Detection of Neutralizing Antibodies against Omicron Subvariants BA.1, BA.2 and BA.4/5

New SARS-CoV-2 Omicron subvariants are rapidly spreading worldwide due to their enhanced immune evasion properties. Detection of anti-spike neutralizing antibodies (NAbs) can be used as a measurable indicator of protective immunity to these subvariants. NAbs inhibit binding of the SARS-CoV-2 spike protein receptor-binding domain (RBD) to the host cell ACE2 receptor. Studies indicate the crucial roles of NAbs for patient survival and viral control (1). A better understanding of the strength and duration of immune protection is important for epidemiological studies, public health measures, and future vaccination campaigns (2,3).

NAb levels are generally measured using live virus-based inhibition assays. However, these require several days to perform and become cumbersome when processing a large number of samples. High-throughput immunoassays are able to report the presence of anti-RBD or anti-spike antibodies and establish a correlation with neutralizing activity (4).

GeneTex has streamlined the immunoassay-based neutralizing antibody detection process by creating the SARS-CoV-2 Neutralizing Antibody ELISA Kit (Omicron BA.1 / BA.2 / BA.4 / BA.5) (GTX537233) (see schematic below). The kit employs a competitive ELISA strategy with plate-immobilized recombinant ACE2 protein bound by soluble recombinant His-tagged trimeric spike ECD proteins from wildtype SARS-CoV-2, Omicron BA.1, Omicron BA.2, or Omicron BA.4/5. Test and control samples are first applied to the wells to allow binding of any NAb in the sample to the subsequently added spike proteins. Both neutralizing (positive control; NAb) and non-neutralizing (negative control; Non-NAb) antibodies for semi-quantification of the neutralization capability of each test sample are included. Assay readout is generated by an HRP-conjugated anti-His tag antibody that binds to the bound spike protein with TMB signal development. The kit is compatible with the Dynex DS2® automatic ELISA system and is thus ideal for high-throughput analysis.

GeneTex offers an extensive catalog of well-validated antibodies and recombinant proteins, in addition to the kit described here, for SARS-CoV-2 Omicron research. Please see the featured products below and visit our website at www.genetex.com for more information.

Featured Product

SARS-CoV-2 Neutralizing Antibody ELISA Kit (Omicron BA.1 / BA.2 / BA.4 / BA.5) (GTX537233)

The NAb positive control antibodies are a mixture of SARS-CoV-2 (COVID-19) Spike RBD antibody [HL1003] (GTX635792) (104-13333 pM) (left) and SARS-CoV-2 (COVID-19) Spike RBD Omicron antibody [HL1867] (GTX637592) (104-13333 pM) (right) that together inhibit binding of the WT and three Omicron subvariant (BA.1, BA.2, and BA.4/5) spike proteins included in the kit.

References:

1. Nat Commun. 2021 May 11;12(1):2670. doi: 10.1038/s41467-021-22958-8.
2. LoS Med. 2022 May 17;19(5):e1003991. doi: 10.1371/journal.pmed.1003991.
3. Nat Med. 2022 Mar;28(3):496-503. doi: 10.1038/s41591-022-01715-4.
4. J Med Virol. 2022 Jan;94(1):388-392. doi: 10.1002/jmv.27287.