Insertion of a ligand to HER2 in gB retargets HSV tropism and obviates the need for activation of the other entry glycoproteins

• Published in: PLoS pathogens 2017-04, Vol.13 (4), p.e1006352-e1006352
• Main Authors: Petrovic, Biljana, Gianni, Tatiana, Gatta, Valentina, Campadelli-Fiume, Gabriella
• Format: Article
• Language: English
• Subjects: Activation analysis; Antibodies; Apoptosis; Assaying; Attenuation; Binding; Biology and Life Sciences; Bypasses; Cancer; Carcinogenesis; Carcinogens; Carcinoma; Cell activation; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell fusion; Cell surface; Chains; Data acquisition; Data collection; Data processing; Decision analysis; Deoxyribonucleic acid; Depletion; Diagnostic systems; DNA; DNA vaccines; Endocytosis; Epidermal growth factor; Epidermal growth factors; Epithelial cells; ErbB-2 protein; Funding; Gene fusion; Gene mapping; Genetic aspects; Genetics; Glycoproteins; Glycoproteins - genetics; Glycoproteins - metabolism; Heparan sulfate; Herpes Simplex - pathology; Herpes Simplex - virology; Herpes simplex virus; Herpes viruses; Herpesvirus 1, Human - genetics; Herpesvirus 1, Human - pathogenicity; Herpesvirus 1, Human - physiology; Humans; Immunoglobulins; In vivo methods and tests; Infections; Insertion; Integrins; Integrins - genetics; Integrins - metabolism; Isoforms; Leukemia; Ligands; Lymphocytes T; Macrolides - pharmacology; Medical research; Medicine; Medicine and Health Sciences; Mice; Myelin; Nectins; Protein structure; Rafts; Receptor, ErbB-2 - genetics; Receptor, ErbB-2 - metabolism; Receptors, Tumor Necrosis Factor, Member 14 - genetics; Receptors, Tumor Necrosis Factor, Member 14 - metabolism; Receptors, Virus - genetics; Receptors, Virus - metabolism; Recombinant Fusion Proteins; Single-Chain Antibodies - genetics; Single-Chain Antibodies - metabolism; Social behavior; Studies; Tropism; Viral Tropism; Virology; Virus Internalization; Viruses
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1006352

Herpes simplex virus (HSV) entry into the cells requires glycoproteins gD, gH/gL and gB, activated in a cascade fashion by conformational modifications induced by cognate receptors and intermolecular signaling. The receptors are nectin1 and HVEM (Herpes virus entry mediator) for gD, and αvβ6 or αvβ8 integrin for gH. In earlier work, insertion of a single chain antibody (scFv) to the cancer receptor HER2 (human epidermal growth factor receptor 2) in gD, or in gH, resulted in HSVs specifically retargeted to the HER2-positive cancer cells, hence in highly specific non-attenuated oncolytic agents. Here, the scFv to HER2 was inserted in gB (gBHER2). The insertion re-targeted the virus tropism to the HER2-positive cancer cells. This was unexpected since gB is known to be a fusogenic glycoprotein, not a tropism determinant. The gB-retargeted recombinant offered the possibility to investigate how HER2 mediated entry. In contrast to wt-gB, the activation of the chimeric gBHER2 did not require the activation of the gD and of gH/gL by their respective receptors. Furthermore, a soluble form of HER2 could replace the membrane-bound HER2 in mediating virus entry, hinting that HER2 acted by inducing conformational changes to the chimeric gB. This study shows that (i) gB can be modified and become the major determinant of HSV tropism; (ii) the chimeric gBHER2 bypasses the requirement for receptor-mediated activation of other essential entry glycoproteins.