Small Molecules Engineered to Trigger Virus-like Particle Disassembly

Abstract A molecular delivery system needs to release, as well as package, cargo. In previous work, technology has been described for packaging cargo into virus-like particles (VLPs) based on the Hepatitis B Virus capsid. Here, we describe a panel of dansyl maleimides (DM) designed to trigger VLP disassembly in response to a reducing environment. The VLP is stabilized by protein–protein interactions and also disulfide cross-links between the C-terminal cysteine of each capsid protein (Cp). The DM molecules react with a second cysteine, buried at the Cp-Cp interface. The DMs, of varying size, disrupt Cp-Cp interactions, leaving VLPs held together primarily by disulfide cross-links. Introduction of β-mercaptoethanol (βME), emulating the reducing environment of the cytoplasm, results in the disassembly of the DM-labeled VLPs. The most effective DM binds VLPs slowly, destabilizes them more than other DMs, and leads to rapid disassembly; with this DM, labeling as few as 50% of available sites led to disassembly. Cargo-loaded DM-labeled VLPs also showed complete disassembly when incubated with βME. This work outlines a strategy for future development of VLPs as nanocontainers that are responsive to the environment.