Late protein which probably participates in disulfide bond formation by functioning as a thiol-disulfide transfer protein between membrane-associated E10 and G4. The complete pathway for formation of disulfide bonds in intracellular virion membrane proteins sequentially involves oxidation of E10, A2.5 and G4. Interacts with sulfhydryl oxidase E10; this interaction involves formation of a transient disulfide-bonded intermediate, allowing disulfide bond transfer. Interacts with G4; this interaction involves formation of a transient disulfide-bonded intermediate, allowing disulfide bond transfer. Expressed in the late phase of the viral replicative cycle. Belongs to the chordopoxvirinae A2.5 family.