Activation of ZBP1/RIPK3/MLKL-Dependent Necroptosis by Pseudorabies Virus Restricts Viral Infection in BV2 Microglia...

Pseudorabies (PR) virus (PRV), also known as suid herpesvirus 1, is an alphaherpesvirus that causes huge economic losses in the global swine industry. Necroptosis, a caspase-independent programmed cell death, has been demonstrated to play an important role in regulating viral infections. Here, we showed that PRV infection triggered receptor-interacting protein (RIP) kinase (RIPK) 3/mixed lineage kinasedomain-like (MLKL)-dependent necroptosis in BV2 microglial cells. Mechanistically, PRV infection induced the formation of Z-DNA and upregulated the expression of Z-nucleic acid-binding protein 1 (ZBP1), leading to ZBP1-RIPK3 interaction that triggered the RIPK3/MLKL-dependent necroptosis pathway. Additionally, both RNA interference and protein overexpression experiments demonstrated that RIPK3 and MLKL independently restricted PRV infection in BV2 microglial cells. The underlying mechanism lay in the fact that RIPK3 and MLKL can independently enhance the interferon (IFN)-β signaling pathway. Similarly, pharmacological inhibition of RIPK3 and MLKL using GW806742X and UH15-38 promoted PRV infection in BV2 microglial cells; however, this treatment did not affect IFN-β pathway activation. Taken together, our study elucidated the molecular mechanism of ZBP1/RIPK3/MLKL-dependent necroptosis activation during PRV infection and revealed that necroptosis signaling exerted anti-PRV effects in BV2 microglia cells. These findings provided novel insights into the antiviral defense mechanisms of microglia in the central nervous system (CNS) and suggested that targeting necroptosis signaling may offer a therapeutic strategy for controlling PRV infection.