title: A Polymorphism within the Internal Fusion Loop of the Ebola Virus Glycoprotein Modulates Host Cell Entry.
abstract: The large scale of the Ebola virus disease (EVD) outbreak in West Africa in 2013-2016 raised the question whether the host cell interactions of the responsible Ebola virus (EBOV) strain differed from those of other ebolaviruses. We previously reported that the glycoprotein (GP) of the virus circulating in West Africa in 2014 (EBOV2014) exhibited reduced ability to mediate entry into two nonhuman primate (NHP)-derived cell lines relative to the GP of EBOV1976. Here, we investigated the molecular determinants underlying the differential entry efficiency. We found that EBOV2014-GP-driven entry into diverse NHP-derived cell lines, as well as human monocyte-derived macrophages and dendritic cells, was reduced compared to EBOV1976-GP, although entry into most human- and all bat-derived cell lines tested was comparable. Moreover, EBOV2014 replication in NHP but not human cells was diminished relative to EBOV1976, suggesting that reduced cell entry translated into reduced viral spread. Mutagenic analysis of EBOV2014-GP and EBOV1976-GP revealed that an amino acid polymorphism in the receptor-binding domain, A82V, modulated entry efficiency in a cell line-independent manner and did not account for the reduced EBOV2014-GP-driven entry into NHP cells. In contrast, polymorphism T544I, located in the internal fusion loop in the GP2 subunit, was found to be responsible for the entry phenotype. These results suggest that position 544 is an important determinant of EBOV infectivity for both NHP and certain human target cells.IMPORTANCEThe Ebola virus disease outbreak in West Africa in 2013 entailed more than 10,000 deaths. The scale of the outbreak and its dramatic impact on human health raised the question whether the responsible virus was particularly adept at infecting human cells. Our study shows that an amino acid exchange, A82V, that was acquired during the epidemic and that was not observed in previously circulating viruses, increases viral entry into diverse target cells. In contrast, the epidemic virus showed a reduced ability to enter cells of nonhuman primates compared to the virus circulating in 1976, and a single amino acid exchange in the internal fusion loop of the viral glycoprotein was found to account for this phenotype.
authors.affiliation: Infection Biology Unit, German Primate Center, Göttingen, Germany mhoffmann@dpz.eu spoehlmann@dpz.eu.
authors.forename: Markus
authors.initials: M
authors.lastname: Hoffmann
authors.affiliation: Infection Biology Unit, German Primate Center, Göttingen, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Crone
authors.affiliation: Institute of Virology, Philipps University Marburg, Marburg, Germany.
authors.forename: Erik
authors.initials: E
authors.lastname: Dietzel
authors.affiliation: Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Paijo
authors.affiliation: Infection Biology Unit, German Primate Center, Göttingen, Germany.
authors.forename: Mariana
authors.initials: M
authors.lastname: González-Hernández
authors.affiliation: Infection Biology Unit, German Primate Center, Göttingen, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Nehlmeier
authors.affiliation: Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kalinke
authors.affiliation: Institute of Virology, Philipps University Marburg, Marburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Becker
authors.affiliation: Infection Biology Unit, German Primate Center, Göttingen, Germany mhoffmann@dpz.eu spoehlmann@dpz.eu.
authors.forename: Stefan
authors.identifier: http://orcid.org/0000-0001-6086-9136
authors.initials: S
authors.lastname: Pöhlmann
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D029043:Ebolavirus / Q000235:genetics / Q000472:pathogenicity*; D057809:HEK293 Cells; D019142:Hemorrhagic Fever, Ebola / Q000821:virology; D006801:Humans; D008253:Macaca mulatta; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics*; D053585:Virus Attachment; D053586:Virus Internalization; D014779:Virus Replication / Q000235:genetics
chemical_list: D014759:Viral Envelope Proteins; C113189:envelope glycoprotein, Ebola virus
keywords: Ebola virus; glycoprotein; host cell entry; internal fusion loop