Protein cargo encapsulation by virus‐like particles: Strategies and applications

Abstract

Viruses and the recombinant protein cages assembled from their structural proteins, known as virus-like particles (VLPs), have gained wide interest as tools in biotechnology and nanotechnology. Detailed structural information and their amenability to genetic and chemical modification make them attractive systems for further engineering. This review describes the range of nonenveloped viruses that have been co-opted for heterologous protein cargo encapsulation and the strategies that have been developed to drive encapsulation. Spherical capsids of a range of sizes have been used as platforms for protein cargo encapsulation. Various approaches, based on native and non-native interactions between the cargo proteins and inner surface of VLP capsids, have been devised to drive encapsulation. Here, we outline the evolution of these approaches, discussing their benefits and limitations. Like the viruses from which they are derived, VLPs are of interest in both biomedical and materials applications. The encapsulation of protein cargo inside VLPs leads to numerous uses in both fundamental and applied biocatalysis and biomedicine, some of which are discussed herein. The applied science of protein-encapsulating VLPs is emerging as a research field with great potential. Developments in loading control, higher order assembly, and capsid optimization are poised to realize this potential in the near future.

Tunable In Vivo Colocalization of Enzymes within P22 Capsid-Based Nanoreactors

“…Furthermore, a variety of strategies have been established for the in vivo and in vitro encapsulation of protein cargos. 8 Encapsulation of protein cargos within VLPs has been shown to confer stabilization against proteases, high temperatures, and chemical denaturants. 3,9,10 Additionally, sequestration within VLPs can prevent misfolding and aggregation of recombinant proteins.…”

“…They self-assemble into uniform structures, are biocompatible, generally porous to small molecules, and amenable to genetic and chemical modification. Furthermore, a variety of strategies have been established for the in vivo and in vitro encapsulation of protein cargos …”

Highly modular hepatitis B virus-like nanocarriers for therapeutic protein encapsulation and targeted delivery to triple negative breast cancer cells

“…This is most likely due to steric effects of encapsulating a large number of protein cargoes simultaneously, which prevents efficient assembly of complete capsid structures. 45,71…”

“…This is most likely due to steric effects of encapsulating a large number of protein cargoes simultaneously, which prevents efficient assembly of complete capsid structures. 45,71 To address the steric constraints of cargo encapsulation, we developed a multi-expression strategy to facilitate interior loading of multiple protein cargos based on co-assembly of both unmodified HBV monomers and modified HBV monomers fused with a cargo protein at the C-terminus. To implement this approach, we began with a dual-expression system to encapsulate GFP inside the HBV SpyTag VLP.…”

Electrostatic Theory of the Acidity of the Solution in the Lumina of Viruses and Virus-Like Particles

“…17,18 Because virus coat proteins are able to encapsulate molecular cargo, either spontaneously from solution or by attaching it chemically or physically to, e.g., the RNA binding domain of the protein, there is a significant interest in utilising this property for application purposes in targeted drug delivery, tomography, controlled catalysis and metamaterials. [19][20][21][22] Recently, virus-based artificial organelles have been suggested as a viable route to be used in living cells for therapeutic purposes, restoring or even adding cellular activity. 23 These artificial organelles contain catalytically active particles such as enzymes.…”