Site‐Specific Modification of Adeno‐Associated Viruses via a Genetically Engineered Aldehyde Tag

Abstract

As a consequence of their well-defined nanostructure and intrinsic bioactive functionality, virus-based nanoparticles have shown promise for mediating gene delivery. Adeno-associated virus (AAV) nanoparticles, which possess an excellent safety profile and therapeutic potential, hold potential for use in human gene therapy. However, because of their native tropisms, the applicability of AAV nanoparticles is often limited to restricted ranges of cells or tissues. Thus, retargeting AAV particles to the desired cell populations has continued to be a major research focus in many gene therapy applications. In this study, a general strategy is reported for nanoparticle targeting. This involves the site-specific modification of AAV type 2 (AAV2) by genetically incorporating a short peptide, in this case an aldehyde tag, in the viral capsid. Such a tag can be exploited for site-specific attachment of targeting molecules and allows for further introduction of targeting antibodies or ligands. It is shown that this modification neither affects the level of infectious viral titer nor intracellular trafficking properties. Furthermore, the site-specific conjugation of targeting antibodies could significantly enhance viral transduction to those target cells that have otherwise exhibited very low permissiveness to AAV2 infection. This method also allows the functional incorporation of RGD peptides onto AAV2 for enhanced delivery with implications for cancer gene therapy.

Reversible PEGylation and Schiff-base linked imidazole modification of polylysine for high-performance gene delivery

“…[4][5][6][7][8] While viral vectors, such as adenoviruses and retroviruses can mediate highly efficient gene transfer, they pose safety issues such as healthy cell inection, inammation, immunogenicity, carcinogenicity, and the possibility of gene recombination, which prompted parallel pursuit for non-viral vectors. 1-3 Successful gene therapies, however, strongly depend on the development of effective and safe gene delivery vectors that are capable of mediating high and sustained levels of gene expression.…”

Engineering the AAV capsid to optimize vector–host-interactions

“…Specifically, a cysteine-containing peptide sequence that is modified by a cellular enzyme to an aldehyde was introduced into the AAV2 capsid protein sequences. Through this reactive group ligands equipped with a hydrazide or hydroxylamine are covalently linked thus introducing a modification that cannot dissociate [34]. Another interesting variation of the targeting concept relies on the idea to use a chemical switch, thereby limiting target receptor binding to a specific predefined condition [35].…”

Synthetic virology: engineering viruses for gene delivery

“…59 Similarly, genetic insertion of a small peptide sequence recognized by cellular formylglycine generating enzyme can lead to display of aldehyde groups, which can mediate site-selective conjugation of hydrazide-functionalized motifs to virus capsids. 60 …”