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Commercialized kits to assess T-cell responses against SARS-CoV-2 S peptides
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  • Monica Martinez Gallo,
  • Juliana Esperalba-Esquerra,
  • Ricardo Pujol-Borrell,
  • Victor Sanda,
  • Iria Arrese-Muñoz,
  • Candela Fernandez-Naval,
  • Andres Anton-Pagarolas,
  • Victoria Cardona,
  • Moises Labrador-Horrillo,
  • Tomas Pumarola-Suñe,
  • Manuel Hernandez-Gonzalez
Monica Martinez Gallo
Hospital Universitari Vall d'Hebron
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Juliana Esperalba-Esquerra
Hospital Universitari Vall d'Hebron
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Ricardo Pujol-Borrell
Hospital Universitari Vall d'Hebron
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Victor Sanda
Hospital Universitari Vall d'Hebron
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Iria Arrese-Muñoz
Hospital Universitari Vall d'Hebron
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Candela Fernandez-Naval
VHIR
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Andres Anton-Pagarolas
Hospital Universitari Vall d'Hebron
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Victoria Cardona
Hospital Vall d'Hebron
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Moises Labrador-Horrillo
Hospital Universitari Vall d'Hebron

Corresponding Author:mlabrador@vhebron.net

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Tomas Pumarola-Suñe
Hospital Universitari Vall d'Hebron
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Manuel Hernandez-Gonzalez
Hospital Universitari Vall d'Hebron
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Abstract

Background: There is an urgent need to assess the levels of protection generated by natural infection or SARS-CoV-2 vaccines, especially in individuals professionally exposed. Measuring T-cell responses may complement antibody tests currently in use as correlates of protection. Our aim was to assess the feasibility of a validated assay of T-cell responses applicable to large number of samples. Methods: Twenty health-care-workers (HCW) were included. Antibody test to SARS-CoV-2 N and S-proteins in parallel with a commercially available whole-blood-interferon-gamma-release-assay (IGRA) to S-peptides and two detection methods, CLIA and ELISA were determined. Results: IGRA test detected T-cell responses in naturally exposed and vaccinated HCW already after first vaccination dose. The correlation by the two detection methods was very high (R>0.9) and sensitivity and specificity ranged between 100 and 86% and 100-73% respectively. Even though there was a very high concordance between antibody and the IGRA assay in the ability to detect immune response to SARS-CoV-2, there was a relatively low quantitative correlation. In the small group primed by natural infection, one vaccine dose was sufficient to reach immune response plateau. IGRA was positive in one, with Ig(S) antibody negative vaccinated immunosuppressed HCW illustrating another advantage of the IGRA-test. Conclusion: Whole-blood-IGRA-tests amenable to automation and constitutes a promising additional tool for measuring the state of the immune response to SARS-CoV-2; they are applicable to large number of samples and may become a valuable correlate of protection to COVID-19, particularly for