A single mutation in the envelope protein modulates flavivirus antigenicity, stability, and pathogenesis

PLoS Pathog. 2017 Feb 16;13(2):e1006178. doi: 10.1371/journal.ppat.1006178. eCollection 2017 Feb.


The structural flexibility or 'breathing' of the envelope (E) protein of flaviviruses allows virions to sample an ensemble of conformations at equilibrium. The molecular basis and functional consequences of virus conformational dynamics are poorly understood. Here, we identified a single mutation at residue 198 (T198F) of the West Nile virus (WNV) E protein domain I-II hinge that regulates virus breathing. The T198F mutation resulted in a ~70-fold increase in sensitivity to neutralization by a monoclonal antibody targeting a cryptic epitope in the fusion loop. Increased exposure of this otherwise poorly accessible fusion loop epitope was accompanied by reduced virus stability in solution at physiological temperatures. Introduction of a mutation at the analogous residue of dengue virus (DENV), but not Zika virus (ZIKV), E protein also increased accessibility of the cryptic fusion loop epitope and decreased virus stability in solution, suggesting that this residue modulates the structural ensembles sampled by distinct flaviviruses at equilibrium in a context dependent manner. Although the T198F mutation did not substantially impair WNV growth kinetics in vitro, studies in mice revealed attenuation of WNV T198F infection. Overall, our study provides insight into the molecular basis and the in vitro and in vivo consequences of flavivirus breathing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / immunology
  • Antigens, Viral / genetics
  • Antigens, Viral / immunology*
  • Dengue / genetics
  • Dengue / immunology
  • Dengue Virus / genetics
  • Dengue Virus / immunology
  • Dengue Virus / pathogenicity*
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes, B-Lymphocyte / genetics
  • Epitopes, B-Lymphocyte / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Mutation*
  • Neutralization Tests
  • Protein Stability
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / immunology*
  • Virulence / genetics
  • Virulence / immunology
  • West Nile Fever / genetics
  • West Nile Fever / immunology
  • West Nile virus / genetics
  • West Nile virus / immunology
  • West Nile virus / pathogenicity*


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Antigens, Viral
  • Epitopes, B-Lymphocyte
  • Viral Envelope Proteins
  • glycoprotein E, Flavivirus