Analysis of the Interaction of Orthoflaviviruses with Glycerophospholipid Metabolism and Lipid Droplets
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Date
2025-10-21
Publisher
Philipps-Universität Marburg
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Abstract
The genus orthoflavivirus within the family of Flaviviridae includes some of the most important
emerging and re-emerging human pathogens that substantially contribute to global morbidity
and mortality rates. Important human pathogenic representatives of this genus are e.g., the
viscerotropic dengue virus (DENV) and yellow fever virus (YFV), as well as the neurotropic
West Nile (WNV), Zika (ZIKV), and tick-borne encephalitis virus (TBEV). The orthoflavivirus
replication cycle is tightly connected to host cellular lipid metabolism with dependencies on
e.g. lipid droplets (LDs), membranes of the endoplasmic reticulum, or host cellular proteins.
Here we aimed to understand how orthoflaviviruses interact with LDs and remodel the host cell
lipidome during infection.
To investigate how orthoflaviviruses change the host cell lipidome, we performed shotgun
lipidomics of a set of different viscerotropic, as well as neurotropic orthoflaviviruses to compare
common and distinct changes induced by these viruses, namely ZIKV, WNV, TBEV, DENV,
and YFV-17D. In our cell culture model, we observed strong remodeling of the lipidome upon
infection. In detail, ceramide level largely increased for viruses causing a cytopathic effect, and
triglycerides decreased for all viruses analyzed, resulting in fewer LDs. Additionally, fatty acid
desaturation as well as glycerophospholipid metabolism were significantly altered. Using
shRNA-mediated knockdown approaches and inhibitors, we showed that depletion of enzymes
involved in phosphatidylserine metabolism as well as phosphatidylinositol biosynthesis are
crucial for orthoflaviviruses, since depletion of key enzymes reduced orthoflavivirus titers and
cytopathic effects. Especially knockdown of enzymes PTDSS1/2 and CDIPT showed panorthoflaviviral
effects.
To get more insight into the interaction of LDs with orthoflaviviral C proteins, we first individually
expressed C proteins of ZIKV, WNV, TBEV, DENV, and YFV-17D and analyzed their
subcellular localization. C proteins of all tested orthoflaviviruses localized to cLDs; interestingly
ZIKV C behaved different and showed an additional localization to nLDs, a phenotype that was
not observed for the other orthoflaviviruses. This localization was not common to all ZIKV
strains but was strain-dependent for the Asian ZIKV lineage in infection and single C
expression experiments. In addition, ZIKV PRVABC-59 but not ZIKV MR766 infection
increased the number and size of nLDs. Based on their origin and different marker proteins,
nLDs are divided into NR-luminal and nucleoplasmic LDs. The absence of luminal marker
proteins indicates that ZIKV PRVABC-59 C positive nLDs are nucleoplasmic rather than NRluminal
LDs. We also expressed ZIKV C in S. cerevisiae to analyze if localization to LDs and
LD subtypes is conserved independent of the cell system. Interestingly and in contrast to Huh7
cells, ZIKV C of both strains localized to both LD subtypes in S. cerevisiae.
In summary, the first study underscores the significant remodeling of host cell lipid metabolism
by orthoflaviviruses to support efficient replication, highlighting metabolic enzymes as potential
antiviral targets. Both studies show that although orthoflaviviruses share similar patterns, some
viruses exhibit specific phenotypes that might contribute to enhanced pathogenicity or other
adaptive advantages.
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Dates
Created: 2025Issued: 2025-10-21Updated: 2025-10-21
Faculty
Medizin
Language
eng
Data types
DoctoralThesis
DDC-Numbers
570
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Bierau, Laura (0000-0002-2292-5819): Analysis of the Interaction of Orthoflaviviruses with Glycerophospholipid Metabolism and Lipid Droplets. : Philipps-Universität Marburg 2025-10-21. DOI: https://doi.org/10.17192/z2025.0165.
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