SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals.

Bibliographic Details

Main Authors:	Silva,Laís Teodoro da, Ortega,Marina Mazzilli, Tiyo,Bruna Tiaki, Viana,Isabelle Freire Tabosa, Lima,Tayná Evily de, Tozetto-Mendoza,Tania Regina, Oliveira,Luanda Mara da Silva, Teixeira,Franciane Mouradian Emidio, Lins,Roberto Dias, Almeida,Alexandre de, Mendes-Correa,Maria Cassia, Duarte,Alberto Jose da Silva, Oshiro,Telma Miyuki
Format:	Digital revista
Language:	English
Published:	Faculdade de Medicina / USP 2021
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1807-59322021000100346
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