Interactions of JCPyV VP1 with the GM1 glycan reduces virus infection. (A) VP1 engages the GM1 glycan in solution in a manner similar to that for SV40 VP1. From top to bottom: NMR spectrum of the GM1 glycan and STD NMR difference spectra of WT3 VP1, Mad-1 VP1, and SV40 VP1 with GM1 glycan (50-fold molecular excess). (B) GM1 glycan engagement by SV40, Mad-1, and WT3 VP1. GM1 glycans are colored blue, pink, or green for SV40 (PDB 3BWR), Mad-1, and WT3, respectively. The Glc residue of GM1, which is not in contact with VP1, is not shown for clarity. (C) Pretreatment of Mad-1 or Mad-1/WT3C virus with LSTc or GM1 glycan reduces infection. Data represent the average number of infected cells per visual field (10×) for 4 fields of view of triplicate samples. Error bars indicate standard deviations (SD).