Respiratory syncytial virus G protein CX3C motif impairs human airway epithelial and immune cell responses

J Virol. 2013 Dec;87(24):13466-79. doi: 10.1128/JVI.01741-13. Epub 2013 Oct 2.

Abstract

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory infection in infants and young children and causes disease in the elderly and persons with compromised cardiac, pulmonary, or immune systems. Despite the high morbidity rates of RSV infection, no highly effective treatment or vaccine is yet available. The RSV G protein is an important contributor to the disease process. A conserved CX3C chemokine-like motif in G likely contributes to the pathogenesis of disease. Through this motif, G protein binds to CX3CR1 present on various immune cells and affects immune responses to RSV, as has been shown in the mouse model of RSV infection. However, very little is known of the role of RSV CX3C-CX3CR1 interactions in human disease. In this study, we use an in vitro model of human RSV infection comprised of human peripheral blood mononuclear cells (PBMCs) separated by a permeable membrane from human airway epithelial cells (A549) infected with RSV with either an intact CX3C motif (CX3C) or a mutated motif (CX4C). We show that the CX4C virus induces higher levels of type I/III interferon (IFN) in A549 cells, increased IFN-α and tumor necrosis factor alpha (TNF-α) production by human plasmacytoid dendritic cells (pDCs) and monocytes, and increased IFN-γ production in effector/memory T cell subpopulations. Treatment of CX3C virus-infected cells with the F(ab')2 form of an anti-G monoclonal antibody (MAb) that blocks binding to CX3CR1 gave results similar to those with the CX4C virus. Our data suggest that the RSV G protein CX3C motif impairs innate and adaptive human immune responses and may be important to vaccine and antiviral drug development.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptive Immunity
  • Amino Acid Motifs
  • CX3C Chemokine Receptor 1
  • Chemokines, CX3C / immunology
  • Epithelial Cells / immunology*
  • Epithelial Cells / virology
  • Humans
  • Immunity, Innate
  • Interferons / genetics
  • Interferons / immunology
  • Leukocytes, Mononuclear / immunology*
  • Leukocytes, Mononuclear / virology
  • Receptors, Chemokine / immunology
  • Respiratory Syncytial Virus Infections / genetics
  • Respiratory Syncytial Virus Infections / immunology*
  • Respiratory Syncytial Virus Infections / virology
  • Respiratory Syncytial Virus, Human / chemistry
  • Respiratory Syncytial Virus, Human / genetics
  • Respiratory Syncytial Virus, Human / immunology*
  • Viral Proteins / chemistry
  • Viral Proteins / genetics
  • Viral Proteins / immunology*

Substances

  • CX3C Chemokine Receptor 1
  • CX3CR1 protein, human
  • Chemokines, CX3C
  • Receptors, Chemokine
  • Viral Proteins
  • Interferons