1. ¹Department of Gene Vectors, GSF-National Research Center for Environment and Health, Munich, Germany
2. ²Institute of Molecular Immunology, Munich, Germany
3. ³Institute of Clinical Molecular Biology and Tumor Genetics, Munich, Germany
4. ⁴Clinic I of Internal Medicine, University of Cologne, Cologne, Germany

Correspondence: Dr W Hammerschmidt, Department of Gene Vectors, GSF-National Research Center for Environment and Health, Haematologikum, Marchioninistr. 25, D-81377 Munich, Germany. E-mail: hammerschmidt@gsf.de

Received 5 April 2005; Revised 24 May 2005; Accepted 30 June 2005; Published online 1 September 2005.

Abstract

The efficient gene transfer of immunostimulatory cytokines into autologous tumor cells or the transfer of tumor-associated antigens into professional antigen-presenting cells is a prerequisite for many immunotherapeutic approaches. In particular with B cells, the efficiency of gene uptake is one of the limiting factors in cell-based vaccine strategies, since normal and malignant human B cells are commonly refractory to transducing gene vectors. Due to its natural tropism for human B cells, Epstein–Barr virus (EBV), a human herpes virus, might be an option, which we wanted to explore. EBV efficiently infects human B cells and establishes a latent infection, while the viral genome is maintained extrachromosomally. Although these characteristics are attractive, EBV is an oncogenic virus. Here, we present a novel EBV-derived vector, which lacks three EBV genes including two viral oncogenes and an essential lytic gene, and encodes granulocyte-macrophage colony-stimulating factor (GM-CSF) as a cytokine of therapeutic interest. We could show that EBV vectors efficiently transduce different B-cell lines, primary resting B cells, and tumor cells of B-cell lineage. Vector-derived GM-CSF was expressed in sufficient amounts to support the maturation of dendritic cells and their presentation of model antigens to cognate T-cell clones in autologous settings and an allogeneic, HLA-matched assay. We conclude that the EBV vector system might offer an option for ex vivo manipulation of B cells and gene therapy of B-cell lymphomas.