Receptor binding mechanism and immune evasion capacity of SARS-CoV-2 BQ.1.1 lineage.

The global spread of COVID-19 remains a significant threat to human health. The SARS-CoV-2 BQ.1.1 lineage, including BA.5.2, BF.7, BQ.1 and BQ.1.1, caused a new soaring of infection cases due to rapid transmission. However, the receptor binding mechanism and immune evasion capacity of these variants need to be explored further. Our study found that while the BA.5.2, BF.7 and BQ.1.1 variants pseudovirus had similar cell entry efficiency, the BF.7 and BQ.1.1 RBD bound to human ACE2 (hACE2) with a slightly stronger affinity than the BA.5.2 RBD. Structural analysis revealed R346T, K444T, and N460K mutations altered RBD-hACE2 binding interface details and surface electrostatic potential of BQ.1.1 RBD. Serum neutralization tests showed BQ.1.1 variant had stronger immune evasion capacity than BA.5.2 and BF.7 variants. Our findings illustrated the receptor binding mechanism and serological neutralization activity of the BA.5.2, BF.7 and BQ.1.1 variants, which verified the necessity for further antibody therapy optimization and vaccination development.