Recombinant Herpes Simplex Virus Type 1 Engineered for Targeted Binding to Erythropoietin Receptor-Bearing Cells

Abstract

The utility of recombinant herpes simplex virus type 1 (HSV-1) vectors may be expanded by manipulation of the virus envelope to achieve cell-specific gene delivery. To this end, an HSV-1 mutant virus deleted for glycoprotein C (gC) and the heparan sulfate binding domain of gB (KgBpK−gC−) was engineered to encode different chimeric proteins composed of N-terminally truncated forms of gC and the full-length erythropoietin hormone (EPO). Biochemical analyses demonstrated that one gC-EPO chimeric molecule (gCEPO2) was posttranslationally processed, incorporated into recombinant HSV-1 virus (KgBpK−gCEPO2), and neutralized with antibodies directed against gC or EPO in a complement-dependent manner. Moreover, KgBpK−gCEPO2 recombinant virus was specifically retained on a soluble EPO receptor column, was neutralized by soluble EPO receptor, and stimulated proliferation of FD-EPO cells, an EPO growth-dependent cell line. FD-EPO cells were nevertheless refractory to productive infection by both wild-type HSV-1 and recombinant KgBpK−gCEPO2 virus. Transmission electron microscopy of FD-EPO cells infected with KgBpK−gCEPO2 showed virus endocytosis leading to aborted infection. Despite the lack of productive infection, these data provide the first evidence of targeted HSV-1 binding to a non-HSV-1 cell surface receptor.

Bispecific Adapter-Mediated Retargeting of a Receptor-Restricted HSV-1 Vector to CEA-Bearing Tumor Cells

“…33,34 Depending on the administration route, it is likely that retargeting or detargeting of the attachment functions of gB and gC will be advantageous for virus retargeting in vivo. Both have been accomplished by relatively simple genetic modifications [35][36][37] and attachment-detargeted gB and gC can be used to build a standard detargeted vector as a component of a flexible, adapterdependent system for cell-specific virus infection. Although the role of gB binding to specific cellular receptors remains to be fully defined, 38 detargeting of gD from its multiple receptors is essential.…”

Enhanced nigrostriatal neuron-specific, long-term expression by using neural-specific promoters in combination with targeted gene transfer by modified helper virus-free HSV-1 vector particles

“…Targeted gene transfer with HSV-1 vectors was achieved by modifying gC to remove the heparin binding domain, and addition a binding site for a specific cell surface protein to either gC or gD. The initial study [ 16 ] reported a recombinant virus containing a chimeric gC – erythropoietin (EPO) that supported enhanced binding to cells that contained EPO receptors. Analogous designs used gD – IL13, or gD – urokinase plaminogen activator, or gD – single-chain anti-EGF receptor antibody chimeric proteins to target infection to tumor cells containing the cognate receptor [ 17 - 19 ].…”

Single-Step Conversion of Cells to Retrovirus Vector Producers with Herpes Simplex Virus–Epstein-Barr Virus Hybrid Amplicons

“…Since manipulation of these levels in vivo is not an option, optimization can only be accomplished by modifying the virions to increase the variety of cell surface receptors which can be used to enter cells. For HSV virions this could be achieved by using helper functions from different strains of HSV and/or modifying the virion envelope to enhance binding of the vector to receptors abundant on the target cells (37). For retrovirus vectors, a broader host range can be achieved by pseudotyping the virions with vesicular stomatitis virus envelope glycoprotein (5).…”