Omicron reduces host antibody response by lower B-cell antigenicity Omicron COVID19 SARSCoV2 CellReports PittTweet HebrewU TelAvivUni
By Dr. Liji Thomas, MDOct 4 2022Reviewed by Benedette Cuffari, M.Sc. Since the onset of the coronavirus disease 2019 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 , numerous viral variants have emerged. These variants have shown enhanced transmissibility, virulence, and immune evasion capacity.
Introduction Omicron has 11 mutations at its receptor binding site , which is responsible for most serologic responses. Such mutations preserve the ability of the virus to bind to the host angiotensin-converting enzyme 2 receptor while evading neutralizing antibodies that are present after natural infection or vaccination.
About the study The researchers used their new modeling platform, ScanNet, based on geometric deep learning, to predict B-cell and protein-protein binding sites using either the experimental or computational structure. In addition, ScanNet provides a residue-wise probability score for each epitope called the antigenicity profile.
Related StoriesCompared with the 26% reduction in antigenicity shown by all point mutants, the downward trend shown by Omicron appears to be due to evolutionary pressure, with similarly acting mutations displaying reciprocal reinforcement. While most antibodies target the RBS, which shows extreme variability among VOCs, the other antibodies bind to conserved epitopes. Antibody titers in serum samples from wild-type-immunized mice were comparably high against Alpha and Delta VOCs but less against Beta. The most significant reduction was against Omicron.Omicron-immunized sera contained markedly lower serologic titers against any other VOC but exhibited efficient binding for Omicron RBS.
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