Recombinant Human parvovirus B19 Minor capsid protein VP1, partial

Capsid protein self-assembles to form an icosahedral capsid with a T=1 symmetry, about 20 nm in diameter, and consisting of 60 copies of two size variants of the capsid proteins, VP1 and VP2, which differ by the presence of an N-terminal extension in the minor protein VP1. The capsid encapsulates the genomic ssDNA. Binds to erythroid progenitor cells expressing high levels of P antigen and uses host ITGA5-ITGB1 and XRCC5/Ku80 autoantigen as coreceptors on the cell surface to provide virion attachment to target cell. This attachment induces virion internalization predominantly through clathrin-dependent endocytosis. Binding to the host receptors also induces capsid rearrangements leading to surface exposure of VP1 N-terminus, specifically its phospholipase A2-like region. The additional N-terminal region of isoform Minor capsid protein VP1, called VP1u, may serve as a lipolytic enzyme to breach the endosomal membrane during entry into host cell and might contribute to virus transport to the nucleus.