The Packaging of Different Cargo into Enveloped Viral Nanoparticles

Abstract

Viral nanoparticles used for biomedical applications must be able to discriminate between tumor or virus-infected host cells and healthy host cells. In addition, viral nanoparticles must have the flexibility to incorporate a wide range of cargo, from inorganic metals to mRNAs to small molecules. Alphaviruses are a family of enveloped viruses for which some species are intrinsically capable of systemic tumor targeting. Alphavirus virus-like particles, or viral nanoparticles, can be generated from in vitro self-assembled core-like particles using nonviral nucleic acid. In this work, we expand on the types of cargo that can be incorporated into alphavirus core-like particles and the molecular requirements for packaging this cargo. We demonstrate that different core-like particle templates can be further enveloped to form viral nanoparticles that are capable of cell entry. We propose that alphaviruses can be selectively modified to create viral nanoparticles for biomedical applications and basic research.

Mechanisms of Virus Assembly

“…Specific RNA sequences or chemistry are not essential for assembly, as demonstrated by early in vitro experiments in which ssRNA capsid proteins assembled around heterologous nucleic acids and even polyvinylsulfate (72, 73), and more recent experiments in which capsid proteins assembled around various negatively charged substrates (e.g. (72–85)). We begin this section by describing what these experiments and theoretical models have revealed about how assembly depends on the physical characteristics of RNA or other polyelectrolytes, such as charge, size, and structure.…”

Self-Assembly of an Alphavirus Core-like Particle Is Distinguished by Strong Intersubunit Association Energy and Structural Defects

“…19–21, 23, 34 In vitro , alphavirus CP requires polyanionic cargo to form core-like particles (CLPs); the protein alone will not self-assemble in response to ionic strength or pH at any concentration yet tested. 16, 35–39 In vitro -assembled CLPs are structurally and functionally similar to cores of mature virions 14, 16 as they appear to have T=4 symmetry and are able to interact with viral glycoproteins 26, 40–42 to form functional virus-like particles. 41, 42 …”

Multi‐Component Self‐Assembly of Proteins and Inorganic Particles: From Discrete Structures to Biomimetic Materials

“…Viral containers have been successfully employed for the encapsulation of non-native cargo such as nanoparticles. [13] As discussed above, they were evolved to carry their construction plan encapsulated into the protein capsid. Therefore, the inner surface of these containers is mostly positively charged to facilitate RNA encapsulation.…”