, gH/gL, gB, activated in a cascade fashion by gD binding to one of its receptors, nectin1 and HVEM. We report that the engineering in gH of a heterologous ligand - a single-chain antibody (scFv) to the cancer-specific HER2 receptor - expands the HSV tropism to cells which express HER2 as the sole receptor. The significance of this finding is twofold. It impacts on our understanding of HSV entry mechanism and the design of retargeted oncolytic-HSVs. Specifically, entry of the recombinant viruses carrying the scFv-HER2-gH chimera into HER2+ cells occurred in the absence of gD receptors, or upon deletion of key residues in gD that constitute the nectin1/HVEM binding sites. In essence, the scFv in gH substituted for gD-mediated activation and rendered a functional gD non-essential for entry via HER2. The activation of the gH moiety in the chimera was carried out by the scFv in cis, not in trans as it occurs with wt-gD. With respect to the design of oncolytic-HSVs, previous retargeting strategies were based exclusively on insertion in gD of ligands to cancer-specific receptors. The current findings show that (i) gH accepts a heterologous ligand. The viruses retargeted via gH (ii) do not require the gD-dependent activation, and (iii) replicate and kill cells at high efficiency. Thus, gH represents an additional tool for the design of fully-virulent oncolytic-HSVs retargeted to cancer receptors and detargeted from gD receptors.
authors.affiliation: Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Gatta
authors.affiliation: Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Biljana
authors.initials: B
authors.lastname: Petrovic
authors.affiliation: Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Campadelli-Fiume
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002470:Cell Survival; D004274:DNA, Recombinant / Q000737:chemistry / Q000378:metabolism* / Q000627:therapeutic use; D015316:Genetic Therapy; D006801:Humans; D008024:Ligands; D009154:Mutation; D009369:Neoplasms / Q000378:metabolism / Q000628:therapy; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000627:therapeutic use; D015202:Protein Engineering; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use; D015398:Signal Transduction; D018139:Simplexvirus / Q000502:physiology*; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use; D056189:Viral Tropism; D053586:Virus Internalization
chemical_list: D004274:DNA, Recombinant; D008024:Ligands; D010446:Peptide Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D014759:Viral Envelope Proteins; C000606255:R-VG803; C000606256:R-VG809; C508053:ERBB2 protein, human