title: The Ebola virus glycoprotein contributes to but is not sufficient for virulence in vivo.
abstract: Among the Ebola viruses most species cause severe hemorrhagic fever in humans; however, Reston ebolavirus (REBOV) has not been associated with human disease despite numerous documented infections. While the molecular basis for this difference remains unclear, in vitro evidence has suggested a role for the glycoprotein (GP) as a major filovirus pathogenicity factor, but direct evidence for such a role in the context of virus infection has been notably lacking. In order to assess the role of GP in EBOV virulence, we have developed a novel reverse genetics system for REBOV, which we report here. Together with a previously published full-length clone for Zaire ebolavirus (ZEBOV), this provides a unique possibility to directly investigate the role of an entire filovirus protein in pathogenesis. To this end we have generated recombinant ZEBOV (rZEBOV) and REBOV (rREBOV), as well as chimeric viruses in which the glycoproteins from these two virus species have been exchanged (rZEBOV-RGP and rREBOV-ZGP). All of these viruses could be rescued and the chimeras replicated with kinetics similar to their parent virus in tissue culture, indicating that the exchange of GP in these chimeric viruses is well tolerated. However, in a mouse model of infection rZEBOV-RGP demonstrated markedly decreased lethality and prolonged time to death when compared to rZEBOV, confirming that GP does indeed contribute to the full expression of virulence by ZEBOV. In contrast, rREBOV-ZGP did not show any signs of virulence, and was in fact slightly attenuated compared to rREBOV, demonstrating that GP alone is not sufficient to confer a lethal phenotype or exacerbate disease in this model. Thus, while these findings provide direct evidence that GP contributes to filovirus virulence in vivo, they also clearly indicate that other factors are needed for the acquisition of full virulence.
authors.affiliation: Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
authors.forename: Allison
authors.initials: A
authors.lastname: Groseth
authors.forename: Andrea
authors.initials: A
authors.lastname: Marzi
authors.forename: Thomas
authors.initials: T
authors.lastname: Hoenen
authors.forename: Astrid
authors.initials: A
authors.lastname: Herwig
authors.forename: Don
authors.initials: D
authors.lastname: Gardner
authors.forename: Stephan
authors.initials: S
authors.lastname: Becker
authors.forename: Hideki
authors.initials: H
authors.lastname: Ebihara
authors.forename: Heinz
authors.initials: H
authors.lastname: Feldmann
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D029043:Ebolavirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D019142:Hemorrhagic Fever, Ebola / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D013045:Species Specificity; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D006023:Glycoproteins; D014764:Viral Proteins; D037521:Virulence Factors