Upon viral infection, the cGAS-STING axis is pivotal for initiating type I interferon (IFN) production against DNA viruses. In this study, we identified Annexin A2 (ANXA2) as a novel and potent negative regulator of this antiviral pathway. Overexpression of ANXA2 inhibits herpes simplex virus-1 (HSV-1)-induced IFN-β production, thereby promoting viral replication, whereas ANXA2 deficiency enhances IFN responses and restricts HSV-1 replication. Mechanistically, ANXA2 operates through a dual mechanism. First, it interacts with the transmembrane domain of STING and inhibits its agonist-triggered translocation from the endoplasmic reticulum to the Golgi apparatus, a step essential for STING activation. Second, ANXA2 binds to the nuclear export signal of IRF3, competing with the kinases TBK1 and IKKε for IRF3 interaction. This disrupts the formation of the TBK1-IKKε-IRF3 complex, thereby suppressing IRF3 phosphorylation and nuclear translocation. This function is independent of its canonical binding partner S100A10 but requires ANXA2's calcium-binding capacity. Crucially, in vivo studies using Anxa2⁻/⁻ mice confirmed that ANXA2 deficiency enhances type I IFN production, limits viral replication, and improves survival following HSV-1 challenge. Collectively, our findings unveil a multifaceted role for ANXA2 in dampening host antiviral immunity by targeting both the STING trafficking and the TBK1/IKKε-IRF3 activation steps, highlighting it as a potential target for immunomodulatory antiviral strategies.

Importance: The cGAS-STING axis is essential for host resistance to DNA virus infections by regulating type I interferon (IFN) production. This study is significant because it identifies Annexin A2 (ANXA2) as a previously unrecognized and potent negative regulator of the host antiviral response against DNA viruses like herpes simplex virus-1. The findings demonstrate that ANXA2 suppresses type I interferon production through a dual mechanism: by inhibiting the critical transport of STING to the Golgi apparatus and by disrupting the kinase activity of TBK1/IKKε required for IRF3 activation. This role is independent of its known partner S100A10, revealing a novel function for ANXA2. The validation in knockout mice, which showed enhanced IFN production and restricted viral replication, confirms its physiological importance in vivo. By pinpointing ANXA2 as a key inhibitor of the cGAS-STING pathway, this research not only advances our understanding of immune regulation but also identifies ANXA2 as a potential therapeutic target for modulating antiviral defenses.

Keywords: Annexin A2; HSV-1; S100A10; cGAS-STING; transport of STING.