Fig. 7: ORFV induces GSDME-mediated pyroptosis and activates antitumor immunity.

We can generate different ORFV recombinants with one or two genes deletion, which are armed with the EGFP gene for imaging. WT ORFV and ORFV recombinants are able to trigger GSDME-mediated pyroptosis in tumor cell lines, in vivo tumor tissues, and ex vivo human colon cancer tissues. ORFV can pre-stabilize GSDME protein levels in GSDME-low tumor cells through decreasing ubiquitination of GSDME, which was followed by GSDME cleavage and pyroptotic cell death. ORFV-triggered GSDME-mediated tumor pyroptosis recruits CTLs into the tumor microenvironment, which is accompanied by the release of inflammatory mediators. This remodels the tumor microenvironment and turns immunologically “cold” tumors into “hot” tumors, thereby sensitizes these tumors to checkpoint blockade. While the immunologically “cold” tumors are not able to respond to checkpoint blockade.