The Veesler lab at University of Washington published a new study in Cell revealing the mechanism of neutralization of two antibodies against SARS and MERS coronavirus spikes.
The team used cryo electron microscopy and mass spectrometry to study the antibodies in complex with spike proteins at near-atomic resolution and profile the composition of the viral glycan shields. The reconstructions revealed that the antibodies interact with the receptor binding domains of the spike proteins. The antibody that targets the SARS spike protein functionally mimics receptor binding by triggering a premature transition to the post-fusion conformation.
Glycoproteomics experiments revealed a very complex and heterogeneous pattern of glycosylation of the viral spikes. Some glycans are in direct contact with the neutralizing antibodies. Such a high degree of variability in glycosylation is thought to complicate antigen recognition by the host immune system.