Energetic Changes Caused by Antigenic Module Insertion in a Virus-Like Particle Revealed by Experiment and Molecular Dynamics Simulations

Abstract

The success of recombinant virus-like particles (VLPs) for human papillomavirus and hepatitis B demonstrates the potential of VLPs as safe and efficacious vaccines. With new modular designs emerging, the effects of antigen module insertion on the self-assembly and structural integrity of VLPs should be clarified so as to better enabling improved design. Previous work has revealed insights into the molecular energetics of a VLP subunit, capsomere, comparing energetics within various solution conditions known to drive or inhibit self-assembly. In the present study, molecular dynamics (MD) simulations coupled with the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) method were performed to examine the molecular interactions and energetics in a modular capsomere of a murine polyomavirus (MPV) VLP designed to protect against influenza. Insertion of an influenza antigenic module is found to lower the binding energy within the capsomere, and a more active state is observed in Assembly Buffer as compared with that in Stabilization Buffer, which has been experimentally validated through measurements using differential scanning calorimetry. Further in-depth analysis based on free-energy decomposition indicates that destabilized binding can be attributed to electrostatic interaction induced by the chosen antigen module. These results provide molecular insights into the conformational stability of capsomeres and their abilities to be exploited for antigen presentation, and are expected to be beneficial for the biomolecular engineering of VLP vaccines.

Engineering virus-like particles as vaccine platforms

“…This is highlighted by recent efforts to add coiled-coil domains to P22 bacteriophage VLPs to aid in folding and display of large foreign antigens [20]. Rationally designing hybrid protein structures based on the building blocks found in nature will drive the field toward more stable and versatile VLP vaccine platforms and recent efforts to use computational modeling to predict whether peptides are compatible with VLP assembly may also improve success rates [42–46]. Synthetic multi-subunit structures that are modeled and engineered to be built from simple protein subunits are already being made [47,48], and as computational approaches for protein design improve, this holds promise for eventually generating new synthetic VLP platforms that are only tangentially based on viruses found in nature.…”

High-throughput process development of an alternative platform for the production of virus-like particles in Escherichia coli

“…A promising approach to the rapid and scalable production of VLPs is the expression of virus proteins in Escherichia coli. E. coli is the recombinant system of choice for multiple biopharmaceutical products, such as human insulin [8], human growth hormones [9], antibody fragments [10], or hepatitis vaccines [11], providing high product titers and total soluble protein values of up to 50% [12].…”

Design strategies to address the effect of hydrophobic epitope on stability and in vitro assembly of modular virus‐like particle

“…One possibility is the hydrophobic–hydrophobic interactions between surface exposed RV10 elements, driving the formation of aggregates. Poor capsomere and VLP stability can also arise due to module insertion, causing a reduction of stabilization energy . Thus, this necessitates specific design of RV10 modules that will maintain capsomeres stability in compatible VLP assembly buffer.…”