# Imaging of Single HIV-1 Uncoating and Transport to the nucleus

> **NIH NIH R01** · EMORY UNIVERSITY · 2020 · $496,584

## Abstract

Disassembly of the cone-shaped HIV-1 capsid after virus-cell fusion is a prerequisite for
establishing a life-long infection. This step in HIV-1 entry, referred to as uncoating, is critical yet
poorly understood. We have recently developed a novel strategy to visualize HIV-1 uncoating that
is based on a fluorescently tagged oligomeric form of a capsid-binding host protein cyclophilin A
(CypA-DsRed). CypA-DsRed, which is specifically packaged into virions through the high-avidity
binding to the HIV-1 capsid, does not compromise the infectivity. This probe remains associated
with cores after virus-cell fusion and is released upon uncoating. Supporting this notion is our
finding that the rate of CypA-DsRed loss from individual post-fusion cores is modulated by
mutations affecting the core stability and is accelerated by reverse transcription. The CypA-DsRed
based imaging assay revealed a biphasic kinetic of HIV-1 uncoating, with a large number of cores
shedding the capsid protein shortly after fusion. This assay also revealed marked differences in
the uncoating phenotype in HeLa-derived cells and primary human macrophages. We propose
to: (1) delineate CypA-DsRed interactions with HIV-1 core through functional and structural
studies of CypA-DsRed/capsid complexes; (2) elucidate the relationship between reverse
transcription and single core uncoating; and (3) investigate regulation of HIV-1 uncoating by host
factors, such as Nup358 and CPSF6. These studies, employing a combination of genetic,
biochemical and advanced imaging tools, are expected to provide critical insights into the
dynamics and regulation of HIV-1 uncoating in living cells.

## Key facts

- **NIH application ID:** 9868882
- **Project number:** 5R01AI129862-04
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Gregory B Melikian
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $496,584
- **Award type:** 5
- **Project period:** 2017-03-24 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9868882

## Citation

> US National Institutes of Health, RePORTER application 9868882, Imaging of Single HIV-1 Uncoating and Transport to the nucleus (5R01AI129862-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9868882. Licensed CC0.

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