CD300lf Conditional Knockout Mouse Reveals Strain-Specific Cellular Tropism of Murine Norovirus
CD300lf Conditional Knockout Mouse Reveals Strain-Specific Cellular Tropism of Murine Norovirus
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DOI：
10.1128/jvi.01652-20
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发表时间：
2021-02-01
影响因子：
5.4
通讯作者：
Wilen, Craig B.
中科院分区：
文献类型：
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作者：
Graziano, Vincent R.;Alfajaro, Mia Madel;Wilen, Craig B.
诺如病毒是人类和小鼠胃肠道感染的主要原因。了解人类诺如病毒 (HuNoV) 细胞趋向性对于我们了解病毒发病机制具有重要意义。鼠诺如病毒 (MNoV) 被广泛用作 HuNoV 的替代模型。我们之前确定 CD300lf 是 MNoV 的受体。在这里，我们生成了 Cd300lf 条件敲除 (CD300lf(F/F)) 小鼠，以阐明鼠诺如病毒持久性和非持久性毒株的细胞向性。使用该小鼠模型，我们证明了肠上皮细胞（IEC5），特别是簇细胞上的 Cd300lf 表达对于持久性 MNoV 株 CR6（MNoVCR6）在体内的传播至关重要。相比之下，非持续性 MNoV 毒株 CW3 (MNoVCW3) 不需要 IEC 上表达 CD300lf 即可感染。然而，骨髓单核细胞 (LysM Cre+) 中 CD300lf 的缺失部分降低了淋巴和肠道组织中的 CW3 病毒载量。 B 细胞 (CD19 Cre)、中性粒细胞 (Mrp8 Cre) 和树突状细胞 (CD11c Cre) 上 CD300lf 表达的破坏不会影响 MNoVCW3 病毒 RNA 水平。最后，我们发现对先天免疫反应至关重要的转录因子 STAT1 部分限制了 MNoVCW3 对 LysM+ 细胞的细胞趋向性。综上所述，这些数据表明簇细胞上的 CD300lf 表达对于 MNoVCR6 至关重要；骨髓单核细胞是 MNoVCW3 的主要但不是唯一的靶细胞；并且 STAT1 信号传导限制了 MNoVCW3 的细胞向性。这项研究为研究 CD300lf 在诺如病毒发病机制中的细胞类型特异性作用提供了第一个遗传系统。 重要性 人类诺如病毒 (HuNoV) 是胃肠炎的主要原因，每年导致多达 20 万人死亡。 HuNoV 在免疫功能正常的人类中的受体和细胞趋向性尚不清楚。我们使用鼠诺如病毒 (MNoV) 作为 HuNoV 的模型。我们最近确定 CD300If 是 MNoV 的唯一生理受体。在这里，我们利用这一发现来生成 Cd300lf 条件敲除小鼠，以破译特定细胞类型对 MNoV 感染的贡献。我们证明持久的 MNoVCR6 需要簇细胞上的 CD300If 表达。相比之下，以骨髓单核细胞为主的多种 CD300lf+ 细胞类型足以进行非持续性 MNoVCW3 感染。上皮细胞、B 细胞、中性粒细胞和树突状细胞上的 CD300lf 表达对于 MNoVCW3 感染并不重要。 Stat1(-/-) 小鼠中与 MNoVCW3 品系相关的死亡率不需要 LysM+ 细胞上的 CD300lf 表达，这突出表明 CD300lf 受体表达和先天免疫在体内调节 MNoV 细胞向性。
Noroviruses are a leading cause of gastrointestinal infection in humans and mice. Understanding human norovirus (HuNoV) cell tropism has important implications for our understanding of viral pathogenesis. Murine norovirus (MNoV) is extensively used as a surrogate model for HuNoV. We previously identified CD300lf as the receptor for MNoV. Here, we generated a Cd300lf conditional knockout (CD300lf(F/F)) mouse to elucidate the cell tropism of persistent and nonpersistent strains of murine norovirus. Using this mouse model, we demonstrated that Cd300lf expression on intestinal epithelial cells (IEC5), and on tuft cells in particular, is essential for transmission of the persistent MNoV strain CR6 (MNoVCR6) in vivo. In contrast, the nonpersistent MNoV strain CW3 (MNoVCW3) does not require CD300lf expression on IECs for infection. However, deletion of CD300lf in myelomonocytic cells (LysM Cre+) partially reduces CW3 viral load in lymphoid and intestinal tissues. Disruption of CD300lf expression on B cells (CD19 Cre), neutrophils (Mrp8 Cre), and dendritic cells (CD11c Cre) did not affect MNoVCW3 viral RNA levels. Finally, we show that the transcription factor STAT1, which is critical for the innate immune response, partially restricts the cell tropism of MNoVCW3 to LysM+ cells. Taken together, these data demonstrate that CD300lf expression on tuft cells is essential for MNoVCR6; that myelomonocytic cells are a major, but not exclusive, target cell of MNoVCW3; and that STAT1 signaling restricts the cellular tropism of MNoVCW3. This study provides the first genetic system for studying the cell type-specific role of CD300lf in norovirus pathogenesis.IMPORTANCE Human noroviruses (HuNoVs) are a leading cause of gastroenteritis resulting in up to 200,000 deaths each year. The receptor and cell tropism of HuNoV in immunocompetent humans are unclear. We use murine norovirus (MNoV) as a model for HuNoV. We recently identified CD300If as the sole physiologic receptor for MNoV. Here, we leverage this finding to generate a Cd300lf conditional knockout mouse to decipher the contributions of specific cell types to MNoV infection. We demonstrate that persistent MNoVCR6 requires CD300If expression on tuft cells. In contrast, multiple CD300lf+ cell types, dominated by myelomonocytic cells, are sufficient for nonpersistent MNoVCW3 infection. CD300lf expression on epithelial cells, B cells, neutrophils, and dendritic cells is not critical for MNoVCW3 infection. Mortality associated with the MNoVCW3 strain in Stat1(-/-) mice does not require CD300lf expression on LysM+ cells, highlighting that both CD300lf receptor expression and innate immunity regulate MNoV cell tropism in vivo.