Together with the penton and the other minor capsid proteins (M1249L, p49), forms a complicated network immediately below the outer capsid shell, stabilizing the whole capsid (PubMed:31624094). Three copies of p17 encircle each p72 capsomer in the inner capsid shell, anchoring p72 capsomers on the inner membrane (PubMed:31624094). Required for the assembly of the capsid and icosahedral morphogenesis (PubMed:20504920). Interacts with the minor capsid protein M1249L and with the hexon capsid protein p72 capsomers; these interactions form a rigid zipper structure that stabilizes the capsomers. Found in the inner envelope of the virus. Expressed in the late phase of the viral replicative cycle. Belongs to the asfivirus minor capsid protein p17 family.