SELECTIVE TARGETING OF HUMAN-CELLS BY A CHIMERIC ADENOVIRUS VECTOR CONTAINING A MODIFIED FIBER PROTEIN

The adenovirus fiber protein is responsible for attachment of the viri on to unidentified cell surface receptors. There are at least two dist inct adenovirus fiber receptors which interact with the group B (Ad3) and group C (Ad5) adenoviruses. We have previously shown by using expr essed adenovirus fiber proteins that it is possible to change the spec ificity of the fiber protein by exchanging the head domain with anothe r serotype which recognizes a different receptor (S. C. Stevenson et a l., J. Virol. 69:2850-2857, 1995). A chimeric fiber cDNA containing th e Ad3 fiber head domain fused to the Ad5 fiber tail and shaft was inco rporated into the genome of an adenovirus vector with E1 and E3 delete d encoding beta-galactosidase to generate Av9LacZ4, an adenovirus part icle which contains a chimeric fiber protein. Western blot analysis of the chimeric fiber vector confirmed expression of the chimeric fiber protein and its association with the adenovirus capsid. Transduction e xperiments with fiber protein competitors demonstrated the altered rec eptor tropism of the chimeric fiber vector compared to that of the par ental Av1LacZ4 vector. Transduction of a panel of human cell lines wit h the chimeric and parental vectors provided evidence for a different cellular distribution of the Ad5 and Ad3 receptors. Three cell lines ( THP-1, MRC-5, and FaDu) were more efficiently transduced by the vector containing the Ad3 fiber head than by the Ad5 fiber vector. In contra st, human coronary artery endothelial cells were transduced more readi ly with the vector containing the Ad5 fiber than with the chimeric fib er vector. HeLa and human umbilical vein endothelial cells were transd uced at equivalent levels compared with human diploid fibroblasts, whi ch were refractory to transduction with both vectors. These results pr ovide evidence for the differential expression of the Ad5 and Ad3 rece ptors on human cell lines derived from clinically relevant target tiss ues. Furthermore, we show that exchange of the fiber head domain is a viable approach to the production of adenovirus vectors with cell-type -selective transduction properties. It may be possible to extend this approach to the use of ligands for a range of different cellular recep tors in order to target gene transfer to specific cell types at the le vel of transduction.