title: Novel Chemokine-Based Immunotoxins for Potent and Selective Targeting of Cytomegalovirus Infected Cells.
abstract: Immunotoxins as antiviral therapeutics are largely unexplored but have promising prospective due to their high selectivity potential and their unparalleled efficiency. One recent example targeted the virus-encoded G protein-coupled receptor US28 as a strategy for specific and efficient treatment of human cytomegalovirus (HCMV) infections. US28 is expressed on virus-infected cells and scavenge chemokines by rapid internalization. The chemokine-based fusion-toxin protein (FTP) consisted of a variant (F49A) of CX3CL1 specifically targeting US28 linked to the catalytic domain ofPseudomonas exotoxinA (PE). Here, we systematically seek to improve F49A-FTP by modifications in its three structural domains; we generated variants with (1) altered chemokine sequence (K14A, F49L, and F49E), (2) shortened and elongated linker region, and (3) modified toxin domain. Only F49L-FTP displayed higher selectivity in its binding to US28 versus CX3CR1, the endogenous receptor for CX3CL1, but this was not matched by a more selective killing of US28-expressing cells. A longer linker and different toxin variants decreased US28 affinity and selective killing. Thereby, F49A-FTP represents the best candidate for HCMV treatment. Many viruses encode internalizing receptors suggesting that not only HCMV but also, for instance, Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus may be targeted by FTPs.
authors.affiliation: INAGEN Aps., Kongens Lyngby, Denmark; Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Katja
authors.initials: K
authors.lastname: Spiess
authors.affiliation: INAGEN Aps., Kongens Lyngby, Denmark.
authors.forename: Mads G
authors.initials: MG
authors.lastname: Jeppesen
authors.affiliation: INAGEN Aps., Kongens Lyngby, Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Malmgaard-Clausen
authors.affiliation: INAGEN Aps., Kongens Lyngby, Denmark.
authors.forename: Karen
authors.initials: K
authors.lastname: Krzywkowski
authors.affiliation: INAGEN Aps., Kongens Lyngby, Denmark; Section for Life Science and Bioengineering Innovation, Veterinary Institute, The Danish Technical University, Kongens Lyngby, Denmark.
authors.forename: Thomas N
authors.identifier: 0000-0001-6692-9435
authors.initials: TN
authors.lastname: Kledal
authors.affiliation: Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mette M
authors.identifier: 0000-0001-9600-3254
authors.initials: MM
authors.lastname: Rosenkilde
mesh_terms: D000998:Antiviral Agents / Q000009:adverse effects / Q000276:immunology* / Q000627:therapeutic use*; D001426:Bacterial Proteins / Q000276:immunology; D002478:Cells, Cultured; D054428:Chemokine CX3CL1 / Q000378:metabolism / Q000627:therapeutic use; D003587:Cytomegalovirus / Q000276:immunology*; D005347:Fibroblasts; D004854:Herpesvirus 4, Human; D006801:Humans; D000922:Immunotoxins / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000998:Antiviral Agents; D001426:Bacterial Proteins; C515538:CX3CL1 protein, human; D054428:Chemokine CX3CL1; D000922:Immunotoxins; C105181:ORF74 protein, Human herpesvirus 8; D019707:Receptors, Chemokine; C411191:US28 receptor, Cytomegalovirus; D014764:Viral Proteins; C111749:pseudomonas exoprotein A protein, Pseudomonas aeruginosa