Superior immunity that allows neutralization of all SARS-CoV-2 variants of concern develops in COVID-19 convalescents and naïve individuals after three vaccinations

Infection-neutralizing antibody responses after SARS-CoV-2 infection or COVID-19 vaccination are an essential part of antiviral immunity. This immune protection is challenged by the occurrence of SARS-CoV-2 variants of concern (VoCs) with immune escape properties, such as omicron (B.1.1.529) that is rapidly spreading worldwide. Here, we report neutralizing antibody dynamics in a longitudinal cohort of COVID-19 convalescent and naïve individuals vaccinated with mRNA BNT162b2 by quantifying anti-SARS-CoV-2-spike antibodies and determining their avidity and neutralization capacity. A superior infection-neutralizing capacity against all VoCs, including omicron, developed by either two vaccinations of convalescents, or a third vaccination or breakthrough infection of twice-vaccinated naïve individuals. These three consecutive spike antigen exposures resulted in an increasing neutralization capacity per anti-spike antibody unit and were paralleled by stepwise increases in antibody avidity. In conclusion, an infection/vaccination-induced hybrid immunity or a triple immunization induces high-quality antibodies resulting in superior neutralization capacity against VoCs, including omicron.

Interdependencies between cellular and humoral immune responses in heterologous and homologous SARS-CoV-2 vaccination

Background: Homologous and heterologous SARS-CoV-2-vaccinations yield different spike protein-directed humoral and cellular immune responses. However, their interdependencies remain elusive. Methods: COV-ADAPT is a prospective, observational cohort study of 417 healthcare workers who received homologous vaccination with Astra (ChAdOx1-S; AstraZeneca) or BNT (BNT162b2; Biontech/Pfizer) or heterologous vaccination with Astra/BNT. We assessed the humoral (anti-spike-RBD-IgG, neutralizing antibodies, antibody avidity) and cellular (spike-induced T cell interferon-y release) immune response in blood samples up to 2 weeks before (T1) and 2 to 12 weeks following secondary immunization (T2). Findings: Initial vaccination with Astra resulted in lower anti-spike-RBD-IgG responses compared to BNT (70+/-114 vs. 226+/-279 BAU/ml, p<0.01) at T1, whereas T cell activation did not differ significantly. Booster vaccination with BNT proved superior to Astra at T2 (anti-spike-RBD-IgG: Astra/BNT 2387+/-1627 and BNT/BNT 3202+/-2184 vs. Astra/Astra 413+/-461 BAU/ml, both p<0.001; spike-induced T cell interferon-y; release: Astra/BNT 5069+/-6733 and BNT/BNT 4880+/-7570 vs. Astra/Astra 1152+/-2243 mIU/ml, both p<0.001). No significant differences were detected between BNT-boostered groups at T2. For Astra, we observed no booster effect on T cell activation. We found associations between anti-spike-RBD-IgG levels (Astra/BNT and BNT/BNT) and T cell responses (Astra/Astra and Astra/BNT) from T1 to T2. There were also links between levels of anti-spike-RBD-IgG and T cell at both time points (all groups combined). All regimes yielded neutralizing antibodies and increased antibody avidity at T2. Interpretation: Interdependencies between humoral and cellular immune responses differ between common SARS-CoV-2 vaccination regimes. T cell activation is unlikely to compensate for poor humoral responses. Funding: Deutsche Forschungsgemeinschaft (DFG), ER723/3-1

Efficacy of anti-SARS-CoV-2 mRNA vaccine in systemic autoimmune disorders: induction of high avidity and neutralising anti-RBD antibodies

ObjectivesIn patients with systemic autoimmune rheumatic disorders (SARDs), vaccination with SARS-CoV-2 mRNA vaccines has been proposed. The aim of this study is to evaluate the immune response elicited by vaccination with mRNA vaccine, testing IgM, IgA and IgG antibodies to SARS-CoV-2 receptor-binding domain (RBD) and measuring neutralising antibodies.MethodsIgG, IgM and IgA anti-RBD antibodies were measured in 101 patients with SARDs. Antibodies inhibiting the interaction between RBD and ACE2 were evaluated. Antibody avidity was tested in a chaotropic ELISA using urea. Twenty-one healthcare workers vaccinated with mRNA vaccine served as control group.ResultsAnti-RBD IgG and IgA were produced after the first dose (69% and 64% of the patients) and after the boost (93% and 83%). Antibodies inhibiting the interaction of RBD with ACE2 were detectable in 40% of the patients after the first dose and 87% after boost, compared with 100% in healthy controls (p<0.01). Abatacept and mycophenolate had an impact on the titre of IgG anti-RBD antibodies (p<0.05 and p<0.005, respectively) and on the amount of neutralising antibodies. No effect of other therapies was observed. Vaccinated patients produce high avidity antibodies, as healthy controls.ConclusionsThese data show that double-dose vaccination induced in patients with SARDs anti-RBD IgG and IgA antibodies in amounts not significantly different from controls, and, most interestingly, characterised by high avidity and endowed with neutralising activity.

A Dual-Antigen SARS-CoV-2 Serological Assay Reflects Antibody Avidity

Serial antibody measurements using an array of SARS-CoV-2 immunoassays have demonstrated differing kinetics among assay platforms (1).…

A cohort of 222 anti-CD20 treated patients with multiple sclerosis followed through the COVID-19 pandemic: Attenuated humoral but robust cellular immune responses after vaccination and infection

Importance: Data on immune responses following SARS-CoV-2 vaccinations/infections and on detection rate of SARS-CoV-2 infections in anti-CD20 treated patients with multiple sclerosis (pwMS) are important for guiding management of pwMS during the current SARS-CoV-2 pandemic. Objective: To analyze humoral and cellular immune responses to SARS-CoV-2 vaccinations/infections and to determine the detection rate of SARS-CoV-2 infections in anti-CD20 treated pwMS. Design: Prospective single-center cohort study from March 2020 to August 2021. Setting: MS referral center, Charite - Universitaetsmedizin Berlin, Germany. Participants: 222 consecutive pwMS (128 [57.7%] female, median [range] age 39 [17-81] years). 181 patients were on anti-CD20 therapy at study inclusion, 41 began anti-CD20 therapy during the study. Hospital employees (HE, n=19) served as controls. Exposures: pwMS were exposed to anti-CD20 therapy for 169.5 patient years. 51 patients under anti-CD20 treatment, 14 patients before anti-CD20 treatment, and 19 HE were vaccinated twice against SARS-CoV-2. Main outcomes: SARS-CoV-2 spike protein immunoglobulin (Ig)G (ELISA and immunofluorescence), IgA (ELISA), IgG to four recombinant SARS-CoV-2 antigens (solid phase immunoassay), neutralizing capacity of SARS-CoV-2 antibodies (plaque reduction neutralization test), SARS-CoV-2 IgG avidity (modified ELISA), and SARS-CoV-2 specific T cells (interferon-γ release assay). Results: Following two SARS-CoV-2 vaccinations, median (IQR) levels of SARS-CoV-2 spike protein IgG (OD ratio: 1.2 [0.1-5.1] vs. 9.0 [6.8-9.9] vs. 8.8 [8.0-9.4], p<0.0001), neutralizing capacity (PRNT50 Titer: 40 [0-80] vs. 640 [80-640] vs. 640 [320-640], p≤0.006), and antibody avidity (43.6% [14.8-54.6%] vs. 84.1% [53.1-86.8%] vs. 89.7 [76.8-93.4%], p≤0.003) were lower in anti-CD20 treated pwMS than in pwMS before initiation of anti-CD20 therapy and in HE. All anti-CD20 treated pwMS vaccinated twice developed SARS-CoV-2 specific T cells, whose levels did not differ from those of pwMS before initiation of anti-CD20 therapy and HE. SARS-CoV-2 IgG levels (r=0.42, p=0.002) and antibody avidity (r=0.70, p<0.001) increased with time between anti-CD20 infusion and second vaccination. The detection rate of SARS-CoV-2 infections in anti-CD20 treated pwMS (2.36/100 patient years) was similar to that of RT-PCR confirmed SARS-CoV-2 cases in the general Berlin population (3.75/100 person years) during the study period. Interpretation: These findings are relevant for treatment decisions as well as management of SARS-CoV-2 vaccinations in pwMS.

Defective neutralizing antibody response to SARS-CoV-2 in vaccinated dialysis patients

Patients on dialysis are at risk of severe course of SARS-CoV-2 infection. Understanding the neutralizing activity and coverage of SARS-CoV-2 variants of vaccine-elicited antibodies is required to guide prophylactic and therapeutic COVID-19 interventions in this frail population. By analyzing plasma samples from 130 hemodialysis (HD) and 13 peritoneal dialysis patients after two doses of BNT162b2 or mRNA-1273 vaccines, we found that 35% of the patients had low-level or undetectable IgG antibodies to SARS-CoV-2 Spike (S). Neutralizing antibodies against the vaccine-matched SARS-CoV-2 and Delta variant were low or undetectable in 49% and 77% of patients, respectively, and were further reduced against other emerging variants. The fraction of non-responding patients was higher in SARS-CoV-2-naive HD patients immunized with BNT162b2 (66%) than those immunized with mRNA-1273 (23%). The reduced neutralizing activity correlated with low antibody avidity, consistent with a delayed affinity maturation of SARS-CoV-2 S-specific B cells. These data indicate that dialysis patients should be considered for an additional boost and other therapeutic strategies, including early immunotherapy with monoclonal antibodies.

Longitudinal Study of SARS-CoV-2 Antibody Characteristics Using Label-Free Immunoassays

Introduction/Objective Since the start of the COVID-19 pandemic, much research has focused on the kinetics and magnitude of humoral immune response. With the advantages of monitoring real-time immunoreactions, label-free immunoassay (LFIA) is becoming a powerful tool in serology studies. We have developed LFIAs to measure SARS- CoV-2 antibody avidity and neutralization activity in a cohort of COVID-19 patients and determine if they correlate with antibody concentration. Serial serum samples collected from mild to severe COVID-19 patients were measured out to 8 months post-symptom onset to determine the durability of the neutralizing antibody response. Methods/Case Report Based on thin-film interferometry technology, we established a label-free IgG avidity assay and a label-free surrogate virus neutralization test (LF-sVNT). For measurement, sensing probes pre-coated with receptor-binding domain (RBD) of SARS-CoV-2 spike protein are applied to serum samples containing SARS-CoV-2 antibodies. The label-free IgG avidity assay measures the binding strength between RBD and IgG under urea dissociation. The LF-sVNT analyzes the binding ability of RBD to ACE2 after neutralizing RBD with antibodies. Results (if a Case Study enter NA) IgG avidity indices and neutralizing antibody titers (IC50) were determined from serum samples (n=246) from COVID-19 patients (n=113). IgG concentrations were measured using a fluorescent immunoassay. The neutralizing antibody titers showed a weak correlation with IgG concentrations and no correlation with IgG avidity indices. Over the time course up to 8 months post-symptom onset, IgG concentrations and neutralizing antibody titers presented similar trends: an initial rise, plateau and then in some cases a gradual decline after 40 days. The IgG avidity indices, in the same cases, plateaued after the initial rise. Conclusion The results demonstrated that LFIA could be used an excellent solution in the determination of SARS- CoV-2 antibody characteristics. The study found that IgG concentration and neutralizing antibody titer declined over time, while IgG avidity index remained constant after reaching a plateau. The decline of antibody neutralization activity can be attributed to the reduction in antibody quantity rather than the deterioration of antibody quality, as measured by antibody avidity.

Assessment of avidity related to IgG subclasses in SARS-CoV-2 Brazilian infected patients

SARS-CoV-2 is considered a global emergency, resulting in an exacerbated crisis in the health public in the world. Although there are advances in vaccine development, it is still limited for many countries. On the other hand, an immunological response that mediates protective immunity or indicates that predict disease outcome in SARS-CoV-2 infection remains undefined. This work aimed to assess the antibody levels, avidity, and subclasses of IgG to RBD protein, in symptomatic patients with severe and mild forms of COVID-19 in Brazil using an adapted in-house RBD-IgG ELISA. The RBD IgG-ELISA showed 100% of specificity and 94.3% of sensibility on detecting antibodies in the sera of hospitalized patients. Patients who presented severe COVID-19 had higher anti-RBD IgG levels compared to patients with mild disease. Additionally, most patients analyzed displayed low antibody avidity, with 64.4% of the samples of patients who recovered from the disease and 84.6% of those who died in this avidity range. Our data also reveals an increase of IgG1 and IgG3 levels since the 8th day after symptoms onset, while IgG4 levels maintained less detectable during the study period. Surprisingly, patients who died during 8–14 and 15–21 days also showed higher anti-RBD IgG4 levels in comparison with the recovered (P < 0.05), suggesting that some life-threatening patients can elicit IgG4 to RBD antibody response in the first weeks of symptoms onset. Our findings constitute the effort to clarify IgG antibodies' kinetics, avidity, and subclasses against SARS-CoV-2 RBD in symptomatic patients with COVID-19 in Brazil, highlighting the importance of IgG antibody avidity in association with IgG4 detection as tool laboratory in the follow-up of hospitalized patients with more significant potential for life-threatening.

Chronic tick-borne encephalitis

Статья посвящена эпилепсии Кожевникова, одному из наиболее распространенных и по сути патогномоничных проявлений хронического течения клещевого энцефалита. Описаны стадийность в ее развитии, типы течения сформировавшейся кожевниковской эпилепсии, подходы к терапии. В статье представлен уникальный по продолжительности наблюдения случай хронического клещевого энцефалита (ХКЭ) (47 лет от начала заболевания и свыше 30 лет после вакцинотерапии). Показано, что замедленное развитие тяжелой неврологической симптоматики, прогрессирование болезни происходят на фоне дисиммуноглобулинемии. Штамм, выделенный от пациентки, обладал высокой нейровирулентностью для белых мышей, был высоконейроинвазивным, показал принадлежность к сибирскому подтипу вируса клещевого энцефалита. По мере прогрессирования ХКЭ развивался полиштаммовый иммунный ответ и напряженный иммунитет с высокой авидностью антител (через 30-32 года после вакцинотерапии). В неврологическом статусе – характерные постэнцефалитические изменения с элементами кортикальной моторной эпилепсии. Существенного когнитивного дефекта не было выявлено. The article is devoted to Kozhevnikov's epilepsy, one of the most common and, in fact, pathognomonic manifestations of the chronic course of tick-borne encephalitis. The stages in its development, the types of the course of the formed Kozhevnikovskaya epilepsy, and approaches to therapy are described. This material presents a unique case of chronic tick-borne encephalitis (TBE) (47 years from the beginning of the disease and more than 30 years after vaccination). It is shown that the delayed development of severe neurological symptoms and disease progression occur against the background of dysimmunoglobulinemia. The strain isolated from the patient had high neurovirulence for white mice, was highly neuroinvasive, and belong to the Siberian subtype of tick-borne encephalitis virus (TBEV). As TBE progressed, a polystrain immune response and a stressed immune response with high antibody avidity developed (30-32 years after vaccination). In the neurological status – pecular postencephalitic changes with elements of cortical motor epilepsy. No significant cognitive defect was detected.