VP4 self-assembles to form, together with capsid protein VP10, an icosahedral caspid of 87 nm in diameter, with a T=43 symmetry and composed of 420 hexamers and 12 pentamers (PubMed:31636205). VP4 proteins arrange into hexons, while VP10 proteins form the pentameric densities located at the 5-fold axes in the virion (PubMed:31636205). The stoichiometry of VP4:VP10 is 42:1 (PubMed:31636205).