Secondary sclerosing cholangitis in patients with COVID-19 ARDS-a specific entity associated with high mortality?

Introduction SSC-CIP (secondary sclerosing cholangitis in critically ill patients) is characterized by biliary tract destruction after long intensive care treatment. Hypotension and vasopressor therapy are main risk factors. Increased prevalence of SSC-CIP occurred in patients with COVID-19 ARDS that were treated by endoscopic retrograde cholangiography (ERC). Aims The aim of the study was to analyze clinical, laboratory, microbiological and endoscopic fndings of patients with SSC-CIP with COVID-19 ARDS. Methods Data of 17 patients with SSC-CIP with COVID-19 ARDS between February 2020 and August 2022 were analyzed retrospectively. The focus was on endoscopic fndings, laboratory and microbiological values and on clinical parameters and potential risk factors during COVID-19 ARDS. Results 14 male and 3 female patients were included. The mean age was 60 years (range 40-76). All patients were mechanically ventilated, 11 patients were treated with ECMO. All patients required catecholamine therapy but only low dosed when compared with other septic conditions. On average 2.6 ERCs were performed. Biliary casts were found in 94 % of the patients and rarefcation of the intrahepatic bile ducts in 50 %. Bile duct stenosis was detected in 3 patients. Casts were extracted and stenoses were dilated. 13 patients died, 4 patients are in follow-up with repeated endoscopic intervention and re-evaluation in regard to liver transplantation. Discussion Mortality rate in patients with SSC-CIP with COVID-19 ARDS is high. Vasopressor therapy and hypotension was not prominent in this cohort. Endo-scopic treatment may improve liver function, however these patients must be evaluated for liver transplantation.

Antibody binding and ACE2 binding inhibition is significantly reduced for both the BA1 and BA2 omicron variants.

BACKGROUND: The rapid emergence of the omicron variant and its large number of mutations led to its classification as a variant of concern (VOC) by the WHO. Subsequently, omicron evolved into distinct sublineages (e.g. BA1 and BA2), which currently represent the majority of global infections. Initial studies of the neutralizing response towards BA1 in convalescent and vaccinated individuals showed a substantial reduction. METHODS: We assessed antibody (IgG) binding, ACE2 (Angiotensin-Converting Enzyme 2) binding inhibition, and IgG binding dynamics for the omicron BA1 and BA2 variants compared to a panel of VOC/VOIs, in a large cohort (n = 352) of convalescent, vaccinated, and infected and subsequently vaccinated individuals. RESULTS: While omicron was capable efficiently binding to ACE2, antibodies elicited by infection or immunization showed reduced binding capacities and ACE2 binding inhibition compared to WT. Whereas BA1 exhibited less IgG binding compared to BA2, BA2 showed reduced inhibition of ACE2 binding. Among vaccinated samples, antibody binding to omicron only improved after administration of a third dose. CONCLUSION: omicron BA1 and BA2 can still efficiently bind to ACE2, while vaccine/infection-derived antibodies can bind omicron. The extent of the mutations within both variants prevent a strong inhibitory binding response. As a result, both omicron variants are able to evade control by pre-existing antibodies.

Knowledge4COVID-19: A semantic-based approach for constructing a COVID-19 related knowledge graph from various sources and analyzing treatments' toxicities.

In this paper, we present Knowledge4COVID-19, a framework that aims to showcase the power of integrating disparate sources of knowledge to discover adverse drug effects caused by drug-drug interactions among COVID-19 treatments and pre-existing condition drugs. Initially, we focus on constructing the Knowledge4COVID-19 knowledge graph (KG) from the declarative definition of mapping rules using the RDF Mapping Language. Since valuable information about drug treatments, drug-drug interactions, and side effects is present in textual descriptions in scientific databases (e.g., DrugBank) or in scientific literature (e.g., the CORD-19, the Covid-19 Open Research Dataset), the Knowledge4COVID-19 framework implements Natural Language Processing. The Knowledge4COVID-19 framework extracts relevant entities and predicates that enable the fine-grained description of COVID-19 treatments and the potential adverse events that may occur when these treatments are combined with treatments of common comorbidities, e.g., hypertension, diabetes, or asthma. Moreover, on top of the KG, several techniques for the discovery and prediction of interactions and potential adverse effects of drugs have been developed with the aim of suggesting more accurate treatments for treating the virus. We provide services to traverse the KG and visualize the effects that a group of drugs may have on a treatment outcome. Knowledge4COVID-19 was part of the Pan-European hackathon#EUvsVirus in April 2020 and is publicly available as a resource through a GitHub repository and a DOI.

The Bangabandhu Tariff—Improving Access to Sustainable Electricity and Co-Benefits of Climate Change Through Community Power Purchase Agreements

The COVID-19 pandemic has long moved beyond a global health crisis and morphing into a social and economic crisis, which combined with climate change threats, can seriously jeopardize the advancements that have been made to date towards the Sustainable Development Goals (SDGs), globally and in particular in Bangladesh. Our collective actions towards economic recovery and building resilience against future pandemics represent a chance to pave the way for a more sustainable future. At its center lies sustainable energy access as defined in SDG 7 and a key enabler for the majority of the remaining SDGs. SDG 7 is essential to build future resilience. Public energy utilities need to recover from a dramatic shortfall in revenues, households, and businesses have to overcome financing challenges to be able to tap into significant and inclusive growth opportunities. At the same time, it is important that central grid expansion, or the threat thereof, does not negatively affect or prevent decentralized and decarbonized solutions. C-19 has also unearthed several shortcomings in our existing systems. The future of energy is fueled by the 5Ds: decarbonization, decentralization, democratization, digitization, and disruption. The 4th Industrial Revolution has provided us with the right tools to start turning this future vision of the power sector into a reality today. In this paper, we are proposing an innovation policy, the Bangabandhu Tariff, for both a greener and a more inclusive recovery based on smart IoT devices enabling the interconnection of remote solar home systems and their collective feed-in to the national grid. This policy is based on Community Power Purchase Agreements an effective tool towards a resilient and sustainable recovery, the development of national utilities while empowering decentralized renewable energy prosumers with a financial incentive for electricity generation and storage usage to help power the nation starting at the base of the pyramid. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Longitudinal cellular and humoral immune responses after triple BNT162b2 and fourth full-dose mRNA-1273 vaccination in haemodialysis patients.

Haemodialysis patients respond poorly to vaccination and continue to be at-risk for severe COVID-19. Therefore, dialysis patients were among the first for which a fourth COVID-19 vaccination was recommended. However, targeted information on how to best maintain immune protection after SARS-CoV-2 vaccinations in at-risk groups for severe COVID-19 remains limited. We provide, to the best of our knowledge, for the first time longitudinal vaccination response data in dialysis patients and controls after a triple BNT162b2 vaccination and in the latter after a subsequent fourth full-dose of mRNA-1273. We analysed systemic and mucosal humoral IgG responses against the receptor-binding domain (RBD) and ACE2-binding inhibition towards variants of concern including Omicron and Delta with multiplex-based immunoassays. In addition, we assessed Spike S1-specific T-cell responses by interferon γ release assay. After triple BNT162b2 vaccination, anti-RBD B.1 IgG and ACE2 binding inhibition reached peak levels in dialysis patients, but remained inferior compared to controls. Whilst we detected B.1-specific ACE2 binding inhibition in 84% of dialysis patients after three BNT162b2 doses, binding inhibition towards the Omicron variant was only detectable in 38% of samples and declining to 16% before the fourth vaccination. By using mRNA-1273 as fourth dose, humoral immunity against all SARS-CoV-2 variants tested was strongly augmented with 80% of dialysis patients having Omicron-specific ACE2 binding inhibition. Modest declines in T-cell responses in dialysis patients and controls after the second vaccination were restored by the third BNT162b2 dose and significantly increased by the fourth vaccination. Our data support current advice for a four-dose COVID-19 immunisation scheme for at-risk individuals such as haemodialysis patients. We conclude that administration of a fourth full-dose of mRNA-1273 as part of a mixed mRNA vaccination scheme to boost immunity and to prevent severe COVID-19 could also be beneficial in other immune impaired individuals. Additionally, strategic application of such mixed vaccine regimens may be an immediate response against SARS-CoV-2 variants with increased immune evasion potential.

Longitudinal cellular and humoral immune responses after triple BNT162b2 and fourth full-dose mRNA-1273 vaccination in haemodialysis patients (preprint)

Background Haemodialysis patients are at-risk for severe COVID-19 and were among the first to receive a fourth COVID-19 vaccination. Methods We analysed humoral responses by multiplex-based IgG measurements against the receptor-binding domain (RBD) and ACE2-binding inhibition towards variants of concern including Omicron in haemodialysis patients and controls after triple BNT162b2 vaccination and in dialysis patients after a fourth full-dose of mRNA-1273. T-cell responses were assessed by interferon gamma release assay. Findings After triple BNT162b2 vaccination, anti-RBD B.1 IgG and ACE2 binding inhibition reached peak levels in dialysis patients, but remained inferior compared to controls. Whilst we detected B.1-specific ACE2 binding inhibition in 84% of dialysis patients after three BNT162b2 doses, binding inhibition towards the Omicron variant was only 38% and declining to 16% before the fourth vaccination. By using mRNA-1273 as fourth dose, humoral immunity against all SARS-CoV-2 variants tested was strongly augmented with 80% of dialysis patients having Omicron-specific ACE2 binding inhibition. Modest declines in T-cell responses in dialysis patients and controls after the second vaccination were restored by the third BNT162b2 dose and significantly increased by the fourth vaccination. Conclusions A fourth full-dose mRNA-1273 after triple BNT162b2 vaccination in haemodialysis patients leads to efficient humoral responses against Omicron. Our data support current national recommendation and suggest that other immune-impaired individuals may benefit from this mixed mRNA vaccination regimen. Funding Initiative and Networking Fund of the Helmholtz Association of German Research Centres, EU Horizon 2020 research and innovation program, State Ministry of Baden-Wuerttemberg for Economic Affairs, Labour and Tourism, European Regional Development Fund

COVID-19 patient serum less potently inhibits ACE2-RBD binding for various SARS-CoV-2 RBD mutants.

As global vaccination campaigns against SARS-CoV-2 proceed, there is particular interest in the longevity of immune protection, especially with regard to increasingly infectious virus variants. Neutralizing antibodies (Nabs) targeting the receptor binding domain (RBD) of SARS-CoV-2 are promising correlates of protective immunity and have been successfully used for prevention and therapy. As SARS-CoV-2 variants of concern (VOCs) are known to affect binding to the ACE2 receptor and by extension neutralizing activity, we developed a bead-based multiplex ACE2-RBD inhibition assay (RBDCoV-ACE2) as a highly scalable, time-, cost-, and material-saving alternative to infectious live-virus neutralization tests. By mimicking the interaction between ACE2 and the RBD, this serological multiplex assay allows the simultaneous analysis of ACE2 binding inhibition to the RBDs of all SARS-CoV-2 VOCs and variants of interest (VOIs) in a single well. Following validation against a classical virus neutralization test and comparison of performance against a commercially available assay, we analyzed 266 serum samples from 168 COVID-19 patients of varying severity. ACE2 binding inhibition was reduced for ten out of eleven variants examined compared to wild-type, especially for those displaying the E484K mutation such as VOCs beta and gamma. ACE2 binding inhibition, while highly individualistic, positively correlated with IgG levels. ACE2 binding inhibition also correlated with disease severity up to WHO grade 7, after which it reduced.

Knowledge4COVID-19: A Semantic-based Approach for Constructing a COVID-19 related Knowledge Graph from Various Sources and Analysing Treatments' Toxicities (preprint)

In this paper, we present Knowledge4COVID-19, a framework that aims to showcase the power of integrating disparate sources of knowledge to discover adverse drug effects caused by drug-drug interactions among COVID-19 treatments and pre-existing condition drugs. Initially, we focus on constructing the Knowledge4COVID-19 knowledge graph (KG) from the declarative definition of mapping rules using the RDF Mapping Language. Since valuable information about drug treatments, drug-drug interactions, and side effects is present in textual descriptions in scientific databases (e.g., DrugBank) or in scientific literature (e.g., the CORD-19, the Covid-19 Open Research Dataset), the Knowledge4COVID-19 framework implements Natural Language Processing. The Knowledge4COVID-19 framework extracts relevant entities and predicates that enable the fine-grained description of COVID-19 treatments and the potential adverse events that may occur when these treatments are combined with treatments of common comorbidities, e.g., hypertension, diabetes, or asthma. Moreover, on top of the KG, several techniques for the discovery and prediction of interactions and potential adverse effects of drugs have been developed with the aim of suggesting more accurate treatments for treating the virus. We provide services to traverse the KG and visualize the effects that a group of drugs may have on a treatment outcome. Knowledge4COVID-19 was part of the Pan-European hackathon#EUvsVirus in April 2020 and is publicly available as a resource through a GitHub repository (https://github.com/SDM-TIB/Knowledge4COVID-19) and a DOI (https://zenodo.org/record/4701817#.YH336-8zbol).

Diminishing Immune Responses against Variants of Concern in Dialysis Patients 4 Months after SARS-CoV-2 mRNA Vaccination.

Patients undergoing chronic hemodialysis were among the first to receive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations because of their increased risk for severe coronavirus disease and high case-fatality rates. By using a previously reported cohort from Germany of at-risk hemodialysis patients and healthy donors, where antibody responses were examined 3 weeks after the second vaccination, we assessed systemic cellular and humoral immune responses in serum and saliva 4 months after vaccination with the Pfizer-BioNTech BNT162b2 vaccine using an interferon-γ release assay and multiplex-based IgG measurements. We further compared neutralization capacity of vaccination-induced IgG against 4 SARS-CoV-2 variants of concern (Alpha, Beta, Gamma, and Delta) by angiotensin-converting enzyme 2 receptor-binding domain competition assay. Sixteen weeks after second vaccination, compared with 3 weeks after, cellular and humoral responses against the original SARS-CoV-2 isolate and variants of concern were substantially reduced. Some dialysis patients even had no detectable B- or T-cell responses.

Comparative Magnitude and Persistence of Humoral SARS-CoV-2 Vaccination Responses in the Adult Population in Germany.

Recent increases in SARS-CoV-2 infections have led to questions about duration and quality of vaccine-induced immune protection. While numerous studies have been published on immune responses triggered by vaccination, these often focus on studying the impact of one or two immunisation schemes within subpopulations such as immunocompromised individuals or healthcare workers. To provide information on the duration and quality of vaccine-induced immune responses against SARS-CoV-2, we analyzed antibody titres against various SARS-CoV-2 antigens and ACE2 binding inhibition against SARS-CoV-2 wild-type and variants of concern in samples from a large German population-based seroprevalence study (MuSPAD) who had received all currently available immunisation schemes. We found that homologous mRNA-based or heterologous prime-boost vaccination produced significantly higher antibody responses than vector-based homologous vaccination. Ad26.CoV2S.2 performance was particularly concerning with reduced titres and 91.7% of samples classified as non-responsive for ACE2 binding inhibition, suggesting that recipients require a booster mRNA vaccination. While mRNA vaccination induced a higher ratio of RBD- and S1-targeting antibodies, vector-based vaccines resulted in an increased proportion of S2-targeting antibodies. Given the role of RBD- and S1-specific antibodies in neutralizing SARS-CoV-2, their relative over-representation after mRNA vaccination may explain why these vaccines have increased efficacy compared to vector-based formulations. Previously infected individuals had a robust immune response once vaccinated, regardless of which vaccine they received, which could aid future dose allocation should shortages arise for certain manufacturers. Overall, both titres and ACE2 binding inhibition peaked approximately 28 days post-second vaccination and then decreased.

Robust and durable serological response following pediatric SARS-CoV-2 infection.

The quality and persistence of children's humoral immune response following SARS-CoV-2 infection remains largely unknown but will be crucial to guide pediatric SARS-CoV-2 vaccination programs. Here, we examine 548 children and 717 adults within 328 households with at least one member with a previous laboratory-confirmed SARS-CoV-2 infection. We assess serological response at 3-4 months and 11-12 months after infection using a bead-based multiplex immunoassay for 23 human coronavirus antigens including SARS-CoV-2 and its Variants of Concern (VOC) and endemic human coronaviruses (HCoVs), and additionally by three commercial SARS-CoV-2 antibody assays. Neutralization against wild type SARS-CoV-2 and the Delta VOC are analysed in a pseudotyped virus assay. Children, compared to adults, are five times more likely to be asymptomatic, and have higher specific antibody levels which persist longer (96.2% versus 82.9% still seropositive 11-12 months post infection). Of note, symptomatic and asymptomatic infections induce similar humoral responses in all age groups. SARS-CoV-2 infection occurs independent of HCoV serostatus. Neutralization responses of children and adults are similar, although neutralization is reduced for both against the Delta VOC. Overall, the long-term humoral immune response to SARS-CoV-2 infection in children is of longer duration than in adults even after asymptomatic infection.

Biparatopic nanobodies protect mice from lethal challenge with SARS-CoV-2 variants of concern.

The ongoing COVID-19 pandemic and the emergence of new SARS-CoV-2 variants of concern (VOCs) requires continued development of effective therapeutics. Recently, we identified high-affinity neutralizing nanobodies (Nbs) specific for the receptor-binding domain (RBD) of SARS-CoV-2. Taking advantage of detailed epitope mapping, we generate two biparatopic Nbs (bipNbs) targeting a conserved epitope outside and two different epitopes inside the RBD:ACE2 interface. Both bipNbs bind all currently circulating VOCs with high affinities and are capable to neutralize cellular infection with VOC B.1.351 (Beta) and B.1.617.2 (Delta) in vitro. To assess if the bipNbs NM1267 and NM1268 confer protection against SARS-CoV-2 infection in vivo, human ACE2 transgenic mice are treated intranasally before infection with a lethal dose of SARS-CoV-2 B.1, B.1.351 (Beta) or B.1.617.2 (Delta). Nb-treated mice show significantly reduced disease progression and increased survival rates. Histopathological analyses further reveal a drastically reduced viral load and inflammatory response in lungs. These data suggest that both bipNbs are broadly active against a variety of emerging SARS-CoV-2 VOCs and represent easily applicable drug candidates.

Antibody binding and ACE2 binding inhibition is significantly reduced for the Omicron variant compared to all other variants of concern (preprint)

The rapid emergence of the Omicron variant and its large number of mutations has led to its classification as a variant of concern (VOC) by the WHO. Initial studies on the neutralizing response towards this variant within convalescent and vaccinated individuals have identified substantial reductions. However many of these sample sets used in these studies were either small, uniform in nature, or were compared only to wild-type (WT) or, at most, a few other VOC. Here, we assessed IgG binding, (Angiotensin-Converting Enzyme 2) ACE2 binding inhibition, and antibody binding dynamics for the omicron variant compared to all other VOC and variants of interest (VOI), in a large cohort of infected, vaccinated, and infected and then vaccinated individuals. While omicron was capable of binding to ACE2 efficiently, antibodies elicited by infection or immunization showed reduced IgG binding and ACE2 binding inhibition compared to WT and all VOC. Among vaccinated samples, antibody binding responses towards omicron were only improved following administration of a third dose. Overall, our results identify that omicron can still bind ACE2 while pre-existing antibodies can bind omicron. The extent of the mutations appear to inhibit the development of a neutralizing response, and as a result, omicron remains capable of evading immune control.

Comparative magnitude and persistence of SARS-CoV-2 vaccination responses on a population level in Germany (preprint)

Background While SARS-CoV-2 vaccinations were successful in decreasing COVID-19 caseloads, recent increases in SARS-CoV-2 infections have led to questions about duration and quality of the subsequent immune response. While numerous studies have been published on immune responses triggered by vaccination, these often focused on the initial peak response generated in specific population subgroups (e.g. healthcare workers or immunocompromised individuals) and have often only examined the effects of one or two different immunisation schemes. Methods and Findings We analysed serum samples from participants of a large German seroprevalence study (MuSPAD) who had received all available vaccines and dose schedules (mRNA-1273, BNT162b2, AZD1222, Ad26.CoV2S.2 or a combination of AZD1222 plus either mRNA-1273 or BNT162b2). Antibody titers against various SARS-CoV-2 antigens and ACE2 binding inhibition against SARS-CoV-2 wild-type and the Alpha, Beta, Gamma and Delta variants of concern were analysed using a previously published multiplex immunoassay MULTICOV-AB and an ACE2-RBD competition assay. Among the different vaccines and their dosing regimens, homologous mRNA-based or heterologous prime-boost vaccination produced significantly higher antibody responses than vector-based homologous vaccination. Ad26.CoV2S.2 performance was significantly reduced, even compared to AZD1222, with 91.67% of samples being considered non-responsive forACE2 binding inhibition. mRNA-based vaccination induced a higher ratio of RBD- and S1-targeting antibodies than vector-based vaccination, which resulted in an increased proportion of S2-targeting antibodies. Previously infected individuals had a robust immune response once vaccinated, regardless of which vaccine they received. When examining antibody kinetics post-vaccination after homologous immunisation regimens, both titers and ACE2 binding inhibition peaked approximately 28 days post-vaccination and then decreased as time increased. Conclusions As one of the first and largest population-based studies to examine vaccine responses for all currently available immunisation schemes in Germany, we found that homologous mRNA or heterologous vaccination elicited the highest immune responses. The high percentage of non-responders for Ad26.CoV2.S requires further investigation and suggests that a booster dose with an mRNA-based vaccine may be necessary. The high responses seen in recovered and vaccinated individuals could aid future dose allocation, should shortages arise for certain manufacturers. Given the role of RBD- and S1-specific antibodies in neutralising SARS-CoV-2, their relative over-representation after mRNA vaccination may explain why mRNA vaccines have an increased efficacy compared to vector-based formulations. Further investigation on these differences will be of particular interest for vaccine development and efficacy, especially for the next-generation of vector-based vaccines.

Reduced serum neutralization capacity against SARS-CoV-2 variants in a multiplex ACE2 RBD competition assay (preprint)

As global vaccination campaigns against SARS-CoV-2 proceed, there is emerging interest in the longevity of immune protection, especially with regard to increasingly infectious virus variants. Neutralizing antibodies (Nabs) targeting the receptor binding domain (RBD) of SARS-CoV-2 are promising correlates of protective immunity and have been successfully used for prevention and therapy. To assess neutralizing capacity, we developed a bead-based multiplex ACE2 RBD competition assay as a large scalable, time-, cost-, and material-saving alternative to infectious live-virus neutralization tests. By mimicking the interaction between ACE2 and RBD, this assay detects the presence of Nabs against SARS-CoV2 in serum. Using this multiplex approach allows the simultaneous analysis of Nabs against all SARS-CoV-2 variants of concern and variants of interest in a single well. Following validation, we analyzed 325 serum samples from 186 COVID-19 patients of varying severity. Neutralization capacity was reduced for all variants examined compared to wild-type, especially for those displaying the E484K mutation. The neutralizing immune response itself, while highly individualistic, positively correlates with IgG levels. Neutralization capacity also correlated with disease severity up to WHO grade 7, after which it reduced.

Diminishing immune responses against variants of concern in dialysis patients four months after SARS-CoV-2 mRNA vaccination (preprint)

Patients undergoing chronic hemodialysis were among the first to receive SARS-CoV-2 vaccinations due to their increased risk for severe COVID-19 disease and high case fatality rates. To date, there have been minimal longitudinal studies in hemodialysis patients to ascertain whether protection offered by vaccination is long-lasting. To assess how surrogates for protection changed over time, we examined both the humoral and cellular response in a previously reported cohort of at-risk hemodialysis patients and healthy donors, four months after their second dose of Pfizer BNT162b2. Compared to three weeks post-second vaccination, both cellular and humoral responses against the original SARS-CoV-2 isolate as well as variants of concern were significantly reduced, with some dialyzed individuals having no B- or T-cell response. Our data strongly support the need for a third booster in hemodialysis patients and potentially other at-risk individuals.

Cellular and humoral immunogenicity of a SARS-CoV-2 mRNA vaccine in patients on haemodialysis.

BACKGROUND: Patients with chronic renal insufficiency on maintenance haemodialysis face an increased risk of COVID-19 induced mortality and impaired vaccine responses. To date, only a few studies have addressed SARS-CoV-2 vaccine elicited immunity in this immunocompromised population. METHODS: We assessed immunogenicity of the mRNA vaccine BNT162b2 in at-risk dialysis patients and characterised systemic cellular and humoral immune responses in serum and saliva using interferon γ release assay and multiplex-based cytokine and immunoglobulin measurements. We further compared binding capacity and neutralization efficacy of vaccination-induced immunoglobulins against emerging SARS-CoV-2 variants Alpha, Beta, Epsilon and Cluster 5 by ACE2-RBD competition assay. FINDINGS: Patients on maintenance haemodialysis exhibit detectable but variable cellular and humoral immune responses against SARS-CoV-2 and variants of concern after a two-dose regimen of BNT162b2. Although vaccination-induced immunoglobulins were detectable in saliva and plasma, both anti-SARS-CoV-2 IgG and neutralization efficacy was reduced compared to a vaccinated non-dialysed control population. Similarly, T-cell mediated interferon γ release after stimulation with SARS-CoV-2 spike peptides was significantly diminished. INTERPRETATION: Quantifiable humoral and cellular immune responses after BNT162b2 vaccination in individuals on maintenance haemodialysis are encouraging, but urge for longitudinal follow-up to assess longevity of immunity. Diminished virus neutralization and interferon γ responses in the face of emerging variants of concern may favour this at-risk population for re-vaccination using modified vaccines at the earliest opportunity. FUNDING: Initiative and Networking Fund of the Helmholtz Association of German Research Centres, EU Horizon 2020 research and innovation program, State Ministry of Baden-Württemberg for Economic Affairs, Labour and Tourism.

A broadly neutralizing biparatopic Nanobody protects mice from lethal challenge with SARS-CoV-2 variants of concern (preprint)

The ongoing COVID-19 pandemic and the frequent emergence of new SARS-CoV-2 variants of concern (VOCs), requires continued development of fast and effective therapeutics. Recently, we identified high-affinity neutralizing nanobodies (Nb) specific for the receptor-binding domain (RBD) of SARS-CoV-2, which are now being used as biparatopic Nbs (bipNbs) to investigate their potential as future drug candidates. Following detailed in vitro characterization, we chose NM1267 as the most promising candidate showing high affinity binding to several recently described SARS-CoV-2 VOCs and strong neutralizing capacity against a patient isolate of B.1.351 (Beta). To assess if bipNb NM1267 confers protection against SARS-CoV-2 infection in vivo, human ACE2 transgenic mice were treated by intranasal route before infection with a lethal dose of SARS-CoV-2. NM1267-treated mice showed significantly reduced disease progression, increased survival rates and secreted less infectious virus via their nostrils. Histopathological analyses and in situ hybridization further revealed a drastically reduced viral load and inflammatory response in lungs of NM1267-treated mice. These data suggest, that bipNb NM1267 is a broadly active and easily applicable drug candidate against a variety of emerging SARS-CoV-2 VOCs.

Immune response to SARS-CoV-2 variants of concern in vaccinated individuals.

SARS-CoV-2 is evolving with mutations in the receptor binding domain (RBD) being of particular concern. It is important to know how much cross-protection is offered between strains following vaccination or infection. Here, we obtain serum and saliva samples from groups of vaccinated (Pfizer BNT-162b2), infected and uninfected individuals and characterize the antibody response to RBD mutant strains. Vaccinated individuals have a robust humoral response after the second dose and have high IgG antibody titers in the saliva. Antibody responses however show considerable differences in binding to RBD mutants of emerging variants of concern and substantial reduction in RBD binding and neutralization is observed against a patient-isolated South African variant. Taken together our data reinforce the importance of the second dose of Pfizer BNT-162b2 to acquire high levels of neutralizing antibodies and high antibody titers in saliva suggest that vaccinated individuals may have reduced transmission potential. Substantially reduced neutralization for the South African variant further highlights the importance of surveillance strategies to detect new variants and targeting these in future vaccines.