# Multimode Observation of Virus Capsid Assembly

> **NIH NIH R01** · TRUSTEES OF INDIANA UNIVERSITY · 2024 · $493,431

## Abstract

Summary
The capsid of the Hepatitis B Virus (HBV) is a 120-homodimer T=4 icosahedron. In vivo, it self-assembles,
packages viral RNA, serves as a metabolic compartment for DNA synthesis, and trafficks within the cell.
Its assembly and disassembly have become targets for potent antivirals. In the previous funding period,
we characterized assembly and disassembly with purified protein using structural, single molecule, and
bulk studies of assembly products and reactions. We characterized the allosteric transitions that activated
assembly, demonstrated the importance of reversibility during self-association for fidelity, and identified
roles of nucleation for directing the assembly path.
In this proposal, we develop hypotheses to take advantage of these results to engineer virus-like particles
with programmable assembly, cargo packaging, delivery, and release. In preliminary studies, we
developed a method for targeting cargo to a capsid by linking the cargo to a small molecule that binds
capsid with high affinity, essentially using an antiviral as a targeting device. This method can be applied to
any cargo. In some cases, it is desirable to display cargo on the capsid exterior, in other cases it is desirable
to package it within the capsid. In preliminary data, we demonstrate an approach to making “holey” capsids
that expose the particle interior and can be re-sealed to enclose the contents. Using this same technology,
we can make patches on the capsid surface; this can be used for displaying patches of receptor-binding
ligands or cell-penetrating peptides. Cargo, packaged within a capsid, is not deliverable unless it can be
released. In preliminary data, we developed techniques for triggering capsid disassembly in response to
redox potential, taking advantage of chemically-induced metastability. This same approach can be applied
to other triggering signals. The ultimate goal of these studies is to combine the approaches to a practical
end: we propose to build two model biotech reagents, one to measure antibody levels and the other to
deliver packaged cargo to specific cells. These approaches are each built on an understanding of the
biochemistry and biophysics of HBV capsid assembly.
HBV is one the smallest human pathogens. It is remarkably efficient at packaging its genome and delivering
it to target cells. Based on our understanding of capsid assembly and capsid biophysics, we will develop
approaches to specifically packaging cargo molecules and delivering these reagents intracellularly. The
tools arising from this research will provide a means for man to take advantage of HBV.

## Key facts

- **NIH application ID:** 10899439
- **Project number:** 5R01AI118933-07
- **Recipient organization:** TRUSTEES OF INDIANA UNIVERSITY
- **Principal Investigator:** Adam Zlotnick
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $493,431
- **Award type:** 5
- **Project period:** 2016-03-14 → 2027-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10899439

## Citation

> US National Institutes of Health, RePORTER application 10899439, Multimode Observation of Virus Capsid Assembly (5R01AI118933-07). Retrieved via AI Analytics 2026-07-20 from https://api.ai-analytics.org/grant/nih/10899439. Licensed CC0.

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