Short interfering ribonucleic acids (siRNAs) have garnered interest for their potency and specificity in treating diseases caused by gene dysregulation, with increasing numbers ofoligonucleotide-based therapies entering clinical trials. Nevertheless, delivery challenges such as serum stability and targeting prevent siRNAs from being fully utilized in many applications, resulting in few FDA-approved siRNA therapies. To address these challenges, siRNAs are commonly encapsulated in non-viral nanocarriers, which offer high loading capacity and design flexibility by leveraging advances in chemical synthesis. However, difficulties in controlling particle size, polydispersity, and siRNA release often cause rapid hepatic clearance or inefficient siRNA utilization and have hindered further advancement of many siRNA formulations.<br/><br/>In nature, viruses have developed efficient features to mediate infection, with regular, multifunctional architectures and ideal sizes that enable evasion of the mononuclear phagocytic system. Inspired by these viral analogues, many efforts have focused on developing virus-like particles (VLPs) as non-infectious capsids with drug delivery potential based on their shared structural features. The well-characterized hepatitis B virus (HBV) VLP is an ideal siRNA delivery vehicle because it has regular, solvent exposed features for incorporating surface modifications, a large interior cavity amenable for loading cargoes, and a suitable size for favorable pharmacokinetics. In our work, a VLP delivery system with increased targeting potential was established by incorporating the SpyCatcher-SpyTag protein-peptide pair into the HBV capsid monomer to facilitate modular site- and orientation-specific nanocarrier modification. SpyTag is genetically inserted into the HBV capsid, while SpyCatcher is fused to potential delivery moieties, such as purification tags and targeting ligands. Simultaneously, genetic fusion of the siRNA binding protein p19 on the capsid interior can facilitate siRNA loading. Currently, we have successfully assembled the SpyTagged HBV capsid with p19 incorporation and have demonstrated SpyTag functionality by ligating elastin-like polypeptide purification tags for a temperature driven, scalable purification method. Future work will incorporate targeting and endosomolytic peptides for targeted siRNA delivery to inflammatory breast cancer cells, a highly invasive breast cancer subtype, to enable analysis of targeted gene silencing<i>.</i>

Targeted siRNA delivery with modular hepatitis B virus-like particles

2019 Spring National Meeting

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