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Front Immunol ; 13: 863039, 2022.
Article in English | MEDLINE | ID: covidwho-1775685


Evaluating long-term protection against SARS-CoV-2 variants of concern in convalescing individuals is of high clinical relevance. In this prospective study of a cohort of 46 SARS-CoV-2 patients infected with the Wuhan strain of SARS-CoV-2 we longitudinally analyzed changes in humoral and cellular immunity upon early and late convalescence. Antibody neutralization capacity was measured by surrogate virus neutralization test and cellular responses were investigated with 31-colour spectral flow cytometry. Spike-specific, isotype-switched B cells developed already during the disease phase, showed a memory phenotype and did not decrease in numbers even during late convalescence. Otherwise, no long-lasting perturbations of the immune compartment following COVID-19 clearance were observed. During convalescence anti-Spike (S1) IgG antibodies strongly decreased in all patients. We detected neutralizing antibodies against the Wuhan strain as well as the Alpha and Delta but not against the Beta, Gamma or Omicron variants for up to 7 months post COVID-19. Furthermore, correlation analysis revealed a strong association between sera anti-S1 IgG titers and their neutralization capacity against the Wuhan strain as well as Alpha and Delta. Overall, our data suggest that even 7 month after the clearance of COVID-19 many patients possess a protective layer of immunity, indicated by the persistence of Spike-specific memory B cells and by the presence of neutralizing antibodies against the Alpha and Delta variants. However, lack of neutralizing antibodies against the Beta, Gamma and Omicron variants even during the peak response is of major concern as this indicates viral evasion of the humoral immune response.

COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Convalescence , Humans , Immunity, Humoral , Immunoglobulin G , Prospective Studies , Spike Glycoprotein, Coronavirus/genetics
Cell Mol Immunol ; 18(4): 936-944, 2021 04.
Article in English | MEDLINE | ID: covidwho-899921


Neutralizing antibodies targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) block severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into cells via surface-expressed angiotensin-converting enzyme 2 (ACE2). We used a surrogate virus neutralization test (sVNT) and SARS-CoV-2 S protein-pseudotyped vesicular stomatitis virus (VSV) vector-based neutralization assay (pVNT) to assess the degree to which serum antibodies from coronavirus disease 2019 (COVID-19) convalescent patients interfere with the binding of SARS-CoV-2 S to ACE2. Both tests revealed neutralizing anti-SARS-CoV-2 S antibodies in the sera of ~90% of mildly and 100% of severely affected COVID-19 convalescent patients. Importantly, sVNT and pVNT results correlated strongly with each other and to the levels of anti-SARS-CoV-2 S1 IgG and IgA antibodies. Moreover, levels of neutralizing antibodies correlated with the duration and severity of clinical symptoms but not with patient age. Compared to pVNT, sVNT is less sophisticated and does not require any biosafety labs. Since this assay is also much faster and cheaper, sVNT will not only be important for evaluating the prevalence of neutralizing antibodies in a population but also for identifying promising plasma donors for successful passive antibody therapy.

Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/immunology , Spike Glycoprotein, Coronavirus/immunology , Adult , Aged , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/blood , Cell Line , Convalescence , Female , Humans , Immunoglobulin A/blood , Immunoglobulin G/blood , Male , Middle Aged , Neutralization Tests/methods
EBioMedicine ; 57: 102885, 2020 Jul.
Article in English | MEDLINE | ID: covidwho-633885


BACKGROUND: Elucidating the role of T cell responses in COVID-19 is of utmost importance to understand the clearance of SARS-CoV-2 infection. METHODS: 30 hospitalized COVID-19 patients and 60 age- and gender-matched healthy controls (HC) participated in this study. We used two comprehensive 11-colour flow cytometric panels conforming to Good Laboratory Practice and approved for clinical diagnostics. FINDINGS: Absolute numbers of lymphocyte subsets were differentially decreased in COVID-19 patients according to clinical severity. In severe disease (SD) patients, all lymphocyte subsets were reduced, whilst in mild disease (MD) NK, NKT and γδ T cells were at the level of HC. Additionally, we provide evidence of T cell activation in MD but not SD, when compared to HC. Follow up samples revealed a marked increase in effector T cells and memory subsets in convalescing but not in non-convalescing patients. INTERPRETATION: Our data suggest that activation and expansion of innate and adaptive lymphocytes play a major role in COVID-19. Additionally, recovery is associated with formation of T cell memory as suggested by the missing formation of effector and central memory T cells in SD but not in MD. Understanding T cell-responses in the context of clinical severity might serve as foundation to overcome the lack of effective anti-viral immune response in severely affected COVID-19 patients and can offer prognostic value as biomarker for disease outcome and control. FUNDING: Funded by State of Lower Saxony grant 14-76,103-184CORONA-11/20 and German Research Foundation, Excellence Strategy - EXC2155"RESIST"-Project ID39087428, and DFG-SFB900/3-Project ID158989968, grants SFB900-B3, SFB900-B8.

Betacoronavirus/immunology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Coronavirus Infections/immunology , Lymphocyte Activation/immunology , Pneumonia, Viral/immunology , Adult , Aged , Aged, 80 and over , Biomarkers , CD4-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/cytology , COVID-19 , Female , Humans , Immunologic Memory/immunology , Lymphocyte Count , Male , Middle Aged , Pandemics , Prognosis , SARS-CoV-2 , Severity of Illness Index , Young Adult