Formation of empty B19 parvovirus capsids by the truncated minor capsid protein.

We previously reported that empty capsids of B19 parvovirus were formed by the major capsid protein (VP2) alone expressed in a baculovirus system, but the minor capsid protein (VP1), longer by 227 amino acids, alone did not form empty capsids. We report here further investigations of the constraints on capsid formation by truncated versions of VP1. Studies were performed with recombinant baculoviruses expressed in Sf9 cells. Severely shortened VP1, extended beyond the VP2 core sequence by about 70 amino acids of the unique region, formed capsids normal in appearance; longer versions of VP1 also formed capsids but did so progressively less efficiently and produced capsids of more markedly dysmorphic appearance as the VP1-unique region was lengthened.