JCV VP1

The polyomavirus capsid consists of 360 copies of VP1 arranged into 72 pentamers called "capsomers" in a T = 7 d icosahedral configuration. The internal face of each capsomer associates with a single copy of a minor capsid protein, VP2 or VP3. The secondary structure of VP1 is organized as antiparallel β strands (BIDG and CHEF) which form a structure commonly referred to as a jelly roll. The loops connecting several of these strands (BC, DE, EF, and HI) form the majority of the external surface of the capsid. This surface forms a depression which is responsible for receptor binding. Polyomaviruses bind to sialyated glycans, with strains within each polyomavirus family varying in recognition of sialic acids having different linkages to glycolipid and/or glycoprotein backbones. The canonical receptor for JCPyV is the sialylated oligosaccharide lactoseries tetrasaccharide c (LSTc), which interacts with residues in the BC and HI loops of VP1. VP1 mutations disrupting the interactions with LSTc have profound effects on viral infectivity. After receptor binding, JCPyV entry is facilitated by the 5-HT2 serotonin receptor.