SARS-CoV-2 specific T-cell immunity in COVID-19 convalescent patients and unexposed controls measured by ex vivo ELISpot assay. (July 2021)

• Record Type: Journal Article
• Authors: Cassaniti, Irene; Percivalle, Elena; Bergami, Federica; Piralla, Antonio; Comolli, Giuditta; Bruno, Raffaele; Vecchia, Marco; Sambo, Margherita; Colaneri, Marta; Zuccaro, Valentina; Benazzo, Marco; Robotti, Carlo; Calastri, Anna; Maiorano, Eugenia; Ferrari, Alessandro; Cambiè, Giuseppe; Baldanti, Fausto
• Is Part Of: Clinical microbiology and infection. Volume 27:Number 7(2021)
• Page Start: 1029
• Page End: 1034
• Publication Date: 2021-07
• Subjects: ELISpot -- Humoral response -- Neutralizing antibodies -- SARS-CoV-2 -- T-cell response; Medical microbiology -- Periodicals; Diagnostic microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.01
• DOI: 10.1016/j.cmi.2021.03.010
• Languages: English
• ISSNs: 1198-743X

Abstract

Abstract: Objectives: SARS-CoV-2 T-cell response characterization represents a crucial issue for defining the role of immune protection against COVID-19. The aim of the study was to assess the SARS-CoV-2 T-cell response in a cohort of COVID-19 convalescent patients and in a group of unexposed subjects. Methods: SARS-CoV-2 T-cell response was quantified from peripheral blood mononuclear cells (PBMCs) of 87 COVID-19 convalescent subjects (range 7–239 days after symptom onset) and 33 unexposed donors by ex vivo ELISpot assay. Follow-up of SARS-CoV-2 T-cell response was performed in ten subjects up to 12 months after symptom onset. The role of SARS-CoV-2 specific CD4 and CD8 T cells was characterized in a group of COVID-19 convalescent subjects. Moreover, neutralizing antibodies were determined in serum samples. Results: In 14/33 (42.4%) unexposed donors and 85/87 (97.7%) COVID-19 convalescent subjects a positive result for at least one SARS-CoV-2 antigen was observed. A positive response was observed up to 12 months after COVID-19 infection (median 246 days after symptom onset; range 118–362 days). Of note, SARS-CoV-2 T-cell response seems to be mainly mediated by CD4 T cells. A weak positive correlation was observed between Spike-specific T-cell response and neutralizing antibody titre (p 0.0028; r 2 = 0.2891) and positive SARS-CoV-2 T-cell response was observed in 8/9 (88.9%) COVID-19 convalescent subjects with undetectable SARS-CoV-2 neutralizing antibodies. Discussion: Cross-reactive SARS-CoV-2 T-cell response in uninfected patients may be due to previous infections with other common coronaviruses. Our data suggest that long-term SARS-CoV-2 T-cell response might accompany a waning humoral response.