Abstract
Objective: We investigated blood samples from fully SARS-CoV2-vaccinated subjects and from previously positive tested patients up to one year after infection with SARS-CoV2, and compared short- and long-term T cell and antibody responses, with a special focus on the recently emerged delta variant (B.1.617.2).
Methods and results: In 23 vaccinated subjects, we documented high anti-SARS-CoV2 spike protein receptor binding domain (RBD) antibody titers. Average virus neutralization by antibodies, assessed as inhibition of ACE2 binding to RBD, was 2.2-fold reduced for delta mutant vs. wild type (wt) RBD. The mean specific antibody titers were lower one year after natural infection than after vaccination; ACE2 binding to delta mutant vs. wt RBD was 1.65-fold reduced. In an additional group, omicron RBD binding was reduced compared to delta. Specific CD4+ T cell responses were measured after stimulation with peptides pools from wt, alpha, beta, gamma, or delta variant SARS-CoV2 spike proteins by flow cytometric intracellular cytokine staining. There was no significant difference in cytokine production of IFN-γ, TNF-α, or IL-2 between vaccinated subjects. T cell responses to wt or mutant SARS-CoV2 spike were significantly weaker after natural occurring infections compared to those in vaccinated individuals.
Conclusion: Antibody neutralisation of the delta mutant was reduced compared to wt, as assessed in a novel inhibition assay with a finger prick blood drop. Strong CD4 T cell responses were present against wt and mutant SARS-CoV2 variants, including the delta (B.1.617.2) strain, in fully vaccinated individuals, whereas they were partly weaker 1 year after natural infection. Hence, immune responses after vaccination are stronger compared to those after naturally occurring infection, pointing out the need of the vaccine to overcome the pandemic.
【초록키워드】 antibodies, SARS-CoV2, immune response, vaccination, pandemic, antibody, variant, Infection, B.1.617.2, peptide, delta variant, CD4, variants, Spike protein, Receptor binding domain, T cell, RBD, immune responses, response, T cell responses, Patient, Antibody titer, Virus neutralization, peptides, Alpha, mutant, natural infection, wild type, T cell response, neutralisation, cytokine production, CD4+ T cell, Blood, Antibody titers, IFN-γ, TNF-α, IL-2, Stimulation, ACE2 binding, strain, Finger prick, significant difference, no significant difference, Blood samples, subject, blood sample, RBD binding, vaccinated individuals, positive, Specific, responses, intracellular cytokine staining, flow cytometric, flow cytometric intracellular cytokine staining, tested, significantly, investigated, reduced, subjects, overcome, the vaccine, were measured, was reduced, Strong, 【제목키워드】 SARS-CoV2, vaccination, Immunity, mutant, humoral,