title: Mutations in the G-H loop region of ephrin-B2 can enhance Nipah virus binding and infection.
abstract: Nipah virus (NiV) and Hendra virus (HeV) are zoonotic paramyxoviruses classified in the genus Henipavirus of the family Paramyxoviridae. The entry of henipaviruses occurs through a pH-independent membrane-fusion mechanism mediated by the cooperation of the viral attachment (G) and fusion (F) envelope glycoproteins following virion binding to susceptible host cells. Virus attachment is mediated by the interaction of the G glycoprotein with ephrin-B2 or ephrin-B3, which were identified as the functional receptors of henipavirus. Several residues of the G glycoprotein that are important for receptor binding have been determined through mutagenesis and structural analyses; however, similar approaches have not been carried out for the viral receptor ephrin-B2. Here, an alanine-scanning mutagenesis analysis was performed to identify residues of ephrin-B2 which are critical for NiV binding and entry by using an NiV-F- and -G-glycoprotein pseudotyped lentivirus assay. Results indicated that the G-H loop of ephrin-B2 was indeed critical for the interaction between ephrin-B2 and NiV-G. Unexpectedly, however, some alanine-substitution mutants located in the G-H loop enhanced the infectivity of the NiV pseudotypes, in particular an L124A mutation enhanced entry >30-fold. Further analysis of the L124A ephrin-B2 mutant demonstrated that an increased binding affinity of the mutant receptor with NiV-G was responsible for the enhanced infectivity of both pseudovirus and infectious virus. In addition, cell lines that were stably expressing the L124A mutant receptor were able to support NiV infection more efficiently than the wild-type molecule, potentially providing a new target-cell platform for viral isolation or virus-entry inhibitor screening and discovery.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China.
authors.forename: Junfa
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organization Livestock Industries, Geelong, Victoria, Australia.
authors.forename: Glenn
authors.initials: G
authors.lastname: Marsh
authors.affiliation: Department of Microbiology, Uniformed Services University, Bethesda, MD 20814, USA.
authors.forename: Dimple
authors.initials: D
authors.lastname: Khetawat
authors.affiliation: Department of Microbiology, Uniformed Services University, Bethesda, MD 20814, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Broder
authors.affiliation: Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organization Livestock Industries, Geelong, Victoria, Australia.
authors.forename: Lin-Fa
authors.initials: LF
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, PR China.
authors.forename: Zhengli
authors.initials: Z
authors.lastname: Shi
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002460:Cell Line; D036388:Ephrin-B2 / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D045405:Nipah Virus / Q000472:pathogenicity*; D011485:Protein Binding; D011991:Receptors, Virus / Q000235:genetics* / Q000378:metabolism*; D018411:Spodoptera; D015678:Viral Structural Proteins / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D036388:Ephrin-B2; D050505:Mutant Proteins; D011991:Receptors, Virus; D015678:Viral Structural Proteins