Coating of adeno‐associated virus with reactive polymers can ablate virus tropism, enable retargeting and provide resistance to neutralising antisera

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Abstract
Background Copolymers based on poly‐[N‐(2‐hydroxypropyl) methacrylamide] (HPMA) have been used previously to enable targeted delivery of adenovirus. Here we demonstrate polymer‐coating techniques can also be used to modify and retarget adeno‐associated virus (AAV) types 5 and 8. Methods Three strategies for modifying transductional targeting of AAV were employed. The first involved direct reaction of AAV5 or AAV8 with amino‐reactive HPMA copolymer. The second approach used carbodiimide (EDC) chemistry to increase the number of surface amino groups on the AAV5 capsid, thereby improving coating efficiency. In the third approach, the AAV5 genome was isolated from capsid proteins and delivered in a synthetic polyplex consisting of polyethylenimine (PEI) and HPMA. Results Efficient covalent attachment of HPMA copolymer to AAV5 could only be achieved following modification of the virus with EDC. Coating inhibited sialic acid dependent infection and provided a platform for retargeting via new ligands, including basic fibroblast growth factor. Retargeted infection was shown to be partially resistant to neutralising antisera. Delivery of AAV5 genomes using PEI and HPMA was efficient and provided absolute control of tropism and protection from antisera. In contrast AAV8 could be reacted directly with HPMA copolymer and allowed specific retargeting via the epidermal growth factor receptor, but gave no protection against neutralising antisera. Conclusions Reactive HPMA polymers can be used to ablate the natural tropism of both AAV8 and EDC‐modified AAV5 and enable receptor‐specific infection by incorporation of targeting ligands. These data show transductional targeting strategies can be used to improve the versatility of AAV vectors. Copyright © 2008 John Wiley & Sons, Ltd.