Department of Microbiology and Immunology, Bluemle Life Science Building, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
J Virol. 2023 Feb 28;97(2):e0194522. doi: 10.1128/jvi.01945-22. Epub 2023 Jan 18.
Receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL) are proteins that are critical for necroptosis, a mechanism of programmed cell death that is both activated when apoptosis is inhibited and thought to be antiviral. Here, we investigated the role of RIPK3 and MLKL in controlling the Orthopoxvirus ectromelia virus (ECTV), a natural pathogen of the mouse. We found that C57BL/6 (B6) mice deficient in RIPK3 () or MLKL () were as susceptible as wild-type (WT) B6 mice to ECTV lethality after low-dose intraperitoneal infection and were as resistant as WT B6 mice after ECTV infection through the natural footpad route. Additionally, after footpad infection, mice, but not mice, endured lower viral titers than WT mice in the draining lymph node (dLN) at three days postinfection and in the spleen or in the liver at seven days postinfection. Despite the improved viral control, mice did not differ from WT mice in the expression of interferons or interferon-stimulated genes or in the recruitment of natural killer (NK) cells and inflammatory monocytes (iMOs) to the dLN. Additionally, the CD8 T-cell responses in and WT mice were similar, even though in the dLNs of mice, professional antigen-presenting cells were more heavily infected. Finally, the histopathology in the livers of and WT mice at 7 dpi did not differ. Thus, the mechanism of the increased virus control by mice remains to be defined. The molecules RIPK3 and MLKL are required for necroptotic cell death, which is widely thought of as an antiviral mechanism. Here we show that C57BL/6 (B6) mice deficient in RIPK3 or MLKL are as susceptible as WT B6 mice to ECTV lethality after a low-dose intraperitoneal infection and are as resistant as WT B6 mice after ECTV infection through the natural footpad route. Mice deficient in MLKL are more efficient than WT mice at controlling virus loads in various organs. This improved viral control is not due to enhanced interferon, natural killer cell, or CD8 T-cell responses. Overall, the data indicate that deficiencies in the molecules that are critical to necroptosis do not necessarily result in worse outcomes following viral infection and may improve virus control.
受体相互作用蛋白激酶 3 (RIPK3) 和混合谱系激酶结构域样伪激酶 (MLKL) 是对细胞程序性坏死至关重要的蛋白，细胞程序性坏死是一种凋亡被抑制时被激活的细胞死亡机制，被认为具有抗病毒作用。在这里，我们研究了 RIPK3 和 MLKL 在控制正痘病毒细小病毒 (ECTV) 中的作用，ECTV 是小鼠的一种天然病原体。我们发现，在低剂量腹腔感染后，缺乏 RIPK3 () 或 MLKL () 的 C57BL/6 (B6) 小鼠与野生型 (WT) B6 小鼠一样容易感染 ECTV 致死，而通过自然足底途径感染 ECTV 后，它们与 WT B6 小鼠一样具有抗性。此外，在足底感染后，与 WT 小鼠相比，在感染后三天的引流淋巴结 (dLN) 以及感染后七天的脾脏或肝脏中， 小鼠的病毒滴度较低，但 小鼠并非如此。尽管病毒控制得到改善，但 小鼠在干扰素或干扰素刺激基因的表达、自然杀伤 (NK) 细胞和炎症单核细胞 (iMO) 向 dLN 的募集方面与 WT 小鼠没有差异。此外， 小鼠和 WT 小鼠的 CD8 T 细胞反应相似，尽管在 小鼠的 dLN 中，专业抗原呈递细胞受到更严重的感染。最后，在 7 dpi 时， 小鼠和 WT 小鼠的肝脏组织病理学没有差异。因此， 小鼠增加病毒控制的机制仍有待确定。分子 RIPK3 和 MLKL 是细胞坏死性细胞死亡所必需的，而细胞坏死性细胞死亡被广泛认为是一种抗病毒机制。在这里，我们表明，缺乏 RIPK3 或 MLKL 的 C57BL/6 (B6) 小鼠与 WT B6 小鼠一样容易在低剂量腹腔感染后发生 ECTV 致死，并且在通过自然足底途径感染 ECTV 后与 WT B6 小鼠一样具有抗性。缺乏 MLKL 的小鼠比 WT 小鼠更有效地控制各种器官中的病毒载量。这种改善的病毒控制不是由于增强的干扰素、自然杀伤细胞或 CD8 T 细胞反应。总体而言，数据表明，对坏死性细胞死亡至关重要的分子的缺乏不一定会导致病毒感染后出现更糟糕的结果，并且可能会改善病毒控制。
