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Journal of Virology, March 2001, p. 2972-2981, Vol. 75, No. 6
Genetic Therapy, Inc./A Novartis Company,
Gaithersburg, Maryland 20878,1 and
Department of Immunology, The Scripps Research Institute,
La Jolla, California 920372
Received 3 October 2000/Accepted 20 November 2000
A major limitation of adenovirus type 5 (Ad5)-based gene therapy,
the inability to target therapeutic genes to selected cell types, is
attributable to the natural tropism of the virus for the widely
expressed coxsackievirus-adenovirus receptor (CAR) protein.
Modifications of the Ad5 fiber knob domain have been shown to alter the
tropism of the virus. We have developed a novel system to rapidly
evaluate the function of modified fiber proteins in their most
relevant context, the adenoviral capsid. This transient transfection/infection system combines transfection of cells with plasmids that express high levels of the modified fiber protein and
infection with Ad5.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.6.2972-2981.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Adenovirus Type 5 Viral Particles Pseudotyped with
Mutagenized Fiber Proteins Show Diminished Infectivity of
Coxsackie B-Adenovirus Receptor-Bearing Cells
gal.
F, an E1-, E3-, and fiber-deleted adenoviral vector encoding
-galactosidase. We have used this system
to test the adenoviral transduction efficiency mediated by a panel of
fiber protein mutants that were proposed to influence CAR interaction.
A series of amino acid modifications were incorporated via mutagenesis
into the fiber expression plasmid, and the resulting fiber proteins
were subsequently incorporated onto adenoviral particles. Mutations
located in the fiber knob AB and CD loops demonstrated the greatest
reduction in fiber-mediated gene transfer in HeLa cells. We also
observed effects on transduction efficiency with mutations in the FG
loop, indicating that the binding site may extend to the adjacent
monomer in the fiber trimer and in the HI loop. These studies support
the concept that modification of the fiber knob domain to diminish or
ablate CAR interaction should result in a detargeted adenoviral vector
that can be combined simultaneously with novel ligands for the
development of a systemically administered, targeted adenoviral vector.
*
Corresponding author. Mailing address: Genetic Therapy,
Inc./A Novartis Company, 9 West Watkins Mill Rd., Gaithersburg,
MD 20878. Phone: (301) 258-4830. Fax: (301) 258-4680. E-mail: sue.stevenson{at}pharma.novartis.com.
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