1. ¹Department of Clinical Pharmacology, University of Oxford, Oxford, UK
2. ²CR UK Institute for Cancer Studies, University of Birmingham, Birmingham, UK
3. ³Hybrid Systems Ltd, Cherwell Innovation Centre, Oxfordshire, UK
4. ⁴Tissue Repair Company, San Diego, CA, USA
5. ⁵Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, Prague 6, The Czech Republic
6. ⁶Department of Cell Biology and Immunology, Vrije Universiteit, Amsterdam, Netherlands

Correspondence: Dr M Stevenson, Department of Clinical Pharmacology, University of Oxford, Woodstock Road, Oxford OX2 6HE, UK. E-mail: mark.stevenson@clinpharm.ox.ac.uk

Received 7 September 2004; Revised 16 August 2005; Accepted 18 August 2005; Published online 15 December 2005.

Abstract

Non-human adenovirus vectors have attractive immunological properties for gene therapy but are frequently restricted by inefficient transduction of human target cells. Using chicken embryo lethal orphan (CELO) virus, we employed a nongenetic mechanism of polymer coating and retargeting with basic fibroblast growth factor (bFGF-pc-CELOluc), a strategy that permits efficient tropism modification of human adenovirus. bFGF-pc-CELOluc showed efficient uptake and transgene expression in chick embryo fibroblasts (CEF), and increased levels of binding and internalization in a variety of human cell lines. Transgene expression was also greater than unmodified CELOluc in PC-3 human prostate cells, although the specific activity (RLU per internalized viral genome) was decreased. In CEF, the specific activity of bFGF-pc-CELOluc was considerably higher than in the human prostate cell line PC-3. Retargeted virus was fully resistant to inhibition by human serum with known adenovirus-neutralizing activity in vitro, while in mice CELOluc was cleared less rapidly from the blood than Adluc following i.v. administration in the presence of adenovirus neutralizing serum. Polymer coating and retargeting with bFGF further reduced rates of clearance for both viruses, suggesting protection against both neutralizing and opsonizing factors. The data indicate that CELO virus may be retargeted to infect human cells via alternative, potentially disease-specific, receptors and resist the effects of pre-existing humoral immunity.