Titers of antibodies against ancestral SARS-CoV-2 correlate with levels of neutralizing antibodies to multiple variants

Abstract

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 serum samples. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Determinants of humoral and cellular immune responses to three doses of mRNA SARS-CoV-2 vaccines in older adults: a longitudinal cohort study

“…Serum IgG anti-receptor binding domain of the SARS-CoV-2 spike protein was measured in BAU/mL, as described by Tran and colleagues. 19 Thawed cryopreserved peripheral blood mononuclear cells were stimulated for 24 h at 37°C in complete medium (RPMI 1640 Medium, 10% fetal bovine serum, 1 mM sodium pyruvate, 1% MEM non-essential amino acids, 12 μg/mL gensumycin (all ThermoFisher Scientific, Waltham, MA, USA), and 50 nM 1-thioglycerol (Sigma-Aldrich, Merck, Darmstadt, Germany) with SARS-CoV-2 spike peptides (Wuhan-Hu-1 strain, and alpha [B.1.1.7], delta, and omicron VOCs), spike and nucleocapsid pools of seasonal human coronaviruses (HCoV-OC43, HCoV-NL63, and HCoV-HKU-1), and cytomegalovirus pp65 peptides ( appendix p 13 ). Brefeldin A (BD Golgi Plug, BD Biosciences, San Jose, CA, USA) was added after 2 h. Activated CD4 T cells were identified by CD40L and TNF-α coexpression and CD8 T cells by IFN-γ or TNF-α expression ( appendix p 4 ).…”

Seroprevalence of SARS-CoV-2 and humoral immune responses to mRNA vaccines among people who use drugs - In the light of tailored mitigating strategies

“…Detection of antibodies to virus proteins: Antibodies to proteins from SARS-CoV-2, the seasonal coronaviruses OC43, HKU1, NL63 and 229E, and Epstein Barr Virus (EBV) were measured as previously described (21,22). Brie y, polymer beads with uorescent bar codes were coupled to neutravidin and then to biotinylated virus proteins (Spike-FL), RBD and nucleocapsid, S1 domains of spike proteins from OC43, HKU1, NL63 and 229E, and the nuclear protein from EBV (EBNA1).…”

“…Beads were pelleted by centrifugation and labelled successively with digoxigenin-conjugated recombinant human ACE2 and anti-Digoxin (Jackson Immunoresearch) conjugated in-house to PE. The beads were analysed by ow cytometry as described above (21).…”

STAR SIGN study: Evaluation of COVID‐19 vaccine efficacy against the SARS‐CoV‐2 variants BQ.1.1 and XBB.1.5 in patients with inflammatory bowel disease

“…46 In contrast to previous studies, iant. 54,55 In our study population, we found a strong pairwise correlation between anti-spike IgG concentrations and surrogate virus neutralisation against all tested SARS-CoV-2 subvariants at both timepoints. Spearman's rho was greater at visit 2 compared to visit 1 for all subvariants and greater for wild-type than for each omicron sublineage, respectively.…”