1. ¹Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
2. ²Institute of Virology, Philipps University of Marburg, Marburg, Germany
3. ³Division of Paediatric Haematology and Oncology, University Hospital, Frankfurt, Germany
4. ⁴Division of Applied Virology and Gene Therapy, Georg-Speyer-Haus, Institute for Biomedical Research, Frankfurt, Germany
5. ⁵Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA

Correspondence: Christian J. Buchholz, Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Str. 51-53, 63225 Langen, Germany. E-mail: bucch@pei.de

Received 17 January 2008; Accepted 15 May 2008; Published online 24 June 2008.

Abstract

Retargeting of lentiviral vector entry to cell types of interest is a key factor in improving the safety and efficacy of gene transfer. In this study we show that the retargetable envelope glycoproteins of measles virus (MV), namely, the hemagglutinin (H) responsible for receptor recognition and the fusion protein (F), can pseudotype human immunodeficiency virus 1 (HIV-1) vectors when their cytoplasmic tails are truncated. We then pseudotyped HIV-1 vectors with MV glycoproteins displaying on H either the epidermal growth factor or a single-chain antibody directed against CD20, but without the ability to recognize their native receptors. Gene transfer into cells that expressed the targeted receptor was several orders of magnitude more efficient than into cells that did not. High-target versus nontarget cell discrimination was demonstrated in mixed cell populations, where the targeting vector selectively eliminated CD20-positive cells after suicide gene transfer. Remarkably, primary human CD20-positive B lymphocytes were transduced more efficiently by the CD20-targeted vector than by a vector pseudotyped with the vesicular stomatitis virus G (VSV-G) protein. In addition, the CD20-targeted vector was able to transduce even unstimulated primary B cells, whereas VSV-G pseudotyped vectors were unable to do so. Because MV enters cells through direct fusion at the cell membrane, this novel targeting system should be widely applicable.