Sequenced from human survivors of COVID19 (SARSCoV2)

This recombinant HRPconjugated antibody is formulated in 0.01 M phosphate buffered saline (150 mM NaCl) PBS pH 7.2 7.4, 1% BSA. (Warning: Use of sodium azide as a preservative will inhibit the enzyme activity of horseradish peroxidase)

This horseradish peroxidase conjugated monoclonal antibody is stable when stored at 28°C. Do not freeze.

Overnight on Blue Ice.

AntiSARSCoV2 Spike RBDHRP, clone 2165, specifically targets an epitope on the SARSCoV2 spike protein receptorbinding domain (RBD).

Severe acute respiratory syndrome coronavirus 2 (SARSCoV2), the causative agent of coronavirus disease 2019 (COVID19), is an enveloped, singlestranded, positivesense RNA virus that belongs to the Coronaviridae family ¹. The SARSCoV2 genome, which shares 79.6% identity with SARSCoV, encodes four essential structural proteins: the spike (S), envelope (E), membrane (M), and nucleocapsid protein (N) ². The S protein is a transmembrane, homotrimeric, class I fusion glycoprotein that mediates viral attachment, fusion, and entry into host cells ³. Each ~180 kDa monomer contains two functional subunits, S1 (~700 a.a) and S2 (~600 a.a), that mediate viral attachment and membrane fusion, respectively. S1 contains two major domains, the Nterminal (NTD) and Cterminal domains (CTD). The CTD contains the receptorbinding domain (RBD), which binds to the angiotensinconverting enzyme 2 (ACE2) receptor on host cells ³⁵. Although both SARSCoV and SARSCoV2 bind the ACE2 receptor, the RBDs only share ~73% amino acid identity, and the SARSCoV2 RBD binds with a higher affinity compared to SARSCoV ^{3, 6}. The RBD is dynamic and undergoes hingelike conformational changes, referred to as the “down” or “up” conformations, which hide or expose the receptorbinding motifs, respectively ⁷. Following receptor binding, S1 destabilizes, and TMPRSS2 cleaves S2, which undergoes a pre to postfusion conformation transition, allowing for membrane fusion ^{8, 9}.

Polyclonal RBDspecific antibodies can block ACE2 binding ^{10, 11}, and antiRBD neutralizing antibodies are present in the sera of convalescent COVID19 patients ¹², identifying the RBD as an attractive candidate for vaccines and therapeutics. In addition, the RBD is poorly conserved, making it a promising antigen for diagnostic tests ^{13 14}. Serologic tests for the RBD are highly sensitive and specific for detecting SARSCoV2 antibodies in COVID19 patients ^{13 15}. Furthermore, the levels of antiRBD antibodies correlated with SARSCoV2 neutralizing antibodies, suggesting the RBD could be used to predict an individual's risk of disease ¹³.

The spike RBD is expressed on the surface of SARSCoV2.

1. Zhou, P., Yang, X., Wang, X. et al. Nature 579, 270–273. 2020.
2. Wu, F., Zhao, S., Yu, B. et al. Nature 579, 265–269. 2020.
3. Wrapp D, Wang N, Corbett KS, et al. bioRxiv. 2020.02.11.944462. 2020.
4. Walls AC, Park YJ, Tortorici MA, Wall A, McGuire AT, Veesler D. Cell. 181(2):281292.e6. 2020.
5. Li W, Zhang C, Sui J, et al. EMBO J. 24(8):16341643. 2005.
6. Shang, J., Ye, G., Shi, K. et al. Nature 581, 221–224. 2020.
7. Gui M, Song W, Zhou H, et al. Cell Res. 27(1):119129. 2017.
8. Walls AC, Tortorici MA, Snijder J, et al. Proc Natl Acad Sci U S A. 114(42):1115711162. 2017.
9. Hoffmann M, KleineWeber H, Schroeder S, et al. Cell. 181(2):271280.e8. 2020.
10. Huo J, Zhao Y, Ren J, et al. Cell Host Microbe. S19313128(20)303516. 2020.
11. Tai, W., He, L., Zhang, X. et al. Cell Mol Immunol 17, 613–620. 2020.
12. Cao Y, Su B, Guo X, et al. Cell. 182(1):7384.e16. 2020.
13. Premkumar L, SegoviaChumbez B, Jadi R, et al. medRxiv; 2020.
14. Quinlan BD, Mou H, Zhang L, et al. bioRxiv; 2020.
15. Olba NM, Muller MA, Li W, et al. medRxiv; 2020.