SARS-CoV-2 spike protein ELISA calculations and summary data

Soon after commencement of the SARS-CoV-2 disease outbreak of 2019 (COVID-19), it became evident that the receptor-binding domain of the viral spike protein is the target of neutralizing antibodies that comprise a critical element of protective immunity to the virus.  This study addresses the relative lack of information regarding actual antibody concentrations and binding affinities in convalescent plasma (CP) samples from COVID-19 patients and extends these analyses to post-vaccination (PV) samples to estimate protective IgG antibody (Ab) levels.  A direct enzyme-linked immunosorbent assay (ELISA) was used to measure IgG anti-spike protein (SP) antibodies (Abs) relative to human chimeric spike S1 Ab standards.  Microplate wells were coated with recombinant SP.  Affinities of Ab binding to SP were determined by previously described methods.  Binding affinities were also determined in an RBD-specific sandwich ELISA.  Two indices of protective immunity were determined as permutations of ..., Convalescent plasma (CP) samples were obtained from the University of Texas Health Science Center at Houston (UTHealth)/Memorial Hermann COVID-19 Convalescent Plasma Program under the direction of Dr. Henry E. Wang.  Convalescent plasma (CP) donors previously tested positive for COVID-19, were symptom-free for >14 days, tested negative for COVID-19 antigen prior to donation, and tested positive for CP antibodies.  Donor plasma was collected by the Gulf Coast Regional Blood Center before August 2020, which created a general stock of CP units that were distributed among therapeutic CP programs in the greater Houston area. Each plasma sample derived from a single donor.
Post-vaccination (PV) plasma samples were obtained from Dr. Luis Ostrosky’s laboratory at the Division of Infectious Diseases, Department of Internal Medicine, McGovern School of Medicine of UTHealth.  Two groups of 21 samples, each collected 15-29 days after administration of the first or second dose of the Pfizer or Mo..., , # SARS-CoV-2 Spike Protein ELISA Calculations and Summary Data

[https://doi.org/10.5061/dryad.n5tb2rc4t](https://doi.org/10.5061/dryad.n5tb2rc4t)

## Description of the data and file structure

Data are protective IgG antibody levels against the SARS-CoV-2 spike protein (S1 + S2), determined by quantitative ELISA relative to a chimeric human standard.  Replicate values are the average of several re-assays of the same samples.  Antibody levels were also measured vs. the spike protein receptor binding domain (RBD).  These were corrected for high background levels in that assay.  SP antibody binding affinities were determined as described in the paper and the preprint.  These values were determined for COVID-19 convalescent plasma samples, samples from fully vaccinated individuals, and samples from partially vaccinated (one of two Moderna or Pfizer vaccinations).

### Files and variables

#### File: UTTP34\_ELISA\_Affinity\_Calc\_2.xlsx

**Description:** Calculated affinity values for sta...