1. ¹VectorLogics, Inc., Birmingham, AL, USA
2. ²ESBATech AG, Zurich-Schlieren, Switzerland
3. ³Division of Human Gene Therapy, Departments of Medicine, Pathology, and Surgery, and the Gene Therapy Center at the University of Alabama at Birmingham, Birmingham, AL, USA

Correspondence: Dr DT Curiel, Division of Human Gene Therapy, 901 19th Street South, BMR2 502, Birmingham, AL 35294, USA. E-mail: curiel@uab.edu

⁴Both these authors are equity holders in VectorLogics Inc.

Received 20 April 2005; Revised 21 June 2005; Accepted 7 July 2005; Published online 18 August 2005.

Abstract

Adenovirus (Ad) vectors are of utility for many therapeutic applications. Strategies have been developed to alter adenoviral tropism to achieve a cell-specific gene delivery capacity employing fiber modifications allowing genetic incorporation of targeting motifs. In this regard, single chain antibodies (scFv) represent potentially useful agents to achieve targeted gene transfer. However, the distinct biosynthetic pathways that scFv and Ad capsid proteins are normally routed through have thus far been problematic with respect to scFv incorporation into the Ad capsid. Utilization of stable scFv, which also maintain correct folding and thus functionality under intracellular reducing conditions, could overcome this restriction. We genetically incorporated a stable scFv into a de-knobbed, fibritin-foldon trimerized Ad fiber and demonstrated selective targeting to the cognate epitope expressed on the membrane surface of cells. We have shown that the scFv employed in this study retains functionality and that stabilizing the targeting molecule, per se, is critical to allow retention of antigen recognition in the adenovirus capsid-incorporated context.