<p>Non-structural protein 1 (NS1) of dengue virus (DENV) harbours two conserved N-glycosylation sites at positions 130 and 207, whose biological roles have remained elusive. Using a clinically relevant mouse model of severe dengue, we showed that DENV that lacked N207 glycans on NS1 was significantly attenuated, and this phenotype was dominant over wild-type virulent DENV. Mice infected with this mutant exhibited accelerated viral clearance, milder lymphopenia and more functional DENV-specific CD8<sup>+</sup> T cells. Bulk and single-cell RNA sequencing, cytokine measurements and immune-phenotyping revealed blunted innate inflammatory responses early post-infection, which correlated with reduced PD-L1 expression on innate immune cells and reduced PD-1<sup>+</sup> T-cells in mice infected with de-glycosylated DENV. PD-1 blockade demonstrated the involvement of premature T-cell apoptosis through the PD-L1/PD-1 axis in DENV pathogenesis. Collectively, our findings support that N207-de-glycosylated NS1 inhibits early inflammatory responses, which restricts PD-L1 upregulation on innate immune cells, which in turn limits PD-L1/PD-1 mediated T-cell apoptosis. Our study uncovers a novel immune evasion strategy and identifies PD-L1/PD-1 as a novel mechanism of dengue immunopathogenesis.</p>

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Glycans on non-structural protein 1 prevent premature T-cell mediated dengue virus clearance

  • Fakhriedzwan Idris,
  • Justin Seng Geap Ooi,
  • Donald Heng Rong Ting,
  • Eunice Tze Xin Tan,
  • Corrine Wan,
  • Peter I Benke,
  • Jan K Marzinek,
  • Jack M Copping,
  • Qin Hui Li,
  • Lu Yi Ng,
  • Sheau Yng Lim,
  • Ian Walsh,
  • Jane R Allison,
  • Peter J Bond,
  • Federico Torta,
  • Terry Nguyen-Khuong,
  • Kuan Rong Chan,
  • Sylvie Alonso

摘要

Non-structural protein 1 (NS1) of dengue virus (DENV) harbours two conserved N-glycosylation sites at positions 130 and 207, whose biological roles have remained elusive. Using a clinically relevant mouse model of severe dengue, we showed that DENV that lacked N207 glycans on NS1 was significantly attenuated, and this phenotype was dominant over wild-type virulent DENV. Mice infected with this mutant exhibited accelerated viral clearance, milder lymphopenia and more functional DENV-specific CD8+ T cells. Bulk and single-cell RNA sequencing, cytokine measurements and immune-phenotyping revealed blunted innate inflammatory responses early post-infection, which correlated with reduced PD-L1 expression on innate immune cells and reduced PD-1+ T-cells in mice infected with de-glycosylated DENV. PD-1 blockade demonstrated the involvement of premature T-cell apoptosis through the PD-L1/PD-1 axis in DENV pathogenesis. Collectively, our findings support that N207-de-glycosylated NS1 inhibits early inflammatory responses, which restricts PD-L1 upregulation on innate immune cells, which in turn limits PD-L1/PD-1 mediated T-cell apoptosis. Our study uncovers a novel immune evasion strategy and identifies PD-L1/PD-1 as a novel mechanism of dengue immunopathogenesis.