Wu Pan-Xue, Yang Wen-Ping, Feng Tao, Zhang Jing, Zhu Guo-Qiang, Du Xu-Guang, Ru Yi, Zhao Yao-Feng, Wu Sen, Li Dan, Zheng Hai-Xue
State Key Laboratory of Animal Biotech Breeding College of Biological Sciences, National Engineering Laboratory for Animal Breeding, Frontiers Science Center for Molecular Design Breeding, China Agricultural University, Beijing, China.
State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China.
J Virol. 2025 Apr 15;99(4):e0208024. doi: 10.1128/jvi.02080-24. Epub 2025 Mar 26.
African swine fever virus (ASFV) is the pathogen of African swine fever (ASF), and its infection causes a lethal disease in pigs, with severe pathological lesions. These changes indicate excessive inflammatory responses in infected pigs, which is the main cause of death, but the ASFV proteins worked in this physiological process and the mechanisms underlying ASFV-induced inflammation remain unclear. Here, we identify that viral I177L works in these inflammatory responses. Mechanistically, I177L facilitates TRAF6 ubiquitination that enhances its binding to TAK1, which promotes TAK1 ubiquitination and phosphorylation. These processes depend on the E3 ubiquitin ligase activity of TRAF6. The upregulation of I177L to TRAF6-TAK1 interaction and TAK1 activation is responsible for I177L's activated effect on the NF-κB signaling pathway. Additionally, I177L promotes assembly of the NLRP3 inflammasome and ASC oligomerization, thus leading to the activation of the NLRP3 inflammasome and the production and secretion of mature IL-1β. TAK1 inhibition efficiently reverses ASFV-activated NF-κB signaling and inflammatory responses and suppresses ASFV replication. Furthermore, I177L-deficient ASFV induces milder inflammatory responses in pigs compared with parental ASFV, which still protects pigs against ASFV challenge. The finding confirms ASFV I177L as an important proinflammatory protein and and reveals a key mechanism underlying ASFV-mediated inflammatory responses for the first time, which enriches our knowledge of the complex ASFV, thus benefiting our understanding of the interplay between ASFV infection and the host's inflammatory responses.IMPORTANCEAfrican swine fever (ASF) is a devastating viral disease in pigs, and excessive inflammatory responses induced by ASFV mainly cause death. Thus, the study of the proinflammatory virulent proteins and the detailed mechanisms are important to ASF control. Here, I177L was demonstrated to be an essential protein in ASFV-mediated inflammation, which performs by simultaneously activating the NF-κB signaling and the NLRP3 inflammasome. The finding elucidates the molecular mechanism underlying ASFV-activated inflammatory responses for the first time. It provides a theoretical foundation for reducing the high mortality caused by excessive inflammation and opens new avenues for small-molecule drug development and vaccine design targeting ASFV.
非洲猪瘟病毒（ASFV）是非洲猪瘟（ASF）的病原体，其感染会在猪身上引发致死性疾病，并伴有严重的病理损伤。这些变化表明受感染猪体内存在过度的炎症反应，这是导致死亡的主要原因，但ASFV蛋白在这一生理过程中的作用以及ASFV诱导炎症的机制仍不清楚。在此，我们确定病毒I177L在这些炎症反应中发挥作用。从机制上讲，I177L促进TRAF6泛素化，增强其与TAK1的结合，进而促进TAK1的泛素化和磷酸化。这些过程依赖于TRAF6的E3泛素连接酶活性。I177L对TRAF6-TAK1相互作用和TAK1激活的上调作用，是其对NF-κB信号通路激活作用的原因。此外，I177L促进NLRP3炎性小体的组装和ASC寡聚化，从而导致NLRP3炎性小体的激活以及成熟IL-1β的产生和分泌。抑制TAK1可有效逆转ASFV激活的NF-κB信号传导和炎症反应，并抑制ASFV复制。此外，与亲本ASFV相比，缺乏I177L的ASFV在猪体内诱导的炎症反应较轻，且仍能保护猪免受ASFV攻击。这一发现证实ASFV I177L是一种重要的促炎蛋白，并首次揭示了ASFV介导炎症反应的关键机制，丰富了我们对复杂的ASFV的认识，从而有助于我们理解ASFV感染与宿主炎症反应之间的相互作用。
非洲猪瘟（ASF）是猪的一种毁灭性病毒性疾病，ASFV诱导的过度炎症反应是导致死亡的主要原因。因此，研究促炎毒力蛋白及其详细机制对ASF防控至关重要。在此，I177L被证明是ASFV介导炎症中的一种必需蛋白，它通过同时激活NF-κB信号通路和NLRP3炎性小体发挥作用。这一发现首次阐明了ASFV激活炎症反应的分子机制。它为降低过度炎症导致的高死亡率提供了理论基础，并为针对ASFV的小分子药物开发和疫苗设计开辟了新途径。
