Volume 131, Issue 5 pp. E659-E669
Tumor Immunology

Preventing vaccinia virus class-I epitopes presentation by HSV-ICP47 enhances the immunogenicity of a TAP-independent cancer vaccine epitope

Nermin Raafat

Nermin Raafat

Department of Biomedicine, Oncology group, Institute of Surgical Research and Hospital Management, University of Basel, Switzerland

Department of Biochemistry and Molecular Biology, Faculty of Medicine, Zagazig University, Zagazig, Egypt

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Charlotte Sadowski-Cron

Charlotte Sadowski-Cron

Department of Thoracic Surgery, University Hospital of Basel, Switzerland

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Chantal Mengus

Chantal Mengus

Department of Biomedicine, Oncology group, Institute of Surgical Research and Hospital Management, University of Basel, Switzerland

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Michael Heberer

Michael Heberer

Department of Biomedicine, Oncology group, Institute of Surgical Research and Hospital Management, University of Basel, Switzerland

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Giulio C. Spagnoli

Giulio C. Spagnoli

Department of Biomedicine, Oncology group, Institute of Surgical Research and Hospital Management, University of Basel, Switzerland

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Paul Zajac

Corresponding Author

Paul Zajac

Department of Biomedicine, Oncology group, Institute of Surgical Research and Hospital Management, University of Basel, Switzerland

Tel.: 0041-0-61-265-2330, Fax: 0041-0-61-265-3990

ICFS, laboratory 404, Hebelstrasse, 20, CH-4031, Basel, SwitzerlandSearch for more papers by this author
First published: 24 November 2011
Citations: 18

Abstract

Herpes simplex virus protein ICP47, encoded by US12 gene, strongly downregulates major histocompatibility complex (MHC) class-I antigen restricted presentation by blocking transporter associated with antigen processing (TAP) protein. To decrease viral vector antigenic immunodominance and MHC class-I driven clearance, we engineered recombinant vaccinia viruses (rVV) expressing ICP47 alone (rVV-US12) or together with endoplasmic reticulum (ER)-targeted Melan-A/MART-127–35 model tumor epitope (rVV-MUS12). In this study, we show that antigen presenting cells (APC), infected with rVV-US12, display a decreased ability to present TAP dependent MHC class-I restricted viral antigens to CD8+ T-cells. While HLA class-I cell surface expression is strongly downregulated, other important immune related molecules such as CD80, CD44 and, most importantly, MHC class-II are unaffected. Characterization of rVV-MUS12 infected cells demonstrates that over-expression of a TAP-independent peptide, partially compensates for ICP47 induced surface MHC class-I downregulation (30% vs. 70% respectively). Most importantly, in conditions where clearance of infected APC by virus-specific CTL represents a limiting factor, a significant enhancement of CTL responses to the tumor epitope can be detected in cultures stimulated with rVV-MUS12, as compared to those stimulated by rVV-MART alone. Such reagents could become of high relevance in multiple boost protocols required for cancer immunotherapy, to limit vector-specific responsiveness.

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