Development of an in-house quantitative ELISA for the evaluation of different Covid-19 vaccines in humans

Gdoura, Mariem; Ghaloum, Fatma Ben; Hamida, Meriem Ben; Chamsa, Wafa; Triki, Henda; Bahloul, Chokri

doi:10.1038/s41598-022-15378-1

Cited by 10 publications

(8 citation statements)

References 27 publications

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“…Using a threshold of Anti-Spike-1-RBD antibody ≥ 100 U/mL as a correlate of COVID-19 protection [ 6 ], it is remarkable that 84.6% of subjects met 6-month threshold criterion. Of note, there is limited data regarding the clinical applicability of using this Elecsys Anti-SARS-CoV-2 S RBD assay and the implications of its semi-quantitative antibody levels as it relates to the degree of immunity or protection against COVID-19 in vaccinated individuals [ 8 ]. Our cohort had significant variability and rather broad range of Anti-Spike-1-RBD levels, which may reflect participant characteristics, co-morbidities influencing vaccine responses.…”

Section: Discussionmentioning

confidence: 99%

“…Notwithstanding, the absence of standardized antibody assays remains challenging for direct study result comparison. Thus, a more standardized method of assessing SARS-CoV-2 humoral immunity and correlates of immune protection is needed; ongoing research is being conducted to establish international standards to interpret humoral immunity results using different testing platforms and units of measurement [ 8 ]. We excluded participants with prior or breakthrough COVID-19, so as not to bias immunologic assessments, which may inadvertently select for more optimal vaccine responses.…”

Section: Discussionmentioning

confidence: 99%

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Long-term quantitative assessment of anti-SARS-CoV-2 spike protein immunogenicity (QUASI) after COVID-19 vaccination in older people living with HIV (PWH)

et al. 2022

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Background The durability of immune responses to COVID-19 vaccines among older people living with HIV (PWH) is clinically important. Methods We aimed to assess vaccine-induced humoral immunity and durability in older PWH (≥ 55 years, n = 26) over 6 months (post-initial BNT162b2 series). A secondary and exploratory objective was to assess T-cell response and BNT162b2 booster reactogenicity, respectively. Our Visit 1 (3 weeks post-initial BNT162b2 dose) SARS-CoV-2 humoral immunity results are previously reported; these subjects were recruited for Visit 2 [2 weeks (+ 1 week window) post-second vaccination] and Visit 3 [6 months (± 2 week window) post-initial vaccination] in a single-center longitudinal observational study. Twelve participants had paired Visit 2/3 SARS-CoV-2 Anti-Spike IgG data. At Visit 3, SARS-CoV-2 Anti-Spike IgG testing occurred, and 5 subjects underwent T-cell immune response evaluation. Thereafter, subjects were offered BNT162b2 booster (concurrent day outside our study) per US FDA/CDC guidance; reactogenicity was assessed. The primary study outcome was presence of detectable Visit 3 SARS-CoV-2 Anti-Spike-1-RBD IgG levels. Secondary and exploratory outcomes were T-cell immune response and BNT162b2 booster reactogenicity, respectively. Wilcoxon signed-rank tests analyzed median SARS-CoV-2 Anti-Spike IgG 6-month trends. Results At Visit 3, 26 subjects underwent primary analysis with demographics noted: Median age 61 years; male n = 16 (62%), female n = 10 (38%); Black n = 13 (50%), White n = 13 (50%). Most subjects (n = 20, 77%) had suppressed HIV viremia on antiretroviral therapy, majority (n = 24, 92%) with CD4 > 200 cells/µL. At Visit 3, 26/26 (100%) had detectable Anti-Spike-1-RBD (≥ 0.8 U/mL). Among 12 subjects presenting to Visit 2/3, median SARS-CoV-2 Anti-Spike 1-RBD was 2087 U/mL at Visit 2, falling to 581.5 U/mL at Visit 3 (p = 0.0923), with a median 3.305-fold decrease over 6 months. Among subjects (n = 5) with 6-month T-cell responses measured, all had detectable cytokine-secreting anti-spike CD4 responses; 3 had detectable CD4 + Activation induced marker (AIM) + cells. Two had detectable cytokine-secreting CD8 responses, but all had positive CD8 + AIM + cells. Conclusions Among older PWH, SARS-CoV-2 Anti-Spike IgG and virus-specific T-cell responses are present 6 months post-primary BNT162b2 vaccination, and although waning, suggest retention of some degree of long-term protective immunity.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Long-term quantitative assessment of anti-SARS-CoV-2 spike protein immunogenicity (QUASI) after COVID-19 vaccination in older people living with HIV (PWH)

et al. 2022

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“…After screening 38 studies (Figure 1) and excluding 16 (Supplementary references), 22 studies were eligible (18 retrieved from the main search and another 4 retrieved from cited/citation searches). [3][4][5][6][7][8][9][10][11][12][13][14][22][23][24][25][26][27][28][29][30][31] 19 studies were published in peer-reviewed journals and 3 were preprints. Other studies screened in-depth and excluded are shown in Supplementary References along with the reason for exclusion.…”

Section: Eligible Studiesmentioning

confidence: 99%

Pre-pandemic cross-reactive humoral immunity to SARS-CoV-2 in Africa: systematic review and meta-analysis

Ioannidis

Contopoulos‐Ioannidis

2022

Preprint

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Background: Low numbers of recorded COVID-19 deaths in Africa may be due to undercounting and/or protection due to demographic and/or other factors, including pre-existing immunity. Several studies have assessed pre-pandemic samples for anti-SARS-CoV-2 antibodies with heterogeneous results. Methods: We performed a systematic review and meta-analysis of studies evaluating pre-pandemic African samples for anti-SARS-CoV-2 antibody activity using pre-set assay-specific thresholds for seropositivity. Data where assay thresholds were calibrated on African populations were excluded. Searches used PubMed (September 13, 2022), reference lists of retrieved papers and citing articles (Google Scholar). Data were extracted independently by two authors on study and assay characteristics, and number of positive and tested samples. Datasets were classified according to malaria, dengue, and HIV burden. Proportions of seropositivity were combined with random effects meta-analysis. Results: 22 articles with 117 datasets were eligible, including 2,971 positives among 21,988 measurements (13.5%) with large between-dataset heterogeneity. Positivity was higher for anti-S1 (25%) and lower for anti-RBD antibodies (8%). Positivity was non-significantly higher for IgM than for IgG antibodies. Positivity was seen prominently in countries where malaria transmission occurs throughout and in datasets enriched in malaria cases (17%, 95% CI, 15-19%) versus 1%, 95% CI 0-2% in other datasets). There were modest differences according to dengue burden (15% versus 11%). Substantial SARS-CoV-2 reactivity was seen in high malaria burden with or without high dengue burden (seropositivity 19% and 12%, respectively), and not without high malaria burden (seropositivity 2% and 0% with and without high dengue burden, respectively). There were modestly lower proportions of positivity in datasets with >10% of HIV-infected participants (8% versus 15% in others), but no association according to HIV serostatus in individual samples (summary odds ratio 0.97, 95% CI, 0.55-1.70). Interpretation: Pre-pandemic samples from Africa show high levels of anti-SARS-CoV-2 seropositivity that tracks especially with malaria.

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“…The spike (S) and nucleoprotein (N) proteins were of particular emphasis, being the most immunogenic of the SARS-CoV-2 structural proteins ( 16 , 17 ). Since COVID-19 vaccines contain and elicit antibody responses to the spike protein, antibody responses against the spike protein are often used to evaluate vaccine immunogenicity ( 17 , 18 ). In addition, antibodies targeting the nucleoprotein imply infection and re-infection ( 19 ) in the absence of RT-PCR, as is often the case in low-resource settings in Sub-Saharan Africa, where there is inadequate coverage of molecular diagnostics ( 20 ).…”

Section: Introductionmentioning

confidence: 99%

Optimisation and Validation of a conventional ELISA and cut-offs for detecting and quantifying anti-SARS-CoV-2 Spike, RBD, and Nucleoprotein IgG, IgM, and IgA antibodies in Uganda

Oluka¹,

Namubiru²,

Kato³

et al. 2023

Front. Immunol.

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There is an urgent need for better immunoassays to measure antibody responses as part of immune-surveillance activities and to profile immunological responses to emerging SARS-CoV-2 variants. We optimised and validated an in-house conventional ELISA to identify and quantify SARS-CoV-2 spike- (S-), receptor binding domain- (RBD-), and nucleoprotein- (N-) directed IgG, IgM, and IgA binding antibodies in the Ugandan population and similar settings. Pre- and post-pandemic specimens were used to compare the utility of mean ± 2SD, mean ± 3SD, 4-fold above blanks, bootstrapping, and receiver operating characteristic (ROC) analyses in determining optimal cut-off optical densities at 450 nm (OD) for discriminating between antibody positives and negatives. “Limits of detection” (LOD) and “limits of quantitation” (LOQ) were validated alongside the assay’s uniformity, accuracy, inter-assay and inter-operator precision, and parallelism. With spike-directed sensitivity and specificity of 95.33 and 94.15%, respectively, and nucleoprotein sensitivity and specificity of 82.69 and 79.71%, ROC was chosen as the best method for determining cutoffs. Accuracy measurements were within the expected CV range of 25%. Serum and plasma OD values were highly correlated (r = 0.93, p=0.0001). ROC-derived cut-offs for S-, RBD-, and N-directed IgG, IgM, and IgA were 0.432, 0.356, 0.201 (S), 0.214, 0.350, 0.303 (RBD), and 0.395, 0.229, 0.188 (N). The sensitivity and specificity of the S-IgG cut-off were equivalent to the WHO 20/B770-02 S-IgG reference standard at 100% level. Spike negative IgG, IgM, and IgA ODs corresponded to median antibody concentrations of 1.49, 3.16, and 0 BAU/mL, respectively, consistent with WHO low titre estimates. Anti-spike IgG, IgM, and IgA cut-offs were equivalent to 18.94, 20.06, and 55.08 BAU/mL. For the first time, we provide validated parameters and cut-off criteria for the in-house detection of subclinical SARS-CoV-2 infection and vaccine-elicited binding antibodies in the context of Sub-Saharan Africa and populations with comparable risk factors.

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Development of an in-house quantitative ELISA for the evaluation of different Covid-19 vaccines in humans

Cited by 10 publications

References 27 publications

Long-term quantitative assessment of anti-SARS-CoV-2 spike protein immunogenicity (QUASI) after COVID-19 vaccination in older people living with HIV (PWH)

Long-term quantitative assessment of anti-SARS-CoV-2 spike protein immunogenicity (QUASI) after COVID-19 vaccination in older people living with HIV (PWH)

Pre-pandemic cross-reactive humoral immunity to SARS-CoV-2 in Africa: systematic review and meta-analysis

Optimisation and Validation of a conventional ELISA and cut-offs for detecting and quantifying anti-SARS-CoV-2 Spike, RBD, and Nucleoprotein IgG, IgM, and IgA antibodies in Uganda

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