Formulation and evaluation of apolipoprotein B peptide-targeted siRNA liposomes against herpes simplex virus type 1: Delivery potential and limitations

Herpes simplex virus type 1 (HSV1) establishes lifelong latency in the trigeminal ganglia, and current antiviral treatments are unable to eliminate the latent virus or prevent reactivation. siRNA against HSV1 (siRNA@HSV1) silences HSV1 ICP0 gene, an immediate-early viral gene essential for HSV1 replication and reactivation. This study aimed to formulate siRNA@HSV1 loaded Apolipoprotein B (ApoB) peptide-targeted liposomes, leveraging ApoB's affinity for proteoglycans (PGs) and low-density lipoprotein receptors. Liposomes were prepared by the thin-film hydration technique following covalent binding of the ApoB peptide to DSPE-PEG lipid for targeting. The formulations were evaluated for physicochemical properties and stability using DLS, siRNA encapsulation by NanoDrop, cytotoxicity by MTT assay, extracellular matrix (ECM) binding by competition assay using Matrigel, and in vivo biodistribution in mice following retro-orbital and intraperitoneal (IP) administrations. The liposomes exhibited nanoscale size, narrow size distribution, neutral surface charge, efficient siRNA loading, and a uniform spherical morphology. ApoB peptide-targeted liposomes showed enhanced binding to the ECM in vitro, while biodistribution studies in mice showed preferential accumulation in the trigeminal ganglia following systemic IP administration. However, ApoB peptide-targeted liposomes encapsulating siRNA@HSV1 were poorly stable. Liposomes aggregated after 1 month of storage at 4^°C, and membrane labeling with various fluorescent probes resulted in rapid quenching. Consequently, antiviral studies were not performed. These findings suggest an incompatibility between siRNA@HSV1 and ApoB peptide. Overall, this study highlights the potential of ApoB peptide-targeted liposomes for trigeminal ganglia delivery but underscores the need for improved stability and/or alternative targeting strategies to advance siRNA-based therapies against latent HSV1.