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. 2023 May 17;15(5):1179.
doi: 10.3390/v15051179.

Improved Performance of the QuantiFERON-SARS-CoV-2 Assay with the Extended Set

Lydia Lamara Mahammed  1 , Kahina Bensaid  1 , Sarah Ait-Seddik  2 , Amel Larinouna  2 , Ghania Brahimi  2 , Rosa Belkaid  2 , Ouassila Hamzaoui  3 , Soumia Meriem Rouaki  4 , Cherifa Idder  4 , Ines Allam  1 , Reda Djidjik  1
Affiliations

Improved Performance of the QuantiFERON-SARS-CoV-2 Assay with the Extended Set

Lydia Lamara Mahammed et al. Viruses. .

Abstract

Multiple assays have been developed for the characterization of the functional activation of SARS-CoV-2 specific T-cells. This study was conducted to assess the post-vaccination and post-infection T cell response, as detected by the QuantiFERON-SARS-CoV-2 assay using the combination of three SARS-CoV-2 specific antigens (Ag1, Ag2 and Ag3). An amount of 75 participants with different infection and vaccination backgrounds were recruited for the evaluation of humoral and cellular immune responses. An elevated IFN-γ response in at least one Ag tube was observed in 69.2% of convalescent subjects and 63.9% of vaccinated ones. Interestingly, in a healthy unvaccinated case and three convalescents with negative IgG-RBD, we detected a positive QuantiFERON test after stimulation with Ag3. The majority of the T cell responders reacted simultaneously to the three SARS-CoV-2 specific antigens, and Ag3 demonstrated the highest rate of reactivity. At univariable analysis, the only factor that was associated with an absence of a cellular response was time from blood collection, being less than 30 days (OR:3.5, CI95% [1.15-10.50], p = 0.028). Overall, the inclusion of Ag3 improved the performance of the QuantiFERON-SARS-CoV-2 and showed a particular interest among subjects who fail to achieve a measurable antibody response after infection or vaccination.

Keywords: COVID-19; QuantiFERON-SARS-CoV-2; cellular immunity; vaccine.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study, in the collection, analyses, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Flow chart of patients’ enrollment. RBD: anti-receptor binding domain. Nab: neutralizing antibodies. IGRA: IFN-Gamma Release Assay.
Figure 2
Figure 2
Evaluation of SARS-CoV-2 specific humoral response among convalescent and vaccinated subjects. (a) Anti-receptor binding domain (RBD) IgG (b) neutralizing antibody (Nab) (c) correlation between RBD and Nab. ns: not significant.
Figure 3
Figure 3
T cell response to QuantiFERON SARS-CoV-2. (a) Percentage of IGRA responders. (b) IFN-γ-specific T cell response to SARS-CoV-2 antigens among convalescents. (c) IFN-γ-specific T cell response to SARS-CoV-2 antigens among vaccinated subjects. (d) Correlations between the IFN-γ levels of all pairs of tested antigens. (e) Comparison of the levels of IFN-γ induced by each antigen between convalescent and vaccinated participants. ns: Not significant.
Figure 3
Figure 3
T cell response to QuantiFERON SARS-CoV-2. (a) Percentage of IGRA responders. (b) IFN-γ-specific T cell response to SARS-CoV-2 antigens among convalescents. (c) IFN-γ-specific T cell response to SARS-CoV-2 antigens among vaccinated subjects. (d) Correlations between the IFN-γ levels of all pairs of tested antigens. (e) Comparison of the levels of IFN-γ induced by each antigen between convalescent and vaccinated participants. ns: Not significant.
Figure 4
Figure 4
Follow up of humoral and cellular immune responses to SARS-CoV-2 after vaccination at two time points: one month and three months. (a) Anti-receptor binding domain (RBD) IgG. (b) Neutralizing antibody (Nab) (c) response to Ag1. (d) Response to Ag2. (e) Response to Ag3. nbr: number. ns: not significant.
Figure 4
Figure 4
Follow up of humoral and cellular immune responses to SARS-CoV-2 after vaccination at two time points: one month and three months. (a) Anti-receptor binding domain (RBD) IgG. (b) Neutralizing antibody (Nab) (c) response to Ag1. (d) Response to Ag2. (e) Response to Ag3. nbr: number. ns: not significant.
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