BioLayer interferometry (BLI) binding studies with wildtype gp42.

Binding kinetics were measured with the Octet RED96 instrument (ForteBio, Pall Corporation) using wildtype (wt) gp42 protein. (A) Biotinylated EBV gHgL was immobilized on streptavidin (SA) biosensor tips and incubated over a range of concentrations (0.4–100 nM) of soluble wt gp42. (B) Biotinylated HLA-DQ2 (CLIP1) was immobilized on streptavidin biosensor tips and incubated over a range of concentrations (2–1200 nM) of soluble wt gp42. (C) Immobilized HLA-DQ2 (CLIP1) was incubated with increasing concentrations of preformed gHgL/gp42 complexes (30–800 nM). Data was fit globally to different binding schemes corresponding to a 1∶1 langmuir binding isotherm (A) and a 2∶1 heterogeneous ligand binding model (B and C). (D) Steady state analysis of the gHgL/gp42 binding to HLA-DQ2 shown in C for equilibrium KD determination. Fitted kinetic and equilibrium binding constants are collected in Table 2.