COVID-19 survival associates with the immunoglobulin response to the SARS-CoV-2 spike receptor binding domain

Abstract

BACKGROUND. Serological assays are of critical importance to investigate correlates of response and protection in coronavirus disease 2019 (COVID-19), to define previous exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in populations, and to verify the development of an adaptive immune response in infected individuals. METHODS. We studied 509 patients confirmed to have COVID-19 from the San Raffaele Hospital of Milan and 480 samples of prepandemic organ donor sera collected in 2010-2012. Using fluid-phase luciferase immune precipitation (LIPS) assays, we characterized IgG, IgM, and IgA antibodies to the spike receptor binding domain (RBD), S1+S2, nucleocapsid, and ORF6 to ORF10 of SARS-CoV-2, to the HCoV-OC43 and HCoV-HKU1 betacoronaviruses spike S2, and the H1N1Ca2009 flu virus hemagglutinin. Sequential samples at 1 and 3 months after hospital discharge were also tested for SARS-CoV-2 RBD antibodies in 95 patients. RESULTS. Antibodies developed rapidly against multiple SARS-CoV-2 antigens in 95% of patients by 4 weeks after symptom onset and IgG to the RBD increased until the third month of follow-up. We observed a major synchronous expansion of antibodies to the HCoV-OC43 and HCoV-HKU1 spike S2. A likely coinfection with influenza was neither linked to a more severe presentation of the disease nor to a worse outcome. Of the measured antibody responses, positivity for IgG against the SARS-CoV-2 spike RBD was predictive of survival. CONCLUSION. The measurement of antibodies to selected epitopes of SARS-CoV-2 antigens can offer a more accurate assessment of the humoral response in patients and its impact on survival. The presence of partially cross-reactive antibodies with other betacoronaviruses is likely to impact on serological assay specificity and interpretation.

Antibody response to multiple antigens of SARS-CoV-2 in patients with diabetes: an observational cohort study

“…For this study, we used a LIPS liquid phase immunoassay developed on the basis of our prior expertise. The description of the assay performance and potential caveats [27,28] falls outside the scope of this study and is being published elsewhere [25]. Taken together, our data support the evidence of an efficient humoral response in patients with diabetes, as the prevalence of positivity for the different classes of antibodies to multiple SARS-CoV-2 antigens was superimposable, as for timing and antibody titres, to that of non-diabetic patients and was not influenced by glucose levels.…”

“…Anti-SARS-CoV-2 antibody determination To investigate the presence of anti-SARS-CoV-2 antibodies in patients with COVID-19 pneumonia, we developed a novel assay based on the luciferase immunoprecipitation system (LIPS) format [25]. LIPS is a derivative of the radio-binding assay in which serum antibodies are used to immunoprecipitate radiolabelled antigens in the liquid phase.…”

“…In LIPS, the use of radiolabelled tracers is superseded in favour of chimeric recombinant antigens tagged with a luciferase reporter. The antigens used in this study were constructed in our lab [25]: sNLuc-SARS-CoV-2 beta coronavirus S1 receptor-binding domain (RBD) aa 319-541; sNLuc-SARS-CoV-2 beta coronavirus S1+S2 spike protein; and NLuc-SARS-CoV-2 beta coronavirus nucleocapsid protein (NP). For the LIPS assay, the antigen of interest was diluted in 20 mmol/l Tris buffer, 150 mmol/l NaCl, 0.5% Tween-20, pH 7.4 (TBST) buffer and adjusted to achieve a luciferase activity corresponding to a final concentration of 4 × 106 light units (LU)/25 μl.…”

Pre-Existing Cytokine and NLRP3 Inflammasome Activation and Increased Vascular Permeability in Diabetes: A Possible Fatal Link With Worst COVID-19 Infection Outcomes?

“…In addition, this state of low-grade inflammation in COVID-19 diabetic patients may lead to an increase of the percentage of proinflammatory memory B cells and a decrease of antiinflammatory B-cells, resulting in an early maturation of the antibody response. In that way, Secchi M et al have indicated that SARS-CoV-2 antigens, such as the SARS-CoV-2 spike Receptor Binding Domain, lead to a rapid development of humoral response and superimposable antibody response compared to non-diabetic patients independently of glucose levels (28,36).…”

Mild SARS-CoV-2 Infection After Gene Therapy in a Child With Wiskott-Aldrich Syndrome: A Case Report

“…Specific antibodies to different SARS-CoV2 antigens were tested by a luciferase immunoprecipitation system (LIPS) assay developed in house (13). Serum IgG to Nucleocapsid protein (NP), Receptor binding domain (RBD) and Spike proteins (S1S2) were positive by day 6 after first positive swab and at day 61 ( Figure 2B), reaching levels comparable to those of children who experienced SARS-CoV2 infection (n=3) and higher than the mother ( Figure 2C).…”