Neutralization of SARS-CoV-2 Omicron subvariant BA.2.87.1

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• A novel Omicron subvariant, BA.2.87.1, has emerged with extensive mutations in the Spike protein.
• Over 30 amino acid substitutions distinguish BA.2.87.1 from previously identified variants like BA.2, BA.5, XBB.1.5, and JN.1.
• A notable characteristic of BA.2.87.1 is the concentration of mutations within the N-terminal domain (NTD) of the Spike protein, differing from mutations predominantly in the receptor-binding domain (RBD) of other variants.

Purpose of the Study:

• To investigate the impact of BA.2.87.1's unique mutational profile on neutralizing antibody (NAb) responses.
• To compare the immunogenicity of BA.2.87.1 against established SARS-CoV-2 variants.
• To assess the effectiveness of XBB.1.5 mRNA vaccination in eliciting NAbs against BA.2.87.1.

Main Methods:

• Analysis of Spike protein mutations in BA.2.87.1 compared to other Omicron subvariants.
• Measurement of neutralizing antibody titers against BA.2.87.1.
• Evaluation of antibody responses following XBB.1.5 mRNA vaccination.

Main Results:

• Neutralizing antibody responses elicited by BA.2.87.1 were found to be lower compared to the BA.2 subvariant.
• However, NAb responses to BA.2.87.1 were observed to be higher than those against the JN.1 subvariant.
• Administration of an XBB.1.5 mRNA booster significantly elevated NAb titers against all tested variants, including BA.2.87.1.

Conclusions:

• BA.2.87.1 does not appear to represent a significant antibody escape variant relative to currently circulating SARS-CoV-2 strains.
• The findings suggest that existing immunity, particularly after XBB.1.5 mRNA boosting, may offer cross-protection against BA.2.87.1.
• The unique mutation pattern in the NTD of BA.2.87.1 warrants further investigation into its specific immunological implications.