SQSTM1/p62-mediated autophagy and antioxidation contribute to white spot syndrome virus pathogenesis in shrimp

Abstract

Selective macroautophagy/autophagy, mediated by selective autophagy receptors (SARs), targets cellular cargo and pathogenic proteins for lysosomal degradation. While crucial in antiviral immunity, viruses have evolved strategies to evade or exploit selective autophagy. Despite extensive studies in vertebrates, the role of selective autophagy in crustaceans during viral infections remains largely unexplored. This study investigates the molecular mechanism of Penaeus vannamei selective autophagy receptor SQSTM1/p62 (PvSQSTM1) in the shrimp immune response to white spot syndrome virus (WSSV) infection. We demonstrated that WSSV infection activates PvSQSTM1-mediated selective autophagy in hemocytes. During infection, PvSQSTM1 was predominantly localized in the cytoplasm, with partial nuclear localization. PvSQSTM1 silencing reduced viral load and increased shrimp survival by suppressing autophagic activity. PvSQSTM1 dynamically interacted with the major WSSV envelope protein VP28 during early infection and facilitated WSSV encapsulation within autophagosomes. Apart from selective autophagy, PvSQSTM1 was involved in antioxidant resistance mechanisms, as shown by its direct binding to PvKEAP1, an adaptor of the SQSTM1-KEAP1-NFE2L2/Nrf2 pathway. The reduced expression of downstream genes in the SQSTM1-KEAP1-NFE2L2/Nrf2 pathway was observed in PvSQSTM1-silenced shrimp infected with WSSV, leading to increased H<inf>2</inf>O<inf>2</inf> levels in hemocytes. Together, these findings suggest that PvSQSTM1-mediated autophagy facilitates viral encapsulation within autophagosomes and regulates the KEAP1-NFE2L2/Nrf2 antioxidant pathway to suppress ROS levels. This mechanism potentially allows the virus to evade the host’s immune system and establish a successful infection. This work expands our understanding of host-virus interactions, highlighting the contribution of PvSQSTM1 to WSSV pathogenesis. Abbreviation: AP-MS: affinity purification-mass spectrometry; ATG: autophagy related; hpi: h post-infection; LIR: LC3-interacting region; SARs: selective autophagy receptors; SQSTM1/p62: sequestosome 1; WSSV: white spot syndrome virus.