Membrane fusion and immune evasion by the spike protein of SARS-CoV-2 delta variant

The spike (S) protein of SARS-CoV-2 causes membrane fusion more efficiently than those of other variants even in the case of the low levels of cellular receptor ACE2. The S protein of many variants shows different rearrangement of N-terminal domain, but the receptor-binding domain is relatively conserved among strains. This emphasizes the importance of the N-terminal domain for the target of immunological therapy such as neutralizing antibody.