Idris Fakhriedzwan, Ooi Justin Seng Geap, Ting Donald Heng Rong, Tan Eunice Tze Xin, Wan Corrine, Benke Peter I, Marzinek Jan K, Copping Jack M, Li Qin Hui, Ng Lu Yi, Lim Sheau Yng, Walsh Ian, Allison Jane R, Bond Peter J, Torta Federico, Nguyen-Khuong Terry, Chan Kuan Rong, Alonso Sylvie
Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117545, Singapore.
Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, 117456, Singapore.
EMBO Mol Med. 2025 Sep 17. doi: 10.1038/s44321-025-00311-6.
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.
登革病毒（DENV）的非结构蛋白1（NS1）在第130位和第207位含有两个保守的N-糖基化位点，其生物学作用一直难以捉摸。我们使用一种临床相关的严重登革热小鼠模型，发现NS1上缺乏N207聚糖的DENV显著减毒，且这种表型比野生型强毒DENV更具优势。感染这种突变体的小鼠表现出病毒清除加速、淋巴细胞减少较轻以及更具功能的DENV特异性CD8 T细胞。大量和单细胞RNA测序、细胞因子测量以及免疫表型分析显示，感染后早期先天炎症反应减弱，这与去糖基化DENV感染的小鼠中先天免疫细胞上PD-L1表达降低以及PD-1 T细胞减少相关。PD-1阻断证明了在DENV发病机制中通过PD-L1/PD-1轴过早的T细胞凋亡的参与。总体而言，我们的研究结果支持N207去糖基化的NS1抑制早期炎症反应，这限制了先天免疫细胞上PD-L1的上调，进而限制了PD-L1/PD-1介导的T细胞凋亡。我们的研究揭示了一种新的免疫逃逸策略，并确定PD-L1/PD-1是登革热免疫发病机制的一种新机制。
