Fcγ-receptor IIa-mediated Src Signaling Pathway Is Essential for the Antibody-Dependent Enhancement of Ebola Virus Infection

PLoS Pathog. 2016 Dec 30;12(12):e1006139. doi: 10.1371/journal.ppat.1006139. eCollection 2016 Dec.

Abstract

Antibody-dependent enhancement (ADE) of Ebola virus (EBOV) infection has been demonstrated in vitro, raising concerns about the detrimental potential of some anti-EBOV antibodies. ADE has been described for many viruses and mostly depends on the cross-linking of virus-antibody complexes to cell surface Fc receptors, leading to enhanced infection. However, little is known about the molecular mechanisms underlying this phenomenon. Here we show that Fcγ-receptor IIa (FcγRIIa)-mediated intracellular signaling through Src family protein tyrosine kinases (PTKs) is required for ADE of EBOV infection. We found that deletion of the FcγRIIa cytoplasmic tail abolished EBOV ADE due to decreased virus uptake into cellular endosomes. Furthermore, EBOV ADE, but not non-ADE infection, was significantly reduced by inhibition of the Src family protein PTK pathway, which was also found to be important to promote phagocytosis/macropinocytosis for viral uptake into endosomes. We further confirmed a significant increase of the Src phosphorylation mediated by ADE. These data suggest that antibody-EBOV complexes bound to the cell surface FcγRIIa activate the Src signaling pathway that leads to enhanced viral entry into cells, providing a novel perspective for the general understanding of ADE of virus infection.

MeSH terms

  • Animals
  • Antibodies, Viral / immunology
  • Antibody-Dependent Enhancement / immunology*
  • Chlorocebus aethiops
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Hemorrhagic Fever, Ebola / immunology*
  • Hemorrhagic Fever, Ebola / metabolism
  • Humans
  • Jurkat Cells
  • K562 Cells
  • Receptors, IgG / immunology*
  • Signal Transduction / immunology*
  • Vero Cells
  • Virus Internalization
  • src-Family Kinases / immunology*

Substances

  • Antibodies, Viral
  • Fc gamma receptor IIA
  • Receptors, IgG
  • src-Family Kinases

Grants and funding

This work was supported by KAKENHI (14J06186 and 15H01249), Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and the Japan Society for the Promotion of Science (JSPS), Japan, and partly by the Japan Initiative for Global Research Network on Infectious Diseases (J-GRID) from Ministry of Education, Culture, Sport, Science & Technology in Japan, and Japan Agency for Medical Research and Development (AMED), and the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.