Show simple item record

Files in this item

Thumbnail

Item metadata

dc.contributor.advisorRandall, R. E.
dc.contributor.authorHale, Benjamin G.
dc.coverage.spatial243en
dc.date.accessioned2008-05-15T10:37:30Z
dc.date.available2008-05-15T10:37:30Z
dc.date.issued2007-09-28
dc.identifieruk.bl.ethos.552074
dc.identifier.urihttps://hdl.handle.net/10023/483
dc.description.abstractThe influenza A virus non-structural (NS1) protein is multifunctional, and during virus-infection NS1 interacts with several factors in order to manipulate host-cell processes. This study reports that NS1 binds directly to p85β, a regulatory subunit of phosphoinositide 3-kinase (PI3K), but not to the related p85α. Expression of NS1 was sufficient to activate PI3K and cause the phosphorylation of a downstream mediator of PI3K signalling, Akt. However, in virus-infected MDCK cells, the kinetics of Akt phosphorylation did not correlate with NS1 expression, and suggested that negative regulation of this signalling pathway occurs subsequent to ~8h post-infection. Mapping studies showed that the NS1:p85β interaction is primarily mediated by the NS1 C-terminal domain and the p85β inter-SH2 (Src homology 2) domain. Additionally, the highly conserved tyrosine at residue 89 (Y89) of NS1 was found to be important for binding and activating PI3K in a phosphorylation-independent manner. The inter-SH2 domain of p85β is a coiled-coil structure that acts as a scaffold for the p110 catalytic subunit of PI3K. As NS1 does not displace p110 from the inter-SH2 domain, a model is proposed whereby NS1 forms an active heterotrimeric complex with PI3K, and disrupts the ability of p85β to control p110 function. Biological studies revealed that a mutant influenza A virus (Udorn/72) expressing NS1 with phenylalanine substituted for tyrosine-89 (Y89F) exhibited a small-plaque phenotype, and grew more slowly in MDCK cells than wild-type virus. Unexpectedly, another mutant influenza A virus strain (WSN/33) expressing NS1-Y89F was not attenuated in MDCK cells, yet appeared to be less pathogenic than wild-type in vivo. Overall, these data indicate a role for NS1-mediated PI3K activation in efficient influenza A virus replication. The potential application of this work to the design of novel anti-influenza drugs and vaccine production is discussed.en
dc.format.extent2675 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherUniversity of St Andrews
dc.subjectInfluenzaen
dc.subjectVirusen
dc.subjectPI3Ken
dc.subjectAkten
dc.subjectVaccineen
dc.subjectAnti-viralsen
dc.subject.lccQR470.H2
dc.subject.lcshInfluenza A virusen
dc.subject.lcshCellular signal transductionen
dc.subject.lcshPhosphoinositidesen
dc.subject.lcshViruses--Reproductionen
dc.titleInfluenza A viruses and PI3K signallingen
dc.typeThesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen
dc.publisher.institutionThe University of St Andrewsen


This item appears in the following Collection(s)

Show simple item record