# A Novel Cell-based System for the Search of SARS-CoV-2 ORF3a Inhibitors against COVID-19

> **NIH NIH R21** · UNIVERSITY OF MARYLAND BALTIMORE · 2024 · $233,250

## Abstract

Abstract
The COVID-19 pandemic caused by SARS-CoV-2 has presented unprecedented challenges due to its rapid
spread, mutability, high death rate, and long-term complications. Vaccines have shown efficacy but wane over
time, and new variants emerge. Antiviral drugs offer an effective alternative, but their success has been variable,
and the development of drug resistance is a concern. Hence, there is a continued need to identify novel antiviral
drugs for the treatment of COVID-19 and its post-COVID complications.
 Through a comprehensive genome-wide study utilizing a surrogate fission yeast system, we have identified
the ORF3a protein as a promising therapeutic target. ORF3a is known to play a significant role in viral
pathogenesis, contributing to cellular damage in the lungs and kidneys, induction of the NLRP3 inflammasome
and cytokine storm, and the severity of COVID-19. Specifically, our research demonstrates that ORF3a
expression in lung and kidney epithelial cells induces innate cellular oxidative stress and proinflammatory
immune responses, leading to NF-kB-mediated cytokine production of TNFα and IL-6, ultimately resulting in
apoptotic cell death. We refer to these effects collectively as "the cytopathic ORF3a effects."
 Consistent with clinical observations linking the emergence of ORF3a mutants to COVID-19 severity, we have
also observed distinct variations in the cytopathic activities of emerging ORF3a mutants. As oxidative stress and
inflammation contribute to cell death, tissue damage, and the severity of COVID-19, and ORF3a triggers cytokine
storm and upregulation of TNFα and IL-6, which are strong predictors of COVID-19 severity, targeting ORF3a's
cytopathic effects becomes crucial for mitigating the impact of the disease.
 The objective of our study is to develop an integrated system utilizing fission yeast and human cells to identify
human suppressive cellular proteins (hSCPs) and small molecule inhibitors (SMIs) that specifically target ORF3a.
Our approach consists of two main aims: (1) conducting a genome-wide search to identify hSCPs capable of
suppressing ORF3a, and (2) employing a fission yeast cell-based high-throughput screening (HTS) system to
rapidly identify SMIs with therapeutic potential. We hypothesize that direct inhibition of ORF3a using an SMI
will effectively counteract its cytopathic effects, mitigate tissue damage, and reduce the severity of COVID-19.
 Our research team comprises experts in yeast biology, virology, viral infection in BSL-3 containment, HTS drug
discovery, and medicinal chemistry. The novelty of our project lies in the absence of known inhibitors targeting
ORF3a, underscoring the significance of this study. In our preliminary HTS runs, we have identified a SMI S3080,
an FDA-approved antiviral drug Etravirine, as an inhibitor of ORF3a in both fission yeast and mammalian cells,
thereby supporting the feasibility of our proposed HTS study. Successful completion of this research will enable
the identi...

## Key facts

- **NIH application ID:** 10888101
- **Project number:** 1R21AI175931-01A1
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **Principal Investigator:** RICHARD YUQI ZHAO
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $233,250
- **Award type:** 1
- **Project period:** 2024-06-21 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10888101

## Citation

> US National Institutes of Health, RePORTER application 10888101, A Novel Cell-based System for the Search of SARS-CoV-2 ORF3a Inhibitors against COVID-19 (1R21AI175931-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10888101. Licensed CC0.

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