Ebola virus glycoprotein GP is not cytotoxic when expressed constitutively at a moderate level.
Transient expression of Ebola virus (EBOV) glycoprotein GP causes downregulation of surface proteins, cell rounding and detachment, a phenomenon believed to play a central role in the pathogenicity of the virus. In this study, evidence that moderate expression of GP does not result in such morphological changes was provided. It was shown that GP continuously produced in 293T cells from the Kunjin virus replicon was correctly processed and transported to the plasma membrane without affecting the surface expression of beta1 and alpha5 integrins and major histocompatibility complex I molecules. The level of GP expression in Kunjin replicon GP-expressing cells was similar to that observed in cells infected with EBOV early in infection and lower than that produced in cells transfected with plasmid DNA, phCMV-GP, expressing GP from a strong promoter. Importantly, transient transfection of Kunjin replicon GP-expressing cells with GP-coding plasmid DNA resulted in overexpression of GP, which lead to the downregulation of surface molecules and massive rounding and detachment of transfected cells. Here, it was also demonstrated that cell rounding and downregulation of the surface markers are the late events in EBOV infection, whereas synthesis and massive release of virus particles occur at early steps and do not cause significant cytotoxic effects. These findings indicate that the synthesis of EBOV GP in virus-infected cells is controlled well by several mechanisms that do not allow GP overexpression and hence the early appearance of its cytotoxic properties.
Alazard-Dany
Nathalie
N
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Volchkova
Valentina
V
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Reynard
Olivier
O
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Carbonnelle
Caroline
C
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Dolnik
Olga
O
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Ottmann
Michèle
M
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
Khromykh
Alexander
A
School of Molecular and Microbial Sciences, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
Volchkov
Viktor E
VE
Filovirus Laboratory, Claude Bernard University Lyon 1, INSERM U758, IFR 128 BioSciences Lyon-Gerland, 21 avenue Tony Garnier, 69365 Lyon Cedex 07, France.
D000818:Animals; D002460:Cell Line; D003588:Cytopathogenic Effect, Viral; D029043:Ebolavirus / Q000378:metabolism / Q000502:physiology*; D019142:Hemorrhagic Fever, Ebola / Q000821:virology*; D006801:Humans; D007668:Kidney; D014759:Viral Envelope Proteins / Q000378:metabolism*
D014759:Viral Envelope Proteins; C113189:envelope glycoprotein, Ebola virus