Oncolytic Vaccinia Virus Armed With CLEC2A Enhances Antitumor Immunity via ROS-Autophagy Feedback Loop and Cytokine Activation.

Tumors often exhibit immunosuppressive microenvironments (TMEs) and present as immunologically "cold." Oncolytic viruses (OVs), particularly engineered vaccinia viruses (oncoVVs), are an encouraging therapy that directly lyses cancer cells and reprograms the TME. In this study, we evaluated the therapeutic potential of an oncolytic vaccinia virus expressing human C-type lectin domain family 2 member A (oncoVV-CLEC2A) in melanoma and ovarian cancer cells. OncoVV-CLEC2A elevated reactive oxygen species (ROS) levels, suppressed Nrf2-mediated antioxidant responses, and triggered autophagy. These changes promoted cytokine production (IL-6, IFN-α/β/γ, TNF-α) via activation of AP-1 and IRF3/7. In a B16-F10 melanoma model, oncoVV-CLEC2A increased serum levels of IFN-γ, accompanied by augmented infiltration of CD8+ T cells and activation of NK cells. Taken together, oncoVV-CLEC2A reshapes the TME by intensifying oxidative stress and autophagic activity, effectively turning "cold" tumors "hot." Notably, the mutual reinforcement between ROS production and autophagy activation not only enhances viral replication but also triggers cytokine-mediated immunity.