# Project 2 - Mechanisms of Hepatitis B Virus Replication

> **NIH NIH P01** · UNIVERSITY OF WISCONSIN-MADISON · 2021 · $384,453

## Abstract

PROJECT 2 ؘ– PROJECT SUMMARY/ABSTRACT
Hepatitis B virus (HBV) chronically infects 250 - 350 million people worldwide, causing most liver cancers, the
second leading cause of cancer death in men and a major cancer in women. HBV maintains these chronic
infections and induces cancer by active replication through poorly understood pathways that traffic viral DNA
and RNAs between the nucleus and cytoplasm, and direct successive interactions of key viral and cell factors in
the cytoplasm for capsid assembly, reverse transcription, envelopment and secretion. In this project, we will
build on our striking new HBV discoveries and newly developed advanced imaging and other research tools to
advance key issues in HBV biology, thus providing essential foundations for critically needed new approaches
to disrupt HBV chronic infections and thus block development of HBV-induced liver cancers.
Aim 1 will define the sites and transport connections of key HBV capsid assembly, maturation and budding steps
in the cytoplasm, including where HBV polymerase (Pol) and pregenomic RNA (pgRNA) interact and are
encapsidated, and where capsids undergo successive steps in reverse transcription, interact with viral envelope
proteins, and bud into the secretory pathway. The results will integrate powerfully with parallel cryo-EM studies
that we are performing with our collaborator Adam Zlotnick (Indiana Univ.) of the nano-scale structures of
maturing capsids at each matched step, revealing in a multi-scale vision of HBV replication how these structural
changes are translated into cell biology effects.
Aim 2 will yield the first full analysis of HBV cccDNA trafficking, maintenance, mitotic segregation and
transcription in the nucleus, and the unprecedented pulsiform nuclear export of HBV pgRNA that we recently
discovered. These results will provide foundations for rational development of treatments targeting cccDNA as
the main genome reservoir of chronic infection, and pgRNA export as an increasingly attractive control point.
Aim 3 will define the basis and functions of our exciting new discoveries that most HBV Pol localizes to
mitochondria for roles independent of reverse transcription, and that Pol stimulates production of mitochondrially
active ceramides that promote apoptosis and mitophagy. The results will inform if and how this association
supports Pol’s multiple emerging functions in modulating mitochondrially-linked innate immune responses, which
has potential implications for HBV control and for the chronic inflammation that contributes to HBV oncogenesis.

## Key facts

- **NIH application ID:** 10149956
- **Project number:** 5P01CA022443-44
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** DANIEL D LOEB
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $384,453
- **Award type:** 5
- **Project period:** 1997-02-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10149956

## Citation

> US National Institutes of Health, RePORTER application 10149956, Project 2 - Mechanisms of Hepatitis B Virus Replication (5P01CA022443-44). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10149956. Licensed CC0.

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