Plays a role in evading host innate immune response by inhibiting host inflammasome activation. Interacts with and inhibits NLR-mediated interleukin-1 beta/IL1B production in infected cells. At the host mitochondria, interacts with the BH3 domain of host BAK and prevents BAK from binding active BAX. In turn, host apoptosis is inhibited. Homodimer. Interacts with host pro-apoptotic protein BCL2L11 (via BH3 domain). Interacts with host NLRP1 (PubMed:23603272). Interacts with host BAK (PubMed:16439990). Belongs to the poxviridae F1 protein family.