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. 2023 Feb 26;13(5):889.
doi: 10.3390/diagnostics13050889.

Neutralizing Antibodies against SARS-CoV-2 Beta and Omicron Variants Inhibition Comparison after BNT162b2 mRNA Booster Doses with a New PETIA sVNT Assay

Marta Fogolari  1   2 , Bruno Daniele Leoni  3 , Marina De Cesaris  1 , Rita Italiano  3 , Flavio Davini  1   2 , Ginevra Azzurra Miccoli  4 , Daniele Donati  4 , Luigi Clerico  5 , Andrea Stanziale  5 , Giovanni Savini  6 , Nicola Petrosillo  4 , Massimo Ciccozzi  7 , Lorenzo Sommella  8 , Elisabetta Riva  1   9 , Paolo Fazii  5 , Silvia Angeletti  1   2
Affiliations

Neutralizing Antibodies against SARS-CoV-2 Beta and Omicron Variants Inhibition Comparison after BNT162b2 mRNA Booster Doses with a New PETIA sVNT Assay

Marta Fogolari et al. Diagnostics (Basel). .

Abstract

Background: Monitoring antibody response following SARS-CoV-2 vaccination is strategic, and neutralizing antibodies represent the gold standard. The neutralizing response to Beta and Omicron VOCs was evaluated versus the gold standard by a new commercial automated assay.

Methods: Serum samples from 100 healthcare workers from the Fondazione Policlinico Universitario Campus Biomedico and the Pescara Hospital were collected. IgG levels were determined by chemiluminescent immunoassay (Abbott Laboratories, Wiesbaden, Germany) and serum neutralization assay as the gold standard. Moreover, a new commercial immunoassay, the PETIA test Nab (SGM, Rome, Italy), was used for neutralization evaluation. Statistical analysis was performed with R software, version 3.6.0.

Results: Anti-SARS-CoV-2 IgG titers decayed during the first ninety days after the vaccine second dose. The following booster dose significantly (p < 0.001) increased IgG levels. A correlation between IgG expression and neutralizing activity modulation was found with a significant increase after the second and the third booster dose (p < 0.05. Compared to the Beta variant of the virus, the Omicron VOC was associated with a significantly larger quantity of IgG antibodies needed to achieve the same degree of neutralization. The best Nab test cutoff for high neutralization titer (≥1:80) was set for both Beta and Omicron variants.

Conclusion: This study correlates vaccine-induced IgG expression and neutralizing activity using a new PETIA assay, suggesting its usefulness for SARS-CoV2 infection management.

Keywords: PETIA assay; SARS-CoV-2; VOCs; neutralization assay; serum antibodies; vaccine.

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Conflict of interest statement

B.D.L. and R.I. are currently employed by Abbott. The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Anti-SARS-CoV-2- IgG and Neutralizing antibodies (Nab) correlation. Anti-RBD IgG levels are plotted against neutralizing-antibody-mediated percentage inhibition. The trend line equation is depicted in the picture: Nab% inhibition = 15,493 ln(x) − 30.71. Spearman Rho correlation was 0.96 (p < 0.001). Blue circles correspond to single value determination.
Figure 2
Figure 2
Box-and-whiskers plot of anti-SARS-CoV-2 IgG receptor-binding domain (RBD) levels at different neutralization. Dilution titers before and after Comirnaty vaccine third dose administration. Box plots indicate the median and interquartile range (IQR); the whiskers represent 1.5 times the IQR. Significant p-values are indicated over the brackets. Colors are related to the analyzed VOC as depicted in the picture legend (Panel (A)). Titer distribution comparison of Beta and Omicron VOCs after the third dose. Color intensity shading from light yellow to green reflects the number of subjects associated with the different variant dilution titers (panel (B)).
See this image and copyright information in PMC

Comment in

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