---
OA_place: publisher
_id: '18101'
abstract:
- lang: eng
  text: "The Retroviridae family consists of two sub-families, the Orthoretrovirinae
    and the\r\nSpumaretrovirinae. The Orthoretroviruses contain important human pathogens,
    such as the\r\nhuman immunodeficiency virus 1 (HIV-1). They also harbor other
    retrovirus species which\r\nare regularly used as model systems to study the retroviral
    life cycle. The main structural\r\ncomponent of the retroviruses, is the Gag protein
    and its truncation derivatives occurring\r\nduring viral maturation. Orthoretroviral
    Gag assemblies have been extensively studied to\r\nunderstand the interactions
    that confer stability and morphology to viral particles.\r\nThe Spumaretrovirinae
    subfamily represent an early diverging branch of the Retroviridae.\r\nIts members,
    the Foamy viruses (FV), share most of the conventional features found in\r\nretroviruses.
    However, they also possess multiple characteristics that make them unique. In\r\nparticular,
    FV Gag does not get extensively cleaved as in orthoretroviruses. Hence, the Gag\r\narchitecture
    deviates from the canonical domain arrangement in FV. They also exhibit a\r\npeculiar
    particle morphology, having no apparent immature state and a seemingly\r\nicosahedral
    mature particle. Due to this, many fundamental questions on FV structural\r\nassembly
    mechanisms remain open. To answer these questions, was the main focus of this\r\nthesis.\r\nMainly,
    it is not known how FV assemble their core in a virus particle and what are the\r\nimportant
    assembly interaction sites within said core. What is the minimum assembly\r\ncompetent
    domain of FV Gag? Is there a morphological change in the assembly type of FVGag
    lattices? If so, what is defining these morphological shifts? Finally, it would
    be\r\ninteresting to know what is the evolutionary relationship between FV and
    the rest of the\r\nretrotranscribing elements, from a structural point of view?\r\nTo
    answer these questions, membrane-enveloped mammalian cell-derived FV virus-like\r\nparticles
    (VLPs) were produced. Cryo-electron tomography (cryo-ET) analysis suggested\r\nthese
    FV VLPs do not form a canonical retroviral Gag lattice structure, which is in
    line with\r\nearlier observations. To further evaluate FV Gag assembly competence
    and morphology,\r\nthe first bacterial cell-derived in vitro VLP assembly system
    was designed and optimized.\r\nUsing this system with different truncation variants,
    the minimum assembly competent\r\ndomain of FV Gag was found to be the putative
    CA300-477 domain. Varying VLP\r\nmorphologies were also observed and strongly
    suggested residues upstream of CA300-477\r\nplay a role in morphology determination.
    Finally, a combined cryo-electron microscopy (cryoEM) and cryo-ET approach was
    taken to analyze tubular assemblies from the minimal\r\nassembly competent domain.
    This revealed an unexpectedly unique non-canonical\r\nassembly architecture. Three
    novel lattice stabilizing interfaces were described which\r\nproved to be as unique
    as the lattice arrangement. Comparison to a newly published FV CA\r\ncore structure
    revealed the CA-CA interactions in the atypical assembly do not recapitulate\r\nwhat
    is described for the FV core lattice. However, the new in vitro VLP assembly system\r\nobtained
    in this thesis also provides an exciting opportunity to study still unresolved
    FV\r\nassembly features in a potentially facilitated approach compared to conventional
    methods.\r\nIn summary, this work provided a deeper understanding of the basic
    FV Gag assembly unit,\r\nas well as presenting the first FV Gag-derived in vitro
    VLP assembly system. This system\r\nreveals a novel and unique assembly architecture
    among retroviral in vitro assemblies."
acknowledged_ssus:
- _id: EM-Fac
- _id: LifeSc
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Dario J
  full_name: Porley, Dario J
  id: 2FD6EA6C-F248-11E8-B48F-1D18A9856A87
  last_name: Porley
citation:
  ama: Porley Esteves D. Structural characterization of spumavirus capsid assemblies.
    2024. doi:<a href="https://doi.org/10.15479/at:ista:18101">10.15479/at:ista:18101</a>
  apa: Porley Esteves, D. (2024). <i>Structural characterization of spumavirus capsid
    assemblies</i>. Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:18101">https://doi.org/10.15479/at:ista:18101</a>
  chicago: Porley Esteves, Darío. “Structural Characterization of Spumavirus Capsid
    Assemblies.” Institute of Science and Technology Austria, 2024. <a href="https://doi.org/10.15479/at:ista:18101">https://doi.org/10.15479/at:ista:18101</a>.
  ieee: D. Porley Esteves, “Structural characterization of spumavirus capsid assemblies,”
    Institute of Science and Technology Austria, 2024.
  ista: Porley Esteves D. 2024. Structural characterization of spumavirus capsid assemblies.
    Institute of Science and Technology Austria.
  mla: Porley Esteves, Darío. <i>Structural Characterization of Spumavirus Capsid
    Assemblies</i>. Institute of Science and Technology Austria, 2024, doi:<a href="https://doi.org/10.15479/at:ista:18101">10.15479/at:ista:18101</a>.
  short: D. Porley Esteves, Structural Characterization of Spumavirus Capsid Assemblies,
    Institute of Science and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-09-20T10:21:03Z
date_published: 2024-09-26T00:00:00Z
date_updated: 2026-10-02T11:20:53Z
day: '26'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: GradSch
- _id: FlSc
doi: 10.15479/at:ista:18101
doi_confirm: '1'
ec_funded: 1
file:
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  date_updated: 2025-03-25T23:30:03Z
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fulldoi: https://doi.org/10.15479/at:ista:18101
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '131'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '665385'
  name: International IST Doctoral Program
- _id: 9B9C98E0-BA93-11EA-9121-9846C619BF3A
  grant_number: '25762'
  name: Structural characterization of spumavirus capsid assemblies to understand
    conserved Ortervirales assembly mechanisms
publication_identifier:
  isbn:
  - 978-3-99078-041-1
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
researchdata_availability: unclear
status: public
supervisor:
- first_name: Florian KM
  full_name: Schur, Florian KM
  id: 48AD8942-F248-11E8-B48F-1D18A9856A87
  last_name: Schur
  orcid: 0000-0003-4790-8078
supplementarymaterial: unclear
title: Structural characterization of spumavirus capsid assemblies
type: dissertation
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
year: '2024'
...