STING Restricts EV-A71 Infection by Regulating T Cell Development and Enhancing Immune Cell Effector Function.

Previous studies have reported that Enterovirus A71 (EV-A71) infection could activate STING-related signaling pathways in vitro, but the role of STING in EV-A71 infection in vivo and the associated immune regulatory mechanisms remain unclear. Here, we used the STING-specific agonist diABZI to activate STING and STING-knockout mice to jointly study the role and mechanism of regulating STING on EV-A71 infection in vivo. The results showed that activating STING could inhibit the in vivo replication of EV-A71, alleviate clinical symptoms in infected mice, and increase the survival rate. Conversely, STING knockout significantly promoted viral replication in vivo and increased the lethality and severity of EV-A71 infection. Mechanistic studies further revealed that STING activation exerts its antiviral effects by stimulating interferon signaling pathways, upregulating the expression of interferon-stimulated genes (ISGs). Additionally, STING activation also modulated the serum cytokine response profile. Moreover, STING activation drove the expansion of diverse immune cell populations, including T cells, natural killer (NK) cells and myeloid cells. In contrast, STING knockout not only reduced the proportion of thymic T cells and impeded T cell developmental progression from double-positive (DP) to single-positive (SP) stages, but also impaired the effector functions of CD8+ T cells and NK cells during viral infection. In summary, this study demonstrates that STING activation effectively suppresses EV-A71 replication and mitigates infection symptoms by modulating immune and inflammatory responses. These findings provide a foundational framework for understanding how STING coordinates antiviral immunity and inform future investigations into STING-targeted therapies for viral infections.