1. ¹Got-A-Gene AB, Kullavik, Sweden
2. ²Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
3. ³Molecular Biotechnology, Royal Institute of Technology, Stockholm, Sweden

Correspondence: Dr MK Magnusson, Got-A-Gene AB, Östra Kyviksvägen 18, 429 30 Kullavik, Sweden. E-mail: maria.magnusson@gotagene.se

Received 1 July 2008; Revised 21 September 2008; Accepted 21 September 2008; Published online 23 October 2008.

Abstract

Vectors based on Adenovirus type 5 (Ad5) are among the most common vectors in cancer gene therapy trials to date. However, for increased efficiency and safety, Ad5 should be de-targeted from its native receptors and re-targeted to a tumor antigen. We have described earlier an Ad5 vector genetically re-targeted to the tumor antigen HER2/neu by a dimeric version of the Affibody molecule ZH inserted in the HI-loop of the fiber knob of a coxsackie and adenovirus receptor-binding ablated fiber. This virus showed almost wild-type growth characteristics and infected cells through HER2/neu. Here we generate vectors with double specificity by incorporating two different Affibody molecules, ZH (HER2/neu-binding) and ZT (Taq polymerase-binding), at different positions relative to one another in the HI-loop. Receptor-binding studies together with viral production and gene transfer assays showed that the recombinant fiber with ZT in the first position and ZH in the second position (ZTZH) bound to both its targets, whereas surprisingly, the fiber with ZHZT was devoid of binding to HER2/neu. Hence, it is possible to construct a recombinant adenovirus with dual specificity after evaluating the best position for each ligand in the fiber knob.