Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
Faculty of Veterinary Medicine, Department of Pathology & Clinical Pathology, Assiut University, Assiut, Egypt.
PLoS One. 2023 Feb 3;18(2):e0279843. doi: 10.1371/journal.pone.0279843. eCollection 2023.
Sapoviruses belonging to the genus Sapovirus within the family Caliciviridae are commonly responsible for severe acute gastroenteritis in both humans and animals. Caliciviruses are known to induce intrinsic apoptosis in vitro and in vivo, however, calicivirus-induced necroptosis remains to be fully elucidated. Here, we demonstrate that infection of porcine kidney LLC-PK cells with porcine sapovirus (PSaV) Cowden strain as a representative of caliciviruses induces receptor-interacting protein kinase 1 (RIPK1)-dependent necroptosis and acts as proviral compared to the antiviral function of PSaV-induced apoptosis. Infection of LLC-PK cells with PSaV Cowden strain showed that the interaction of phosphorylated RIPK1 (pRIPK1) with RIPK3 (pRIPK3), mixed lineage kinase domain-like protein (pMLKL) increased in a time-dependent manner, indicating induction of PSaV-induced RIPK1-dependent necroptosis. Interfering of PSaV-infected cells with each necroptotic molecule (RIPK1, RIPK3, or MLKL) by treatment with each specific chemical inhibitor or knockdown with each specific siRNA significantly reduced replication of PSaV but increased apoptosis and cell viability, implying proviral action of PSaV-induced necroptosis. In contrast, treatment of PSaV-infected cells with pan-caspase inhibitor Z-VAD-FMK increased PSaV replication and necroptosis, indicating an antiviral action of PSaV-induced apoptosis. These results suggest that PSaV-induced RIPK1-dependent necroptosis and apoptosis‒which have proviral and antiviral effects, respectively‒counterbalanced each other in virus-infected cells. Our study contributes to understanding the nature of PSaV-induced necroptosis and apoptosis and will aid in developing efficient and affordable therapies against PSaV and other calicivirus infections.
杯状病毒科杯状病毒属的肠道病毒通常可引起人和动物的急性严重胃肠炎。已知杯状病毒在体外和体内诱导细胞凋亡，但杯状病毒诱导的坏死性凋亡仍有待充分阐明。在这里，我们证明猪肾 LLC-PK 细胞感染猪肠道病毒（PSaV）考登株作为杯状病毒的代表，可诱导受体相互作用蛋白激酶 1（RIPK1）依赖性坏死性凋亡，并具有促病毒作用，而不是 PSaV 诱导的细胞凋亡的抗病毒作用。PSaV Cowden 株感染 LLC-PK 细胞显示，磷酸化 RIPK1（pRIPK1）与 RIPK3（pRIPK3）、混合谱系激酶结构域样蛋白（pMLKL）的相互作用呈时间依赖性增加，表明诱导了 PSaV 诱导的 RIPK1 依赖性坏死性凋亡。用每种特定化学抑制剂处理或用每种特定 siRNA 敲低 PSaV 感染细胞中的每种坏死性凋亡分子（RIPK1、RIPK3 或 MLKL），可显著降低 PSaV 的复制，但增加细胞凋亡和细胞活力，提示 PSaV 诱导的坏死性凋亡具有促病毒作用。相比之下，用泛半胱天冬酶抑制剂 Z-VAD-FMK 处理 PSaV 感染细胞可增加 PSaV 复制和坏死性凋亡，表明 PSaV 诱导的细胞凋亡具有抗病毒作用。这些结果表明，PSaV 诱导的 RIPK1 依赖性坏死性凋亡和细胞凋亡（分别具有促病毒和抗病毒作用）在病毒感染细胞中相互平衡。我们的研究有助于了解 PSaV 诱导的坏死性凋亡和细胞凋亡的性质，并将有助于开发针对 PSaV 和其他杯状病毒感染的有效且经济实惠的疗法。
