# Poxvirus manipulation of the host cell protein synthesis machinery

> **NIH NIH R01** · NORTHWESTERN UNIVERSITY · 2021 · $395,000

## Abstract

PROJECT SUMMARY
Humans have a profound, double-edged relationship with poxviruses. On one hand, the devastating effects of
smallpox are unparalleled by any other pathogen in recorded history, and its eradication is a milestone in
modern medicine. On the other, poxviruses are now used as highly effective gene therapy and vaccine vectors
as well as oncolytics in the treatment of cancer. Moreover, molluscum contagiosum is widespread and causes
prolonged, untreatable lesions, while emerging poxviruses are a serious concern. Indeed, smallpox evolved
from a rodent Taterapox virus and zoonotic poxvirus infections resulting in human-to-human transmission are
being reported at an increasing frequency. In some cases smallpox vaccination does not provide protection,
while live smallpox vaccines such as Vaccinia Virus (VacV) pose serious, life-threatening complications for
many individuals. As such, whether it be infection by existing or future poxviruses, zoonotic infections or
complications from therapeutic vectors, it is important to understand how these unusual pathogens replicate.
Unlike most other double-stranded DNA viruses, poxviruses replicate in the cytoplasm of infected cells within
viral factories (VFs). Encoding >200 genes that include their own polymerases, transcription factors and redox
system, poxviruses exhibit remarkable self-sufficiency. Despite this, poxviruses remain absolutely dependent
on gaining access to host ribosomes in order to synthesize viral proteins, representing an exploitable
weakness. Indeed, we have shown previously that VacV activates the host cap-dependent translation
machinery and that this can be targeted using small molecules to suppress virus replication without
cytotoxicity. Our preliminary data identifies a series of new and unexpected modifications induced by VacV.
This includes a viral protein that remodels mammalian Target of Rapamycin (mTOR), a key regulator of
ribosome recruitment and host immune responses, displacing regulatory subunits to render mTOR
constitutively active and beyond host control. In addition, mass spectrometry and dual-color live cell imaging
revealed that VacV phosphorylates the small ribosomal subunit, RACK1 at unique sites not induced by other
viruses or stimuli, and recruits RACK1 to VFs as they form. Moreover, we find that this modification is required
for selective synthesis of late VacV proteins, but not proteins of other viruses, and is induced by a VacV
kinase. Finally, proteomic analysis of ribosome complexes isolated from primary human cells further revealed
that VacV induces highly selective modifications to other ribosomal proteins and to the subunit composition of
ribosomes themselves. Our data suggests that this “ribosome specialization” is important for poxvirus protein
synthesis, and is dispensable to the host. Understanding how these modifications facilitate VacV protein
synthesis will provide important insights into fundamental aspects of poxvirus biology as well as mecha...

## Key facts

- **NIH application ID:** 10054098
- **Project number:** 5R01AI127456-05
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** Derek Walsh
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $395,000
- **Award type:** 5
- **Project period:** 2016-11-23 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10054098

## Citation

> US National Institutes of Health, RePORTER application 10054098, Poxvirus manipulation of the host cell protein synthesis machinery (5R01AI127456-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10054098. Licensed CC0.

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