SPR Analysis of Monkeypox Proteins A29L and E8L Glycan Interaction and Inhibition by Marine-Derived Glycans

The global resurgence of mpox has established monkeypox virus (MPXV), comprising Clades I and II, as a significant public health threat. Studies of homologous vaccinia virus proteins indicate that cell-surface glycosaminoglycans (GAGs), including heparan sulfate (HS) and chondroitin sulfate (CS), facilitate viral attachment and entry. However, direct interactions between GAGs and MPXV surface proteins A29L/E8L remain poorly characterized. Using surface plasmon resonance (SPR), we quantified the apparent binding affinities of A29L (Clade I KD = 0.8 ± 0.3 nM) and E8L (Clade I KD = 1.2 ± 0.2 nM; Clade II KD = 1.6 ± 0.1 nM) for heparin, a common HS analog. We also quantified E8L apparent binding affinities to CS-A (Clade I KD = 0.4 ± 0.2 nM; Clade II KD = 0.65 ± 0.06 nM) and CS-E (KD = 0.6 ± 0.1 nM; Clade II KD = 0.70 ± 0.08 nM). We further determined that Clade I A29L and E8L preferentially recognized long-chain fully sulfated or N-sulfated heparin. Lastly, we determined a small library of marine-derived sulfated glycans (MSGs) as effective inhibitors for the Clade I E8L and A29L protein-GAG interface. These findings establish previously uncharacterized binding interactions and identify MSGs as potential candidates for anti-mpox drug development.