Abstract
The immune response promoted by SARS-CoV-2 vaccination is relevant to develop novel vaccines and optimized prevention strategies. We analyzed the adaptive immunity in healthy donors (HD) and convalescent individuals (CD), before and after administering BNT162b2 vaccine. Our results revealed specific changes in CD4+ T cell reactivity profile in vaccinated HD and CD, with an increase in S1 and S2 positive individuals, proportionally higher for S2. On the contrary, NCAP reactivity observed in HD and CD patients was no longer detectable after vaccination. Despite the substantial antibody response in CD, MPro-derived peptides did not elicit CD4+ lymphocyte activation in our assay in either condition. HD presented an increment in anti-S and anti-RBD IgG after first dose vaccination, which increased after the second vaccination. Conversely, anti-S and anti-RBD IgG and IgA titers increased in already positive CD after first dose administration, remaining stable after second dose inoculation. Interestingly, we found a strong significant correlation between S1-induced CD4+ response and anti-S IgA pre-vaccination, which was lost after vaccine administration.
Highlights
The development of humoral and cellular immunity against SARS-CoV-2, the causative agent of new coronavirus disease (COVID-19) [1], has been the subject of numerous studies, given its importance in the pathogenesis of the disease and its usefulness from a diagnostic and epidemiological perspective [2, 3]
We evaluated T cell response after stimulation with peptide pools from SARS-CoV-2 proteins (S1, S2, RBD domain, VME1, NCAP and Mpro) in 10 healthy donors (HD) and 11 convalescent individuals (CD)
T cell activity was determined by an activation induced marker (AIM) assay, based on detecting surface expression of CD25 and CD69 in CD4+ lymphocytes by flow cytometry (Supplementary Figure 1)
Summary
The development of humoral and cellular immunity against SARS-CoV-2, the causative agent of new coronavirus disease (COVID-19) [1], has been the subject of numerous studies, given its importance in the pathogenesis of the disease and its usefulness from a diagnostic and epidemiological perspective [2, 3]. Numerous studies show the presence of T lymphocytes reactive against SARS-CoV-2 epitopes in a variable percentage of healthy individuals [3, 4, 10,11,12,13]. In most cases, these epitopes have a high degree of homology with sequences present in common cold coronaviruses. These epitopes have a high degree of homology with sequences present in common cold coronaviruses These lymphocytes could be responsible for heterologous immunity, conferring resistance to infection by SARS-CoV-2 or leading to milder COVID-19 symptoms, but no studies confirm this hypothesis
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