The Hemagglutinin of Bat-Associated Influenza Viruses Is Activated by TMPRSS2 for pH-Dependent Entry into Bat but Not Human Cells

PLoS One. 2016 Mar 30;11(3):e0152134. doi: 10.1371/journal.pone.0152134. eCollection 2016.

Abstract

New World bats have recently been discovered to harbor influenza A virus (FLUAV)-related viruses, termed bat-associated influenza A-like viruses (batFLUAV). The internal proteins of batFLUAV are functional in mammalian cells. In contrast, no biological functionality could be demonstrated for the surface proteins, hemagglutinin (HA)-like (HAL) and neuraminidase (NA)-like (NAL), and these proteins need to be replaced by their human counterparts to allow spread of batFLUAV in human cells. Here, we employed rhabdoviral vectors to study the role of HAL and NAL in viral entry. Vectors pseudotyped with batFLUAV-HAL and -NAL were able to enter bat cells but not cells from other mammalian species. Host cell entry was mediated by HAL and was dependent on prior proteolytic activation of HAL and endosomal low pH. In contrast, sialic acids were dispensable for HAL-driven entry. Finally, the type II transmembrane serine protease TMPRSS2 was able to activate HAL for cell entry indicating that batFLUAV can utilize human proteases for HAL activation. Collectively, these results identify viral and cellular factors governing host cell entry driven by batFLUAV surface proteins. They suggest that the absence of a functional receptor precludes entry of batFLUAV into human cells while other prerequisites for entry, HAL activation and protonation, are met in target cells of human origin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chiroptera
  • Chlorocebus aethiops
  • Cricetinae
  • Dogs
  • HEK293 Cells
  • Hemagglutinin Glycoproteins, Influenza Virus / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Influenza A virus / physiology*
  • Madin Darby Canine Kidney Cells
  • Serine Endopeptidases / physiology*
  • Transduction, Genetic
  • Vero Cells
  • Viral Tropism
  • Virus Internalization

Substances

  • Hemagglutinin Glycoproteins, Influenza Virus
  • Serine Endopeptidases
  • TMPRSS2 protein, human

Grants and funding

This work was supported by the Deutsche Forschungsgemeinschaft (DFG) grant PO 716/6-1, Gӧttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Deutsche Forschungsgemeinschaft (DFG) grants GSC 226/1 and GSC 226/2 (www.dfg.de). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.