Investigating the roles of Influenza A virus NEP protein and its functional interaction with the F1?/β subunits of mitochondria ATP synthase for viral egression

  • 何 佳穎

Student thesis: Master's Thesis

Abstract

Influenza A virus (IAV) is an enveloped virus with a segmented genome of 8 negative sense single-stranded RNAs which encode 11 viral proteins The IAV Nuclear Exporting Protein (NEP) has been reported to involve in virus ribonucleoprotein (vRNP) nuclear export through Nuclear Export Signal (NES)-independent interaction with hCRM1 and can negatively regulate viral genome transcription/replication However the functional relevance of NEP in virus life cycle and possible cellular effects remain largely unknown Our previous results suggested that NEP interacts with many cellular proteins and may have importance in viral egression by interacting with a cellular protein F1?/β ATP synthase Recent studies indeed showed that certain viruses would subvert the cellular immune response or energy resource through mitochondrial protein to promote viral egression In this study we report that NEP is likely a multifunctional protein which may hijack mitochondria ATP synthase by interacting with the F1?/β subunit to modulate cellular IFN response and cellular ATP level for IAV egression First by using in vitro GST pull-down assay and in vivo affinity purification in the presence or absence of RNaseA we found that NEP interacts with ATP synthase in an RNA dependent manner and is associated with vRNP complex during IAV infection We also found that NEP inhibited cellular ATP level and type I IFN response in a dose-dependent manner In addition overexpression of ATP synthase ? subunit enhanced NEP to down-regulate type I IFN response Surprisingly after knockdown or over-expression of ATP synthase ? or β subunit intracellular viral protein production was unaffected yet their expression levels are negatively correlated with the degree of IFN-β response after IAV infection This result most likely indicated that ATP synthase ? and β subunits are required for antagonizing IAV-induced IFN response Moreover knockdown of ATP synthase ? or β subunit resulted in significant decrease of extracellular viral production suggesting that ATP synthase ? and β subunits have functional relevance with viral assembly or budding These results collectively indicated that NEP had a role on extracellular viral production by targeting ? and β subunits through vRNP in an RNA-dependent manner and which may also correlate with the interruption of mitochondria function resulting in the disruption of energy production and innate host immune response that may be critical for viral egress
Date of Award2014 Jun 27
Original languageEnglish
SupervisorShainn-Wei Wang (Supervisor)

Cite this

Investigating the roles of Influenza A virus NEP protein and its functional interaction with the F1?/β subunits of mitochondria ATP synthase for viral egression
佳穎, 何. (Author). 2014 Jun 27

Student thesis: Master's Thesis