# Determining the Molecular Basis for HIV-1 Retrograde Trafficking

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $811,480

## Abstract

PROJECT SUMMARY
During HIV-1 infection, the viral membrane fuses with the host cell membrane to deliver the HIV-1 virus to the
host cell cytoplasm. Once within the host cell, HIV-1 must move to the nucleus so that the viral DNA generated
by reverse transcription can be incorporated into the host genome. The host microtubule network and the
microtubule-associated motor dynein support infection by facilitating HIV-1 transport to the nucleus. This
proposal aims to determine how HIV-1 exploits the dynein machinery during transit to the nucleus. Dynein
cannot walk on microtubules unless bound to a class of proteins called adaptors. In addition to activating
dynein, adaptors also link dynein to cargo. Previously, it was hypothesized that HIV-1 bound to the adaptor
BicD2 to hijack the dynein motor. We used single-molecule total internal reflection fluorescence (TIRF)
microscopy to reconstitute HIV-1 motility via dynein. Unexpectedly, we found HIV-1 cores bind to dynein
directly, unlike host-derived cargoes that require an adaptor to bind to the dynein motor. We also found that
HIV-1 cores can “hijack” and move with dynein motors bound to many divergent adaptors. Attaching directly to
the dynein motor is likely a viral adaptation that ensures HIV-1 can exploit multiple dynein cargo adaptors for
motility in situ. Our long-term goal is to understand the molecular basis of the dynein-mediated trafficking of
HIV-1 so that we can eventually develop tools that disrupt the translocation of HIV-1 to the host nucleus
without affecting native host trafficking. To facilitate this goal, we have developed the following Aims. In Aim 1,
we will use the TIRF-based motility assay we developed to determine how HIV-1 recruits and activates
retrograde motility via dynein and associated adaptors. We will also determine if HIV-1 hitchhiking on dynein-
cargo complexes affects normal dynein-mediated cargo trafficking. In Aim 2, we will use single particle cryo-
EM and cryo-electron tomography of dynein-HIV-1 complexes assembled in vitro to determine the binding site
of dynein on the HIV-1 capsid lattice. Biochemical studies in our lab suggest that dynein has two binding sites
for HIV-1: the heavy chain dimerization domain and the intermediate/light chains. We will characterize this
interaction using individual components bound to HIV-1 capsid in addition to cryo-electron tomography of
dynein-HIV-1 complexes on microtubules in vitro. Finally, in Aim 3, we will determine the cargo adaptors that
HIV-1 exploits in T-cells and determine if flexible use of dynein cargo adaptors facilitates replication in other
cell types. These Aims will show how HIV-1 utilizes a direct interaction with dynein as a flexible platform to
navigate the cytoplasm to the host cell nucleus. These experiments will continue to expand our understanding
of early steps in HIV-1 replication by providing a framework to understand how HIV-1 reaches the host cell
nucleus.

## Key facts

- **NIH application ID:** 11013497
- **Project number:** 1R01AI183968-01A1
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Edward M. Campbell
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $811,480
- **Award type:** 1
- **Project period:** 2024-06-01 → 2029-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11013497

## Citation

> US National Institutes of Health, RePORTER application 11013497, Determining the Molecular Basis for HIV-1 Retrograde Trafficking (1R01AI183968-01A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/11013497. Licensed CC0.

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