ABSTRACT

Duck Tembusu virus (DTMUV), an emergent flavivirus, causes domestic waterfowls to suffer from severe egg-drop syndrome and fatal encephalitis, greatly threatens duck production globally. Like other mosquito-borne flaviviruses, the envelope (E) protein of all DTMUV strains was N-glycosylated at the amino acid position 154. Thus far, the biological roles of DTMUV E glycosylation have remained largely unexplored. Herein, we demonstrated the key roles of E glycosylation in the replication and pathogenicity of DTMUV in ducks by characterizing the reverse-genetics-derived DTMUV wild-type MC strain and MC bearing mutations (N154Q and N154I) that abolish the E glycosylation. Our data showed that the disruption of E glycosylation could substantially impair virus attachment, entry, and infectivity in DEFs and C6/36 cells. Notably, ducks inoculated intracerebrally with the wild-type virus exhibited severe disease onset. In contrast, those inoculated with mutant viruses were mildly affected as manifested by minimal weight loss, no mortality, lower viral loads in the various tissues, and reduced brain lesions. Attenuated phenotypes of the mutant viruses might be partly associated with lower inflammatory cytokines expression in the brains of infected ducks. Our study offers the first evidence that E glycosylation is vital for DTMUV replication, pathogenicity, and neurovirulence in vivo.

摘要

鸭 Tembusu 病毒 (DTMUV) 是一种新兴的黄病毒，可导致家养水禽患上严重的落蛋综合症和致命的脑炎，极大地威胁着全球鸭子的生产。与其他蚊媒黄病毒一样，所有 DTMUV 毒株的包膜 (E) 蛋白在氨基酸位置 154 处被 N-糖基化。迄今为止，DTMUV E 糖基化的生物学作用在很大程度上仍未被探索。在这里，我们通过表征消除 E 糖基化的反向遗传学衍生的 DTMUV 野生型 MC 菌株和带有 MC 的突变（N154Q 和 N154I），证明了 E 糖基化在鸭中 DTMUV 复制和致病性中的关键作用。我们的数据表明，E 糖基化的破坏可显着损害 DEF 和 C6/36 细胞中的病毒附着、进入和感染性。尤其，脑内接种野生型病毒的鸭表现出严重的疾病发作。相比之下，那些接种突变病毒的人受到轻微影响，表现为体重减轻最小、没有死亡率、各种组织中的病毒载量较低以及脑损伤减少。突变病毒的减毒表型可能与受感染鸭脑中较低的炎性细胞因子表达有关。我们的研究提供了第一个证据表明 E 糖基化对 DTMUV 复制、致病性和神经毒力至关重要 突变病毒的减毒表型可能与受感染鸭脑中较低的炎性细胞因子表达有关。我们的研究提供了第一个证据表明 E 糖基化对 DTMUV 复制、致病性和神经毒力至关重要 突变病毒的减毒表型可能与受感染鸭脑中较低的炎性细胞因子表达有关。我们的研究提供了第一个证据表明 E 糖基化对 DTMUV 复制、致病性和神经毒力至关重要在体内。