College of Veterinary Medicine, Northwest A&F University, Yangling, China.
Engineering Research Center of Efficient New Vaccines for Animals, Ministry of Education, Yangling, China.
Vet Res. 2024 Nov 29;55(1):156. doi: 10.1186/s13567-024-01410-x.
Porcine parvovirus (PPV) infection induces germ cell death, leading to reproductive disorders in first-pregnant sows. Porcine placental trophoblast cells (PTCs) are the major target of PPV, and we have previously found that PPV infection leads to the death of PTCs by a non-apoptotic process, which may be related to PPV pathogenicity. The Z-nucleic acid-binding protein 1 (ZBP1) is often activated after virus invasion and mediates subsequent cell death. Here, we found that PPV infection induced ZBP1-mediated necroptosis of porcine PTCs in the presence of the apoptosis inhibitor, AC-DEVD-CHO. ZBP1 expression was upregulated during PPV infection, and ZBP1 knockout or RNA interference significantly reduced its expression along with the PPV-induced necroptosis. We discovered that RIPK3 and MLKL, but not Caspase-8, were involved in downstream signaling of ZBP1 during PPV infection; the phosphorylation levels of RIPK3 and MLKL were enhanced, but Caspase-8 was not significantly cleaved. The knockout of RIPK3 and MLKL significantly reduced the PPV infection-induced necroptosis of porcine PTCs. RIPK3 knockout did not affect the PPV infection-induced upregulation of ZBP1 expression, but blocked the activation of MLKL. MLKL knockout did not affect the upregulation of ZBP1 expression and RIPK3 phosphorylation during PPV infection. UV-inactivated PPV induced significantly less necroptosis of porcine PTCs than non-irradiated PPV. A PPV strain with a mutation in the translation initiation codon was still able to induce necroptosis of PTCs through the ZBP1/RIPK3/MLKL pathway. These results provide new insights into the pathogenic mechanism of PPV infection and suggest that PPV infection of porcine PTCs induces necroptosis through the viral DNA-dependent ZBP1/RIPK3/MLKL pathway.
猪细小病毒（PPV）感染诱导生殖细胞死亡，导致初产母猪繁殖障碍。猪胎盘滋养层细胞（PTCs）是 PPV 的主要靶细胞，我们之前发现 PPV 感染通过非凋亡过程导致 PTCs 死亡，这可能与 PPV 的致病性有关。Z 核酸结合蛋白 1（ZBP1）在病毒入侵后常被激活，并介导随后的细胞死亡。在这里，我们发现在凋亡抑制剂 AC-DEVD-CHO 的存在下，PPV 感染诱导了猪 PTCs 的 ZBP1 介导的坏死性细胞死亡。在 PPV 感染过程中，ZBP1 的表达上调，ZBP1 敲除或 RNA 干扰显著降低了其表达以及 PPV 诱导的坏死性细胞死亡。我们发现，在 PPV 感染过程中，RIPK3 和 MLKL，但不是 Caspase-8，参与了 ZBP1 的下游信号转导；RIPK3 和 MLKL 的磷酸化水平增强，但 Caspase-8 没有明显被切割。RIPK3 和 MLKL 的敲除显著降低了 PPV 感染诱导的猪 PTCs 的坏死性细胞死亡。RIPK3 敲除不影响 PPV 感染诱导的 ZBP1 表达上调，但阻断了 MLKL 的激活。MLKL 敲除不影响 PPV 感染过程中 ZBP1 表达和 RIPK3 磷酸化的上调。与未照射的 PPV 相比，紫外线灭活的 PPV 诱导的猪 PTCs 坏死性细胞死亡明显减少。翻译起始密码子突变的 PPV 株仍能通过 ZBP1/RIPK3/MLKL 途径诱导 PTCs 的坏死性细胞死亡。这些结果为 PPV 感染的致病机制提供了新的见解，并表明 PPV 感染猪 PTCs 通过病毒 DNA 依赖性 ZBP1/RIPK3/MLKL 途径诱导坏死性细胞死亡。
