White Spot Syndrome Virus (WSSV) Inhibits Hippo Signaling and Activates Yki To Promote Its Infection in Penaeus vannamei

White spot syndrome virus (WSSV) is a serious threat to shrimp aquaculture, especially Pacific white shrimp, Penaeus vannamei, the most farmed shrimp in the world. Activation of the Hippo-Yki signaling pathway, characterized by the intracellular Hippo-Wts kinase cascade reactions and the phosphorylation and cytoplasmic retention of Yki, is widely involved in various life activities. The current work established the fundamental structure and signal transduction profile of the Hippo-Yki pathway in P. vannamei and further investigated its role in viral infection. We demonstrated that WSSV promoted the dephosphorylation and nuclear translocation of Yki, suggesting that Hippo signaling is impaired and Yki is activated after WSSV infection in shrimp. In vivo, Yki gene silencing suppressed WSSV infection, while Hippo and Wts silencing promoted it, indicating a positive role of Hippo signaling in antiviral response. Further analyses showed that Yki suppressed Dorsal pathway activation and inhibited hemocyte apoptosis in WSSV-infected shrimp, while Hippo and Wts showed opposite effects, which contributed to the role of Hippo signaling in WSSV infection. Therefore, the current study suggests that WSSV annexes Yki to favor its infection in shrimp by inhibiting Hippo signaling. IMPORTANCE White spot syndrome virus (WSSV) is one of the most harmful viral pathogens to shrimp. The pathological mechanism of WSSV infection remains unclear to date. The Hippo-Yki signaling pathway is important for various biological processes and is extensively involved in mammalian immunity, but little is known about its role in infectious diseases in invertebrates. Based on revealing the fundamental structure of the shrimp Hippo pathway, this study investigated its implication in the pathogenesis of WSSV disease. We demonstrated that WSSV enhanced Yki activation by inhibiting Hippo signaling in shrimp. The activated Yki promoted WSSV infection by inhibiting hemocyte apoptosis and suppressing the activation of Dorsal, an NF-κB family member in shrimp that is critical for regulating antiviral response. Therefore, this study suggests that WSSV can hijack the Hippo-Yki signaling pathway to favor its infection in shrimp.