Contributes to virulence by binding to the host IKBKB subunit of the IKK complex and preventing host NF-kappa-B activation in response to pro-inflammatory stimuli such as TNF-alpha or IL1B. Mechanistically, sterically hinders the direct contact between the kinase domains of IKBKB in the IKK complex containing IKBKB, CHUK/IKKA and NEMO (PubMed:29748387). Homodimers. Interaction with host IKBKB; this interaction inhibits host NF-kappa-B activation. Belongs to the orthopoxvirus B14 protein family.