Characterization of African bat henipavirus GH-M74a glycoproteins

J Gen Virol. 2014 Mar;95(Pt 3):539-548. doi: 10.1099/vir.0.060632-0. Epub 2013 Dec 2.

Abstract

In recent years, novel henipavirus-related sequences have been identified in bats in Africa. To evaluate the potential of African bat henipaviruses to spread in non-bat mammalian cells, we compared the biological functions of the surface glycoproteins G and F of the prototype African henipavirus GH-M74a with those of the glycoproteins of Nipah virus (NiV), a well-characterized pathogenic member of the henipavirus genus. Glycoproteins are central determinants for virus tropism, as efficient binding of henipavirus G proteins to cellular ephrin receptors and functional expression of fusion-competent F proteins are indispensable prerequisites for virus entry and cell-to-cell spread. In this study, we analysed the ability of the GH-M74a G and F proteins to cause cell-to-cell fusion in mammalian cell types readily permissive to NiV or Hendra virus infections. Except for limited syncytium formation in a bat cell line derived from Hypsignathus monstrosus, HypNi/1.1 cells, we did not observe any fusion. The highly restricted fusion activity was predominantly due to the F protein. Whilst GH-M74a G protein was found to interact with the main henipavirus receptor ephrin-B2 and induced syncytia upon co-expression with heterotypic NiV F protein, GH-M74a F protein did not cause evident fusion in the presence of heterotypic NiV G protein. Pulse-chase and surface biotinylation analyses revealed delayed F cleavage kinetics with a reduced expression of cleaved and fusion-active GH-M74a F protein on the cell surface. Thus, the F protein of GH-M74a showed a functional defect that is most likely caused by impaired trafficking leading to less efficient proteolytic activation and surface expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa
  • Animals
  • Chiroptera / metabolism
  • Chiroptera / virology*
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • Henipavirus / classification
  • Henipavirus / genetics
  • Henipavirus / isolation & purification*
  • Henipavirus / metabolism*
  • Henipavirus Infections / metabolism
  • Henipavirus Infections / veterinary*
  • Henipavirus Infections / virology
  • Nipah Virus / genetics
  • Nipah Virus / metabolism
  • Receptors, Virus / metabolism
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*

Substances

  • F protein, Nipah virus
  • Glycoproteins
  • Receptors, Virus
  • Viral Envelope Proteins
  • Viral Proteins