Characterisation of the host response to Puumala virus infection

Koudriakova, Elina (2018) Characterisation of the host response to Puumala virus infection. PhD thesis, University of Glasgow.

Due to Embargo and/or Third Party Copyright restrictions, this thesis is not available in this service.
Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b3322913

Abstract

The family Hantaviridae, of the Bunyavirales order, contains many important human
pathogens of which Puumala virus (PUUV) is the most widely distributed member in
Europe. It causes nephropathia epidemica, a milder form of haemorrhagic fever with renal
syndrome and mortality rates of up to 1% have been reported. They are enveloped viruses,
with a tripartite single-stranded negative sense RNA genome, that replicate solely in the cell
cytoplasm. Several factors have been proposed to play a role in hantavirus pathogenicity,
including regulation of innate immune responses, cell signalling and enhancement of
endothelial cell permeability.
The work presented in this thesis describes biological and molecular characterisation of the
mechanisms behind a hantavirus infection. Transcriptome analysis was a valuable tool that
allowed the investigation of the broader picture of the effect of PUUV on the host cell. 549
and as many as 7,283 genes were differentially expressed at 24 and 48 hours post infection,
respectively, in PUUV-infected cells, revealing extensive transcriptional change. By 48
hours normal cellular function appeared severely disrupted. Most genes involved in
mitochondrial functioning were down-regulated, suggesting a reduced cellular energy level.
Dysregulation of an important signalling hub such as mitochondria might have a more global
impact on cellular functions, consistent with findings in this study. Intrinsic apoptosis
pathway, which is mediated by mitochondria, appeared inhibited. Whereas, death receptor
signalling was activated. Pathways associated with actin formation, organisation and
signalling also appeared inhibited. Members of Rho family of GTPases, which are key
regulators of actin dynamics, were down-regulated overall. Furthermore, integrin signalling,
which mediates Rho GTPase activity, was also inhibited. Immunofluorescence studies
revealed marked morphological changes in mitochondria and substantial remodelling of the
actin cytoskeleton. Further analysis revealed a direct interaction between PUUV N protein
and anillin, a scaffolding protein that mediates formation and organisation of actin filaments,
suggesting a potential novel mechanism behind actin cytoskeleton reorganisation.
Biological interferon (IFN) assays enabled the identification of two IFN antagonists encoded
by PUUV, the cytoplasmic tail of the Gn glycoprotein and the non-structural protein, NSs.
The Gn tail inhibited type I IFN induction at the level of TRAF3-TBK, in agreement with
previous studies on other hantaviruses. Whereas, NSs was found to block IFN induction
downstream of IRF3, suggesting it was able to disrupt transcription or translation. Utilising
immunofluorescence and chromatin immunoprecipitation methods, it was found that PUUV
NSs possessed a potential mechanism to inhibit transcription by blocking serine 2
phosphorylation at the C-terminal domain of RNA polymerase II in a similar manner to the
previously described Bunyamwera virus NSs. The data presented in this thesis illustrates
the broad range of mechanisms employed by PUUV to alter cell function to aid virus
replication and subvert innate immune responses.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: virus, Puumala, innate immunity, host response.
Subjects: Q Science > Q Science (General)
Q Science > QR Microbiology
Q Science > QR Microbiology > QR355 Virology
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Supervisor's Name: Willett, Prof. Brian and Elliott, Prof Richard M. and Wilson, Dr. Sam
Date of Award: 2018
Embargo Date: 5 September 2021
Depositing User: Mrs Marie Cairney
Unique ID: glathesis:2018-30771
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Sep 2018 13:42
Last Modified: 16 Feb 2020 16:45
URI: http://theses.gla.ac.uk/id/eprint/30771

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