Viruses 2010, 2(10), 2290-2355; doi:10.3390/v2102290
Review

Tropism-Modification Strategies for Targeted Gene Delivery Using Adenoviral Vectors

1email, 1email, 1email, 1email, 2email, 1email and 1,* email
Received: 2 September 2010; Accepted: 7 October 2010 / Published: 13 October 2010
(This article belongs to the Special Issue Adenoviral Vectors)
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Abstract: Achieving high efficiency, targeted gene delivery with adenoviral vectors is a long-standing goal in the field of clinical gene therapy. To achieve this, platform vectors must combine efficient retargeting strategies with detargeting modifications to ablate native receptor binding (i.e. CAR/integrins/heparan sulfate proteoglycans) and “bridging” interactions. “Bridging” interactions refer to coagulation factor binding, namely coagulation factor X (FX), which bridges hepatocyte transduction in vivo through engagement with surface expressed heparan sulfate proteoglycans (HSPGs). These interactions can contribute to the off-target sequestration of Ad5 in the liver and its characteristic dose-limiting hepatotoxicity, thereby significantly limiting the in vivo targeting efficiency and clinical potential of Ad5-based therapeutics. To date, various approaches to retargeting adenoviruses (Ad) have been described. These include genetic modification strategies to incorporate peptide ligands (within fiber knob domain, fiber shaft, penton base, pIX or hexon), pseudotyping of capsid proteins to include whole fiber substitutions or fiber knob chimeras, pseudotyping with non-human Ad species or with capsid proteins derived from other viral families, hexon hypervariable region (HVR) substitutions and adapter-based conjugation/crosslinking of scFv, growth factors or monoclonal antibodies directed against surface-expressed target antigens. In order to maximize retargeting, strategies which permit detargeting from undesirable interactions between the Ad capsid and components of the circulatory system (e.g. coagulation factors, erythrocytes, pre-existing neutralizing antibodies), can be employed simultaneously. Detargeting can be achieved by genetic ablation of native receptor-binding determinants, ablation of “bridging interactions” such as those which occur between the hexon of Ad5 and coagulation factor X (FX), or alternatively, through the use of polymer-coated “stealth” vectors which avoid these interactions. Simultaneous retargeting and detargeting can be achieved by combining multiple genetic and/or chemical modifications.
Keywords: adenovirus; retargeting; detargeting; tropism; ligand; capsid protein
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Coughlan, L.; Alba, R.; Parker, A.L.; Bradshaw, A.C.; McNeish, I.A.; Nicklin, S.A.; Baker, A.H. Tropism-Modification Strategies for Targeted Gene Delivery Using Adenoviral Vectors. Viruses 2010, 2, 2290-2355.

AMA Style

Coughlan L, Alba R, Parker AL, Bradshaw AC, McNeish IA, Nicklin SA, Baker AH. Tropism-Modification Strategies for Targeted Gene Delivery Using Adenoviral Vectors. Viruses. 2010; 2(10):2290-2355.

Chicago/Turabian Style

Coughlan, Lynda; Alba, Raul; Parker, Alan L.; Bradshaw, Angela C.; McNeish, Iain A.; Nicklin, Stuart A.; Baker, Andrew H. 2010. "Tropism-Modification Strategies for Targeted Gene Delivery Using Adenoviral Vectors." Viruses 2, no. 10: 2290-2355.


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