β-barrel proteins mediate nutrient uptake in bacteria and serve vital functions in cell signaling and adhesion. For the 14-strand outer membrane protein G of Escherichia coli, opening and closing is ...pH-dependent. Different roles of the extracellular loops in this process were proposed, and X-ray and solution NMR studies were divergent. Here, we report the structure of outer membrane protein G investigated in bilayers of E. coli lipid extracts by magic-angle-spinning NMR. In total, 1847 inter-residue
H-
H and
C-
C distance restraints, 256 torsion angles, but no hydrogen bond restraints are used to calculate the structure. The length of β-strands is found to vary beyond the membrane boundary, with strands 6-8 being the longest and the extracellular loops 3 and 4 well ordered. The site of barrel closure at strands 1 and 14 is more disordered than most remaining strands, with the flexibility decreasing toward loops 3 and 4. Loop 4 presents a well-defined helix.
Dendritic cells express lectins receptors, like DC-SIGN, which allow these cells to sense glycans that are present on various bacterial and viral pathogens. Interaction of DC-SIGN with carbohydrate ...moieties induces maturation of dendritic cells and promotes endocytosis of pathogens which is an important property of these professional antigen presenting cells. Uptake of pathogens by dendritic cells may lead to cross-presentation of antigens or infection of these cells, which ultimately results in activation of virus-specific T cells in draining lymph nodes. Little is known about the interaction of DC-SIGN with influenza A viruses. Here we show that a virus with a non-functional receptor binding site in its hemagglutinin, can replicate in cells expressing DC-SIGN. Also in the absence of sialic acids, which is the receptor for influenza A viruses, these viruses replicate in DC-SIGN expressing cells including human dendritic cells. Furthermore, the efficiency of DC-SIGN mediated infection is dependent on the extent of glycosylation of the viral hemagglutinin.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The performance of the spectral wind wave model SWAN in tidal inlet seas was assessed on the basis of extensive wave measurements conducted in the Amelander Zeegat tidal inlet and the Dutch Eastern ...Wadden Sea, as well as relevant data from other inlets, lakes, estuaries and beaches. We found that the 2006 default SWAN model (version 40.51), the starting point of the investigation, performed reasonably well for measured storm conditions, but three aspects required further attention. First, over the near‐horizontal tidal flats, the computed ratio of integral wave height over water depth showed an apparent upper limit using the default depth‐limited wave breaking formulation and breaker parameter, resulting in an underprediction of wave heights. This problem has been largely solved using a new breaker formulation. The second aspect concerns wave‐current interaction, specifically the wave age effect on waves generated in ambient current, and a proposed enhanced dissipation in negative current gradients. Third, the variance density of lower‐frequency wind waves from the North Sea penetrating through the inlets into the Wadden Sea was underpredicted. This was improved by reducing the bottom friction dissipation relative to that of the default model. After a combined calibration, these improvements have resulted in a relative bias reduction in Hm0 from −3% to −1%, in Tm−1,0 from −7% to −3%, and in Tm01 from −6% to −2%, and consistent reductions in scatter, compared to the 2006 default model.
Key Points
An extensive data set for wave model evaluation was collected in the Wadden Sea
The wave model SWAN generally performs well in tidal inlet seas, with exceptions
Depth‐induced breaking, wave‐current interaction and propagation were improved
A high resolution spectral wave model is used to quantify the spatial wave climate on geographical scales relevant to intra-site variability for marine renewable energy installations. For the first ...time, results are compared to in-situ data from an array of four floating wave buoys, and demonstrate the ability of the spectral wave model SWAN (Simulating WAves Nearshore) to resolve spatial differences in the wave climate. Examination of the model source terms highlights bottom friction and refraction as the primary processes contributing to the observed differences across the site. Wave models for climate assessments for marine renewable energy are not commonly operated at sufficient spatial resolution to accurately resolve intra-site variability. This study demonstrates that high spatial resolution spectral wave models, nested into a larger model domain, have the potential to provide an accurate and detailed prediction of the spatial variability of wave conditions across a marine renewable energy site. As such, they could be implemented to provide a more accurate resource assessment for wave energy array deployments, but also for engineering assessments of other marine energy technologies.
•Unique validation of a high resolution spectral wave model at marine energy site scale.•Short-term differences in Hm0 regularly exceed 10%, and reach 1.3 m during large sea states.•Differences increase at low frequencies, reaching a long term average of 10% for f = 0.05 Hz–0.1 Hz.•SWAN (Simulating WAves Nearshore) wave model accurately predicts spatial differences in a wave field across a wave energy site.•Application of site-scale spectral model improves accuracy of wave data across a site.
Major histocompatibility complex (MHC) class I molecules associate with a variety of peptide ligands during biosynthesis and present these ligands on the cell surface for recognition by cytotoxic T ...cells. We have designed conditional MHC ligands that form stable complexes with MHC molecules but degrade on command, by exposure to a defined photostimulus. 'Empty MHC molecules' generated in this manner can be loaded with arrays of peptide ligands to determine MHC binding properties and to monitor antigen-specific T-cell responses in a high-throughput manner. We document the value of this approach by identifying cytotoxic T-cell epitopes within the H5N1 influenza A/Vietnam/1194/04 genome.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The emergence of novel SARS-CoV-2 variants led to the recommendation of booster vaccinations after Ad26.COV2.S priming. It was previously shown that heterologous booster vaccination induces high ...antibody levels, but how heterologous boosters affect other functional aspects of the immune response remained unknown. Here, we performed immunological profiling of Ad26.COV2.S-primed individuals before and after homologous or heterologous (mRNA-1273 or BNT162b2) booster. Booster vaccinations increased functional antibodies targeting ancestral SARS-CoV-2 and emerging variants. Especially heterologous booster vaccinations induced high levels of functional antibodies. In contrast, T-cell responses were similar in magnitude following homologous or heterologous booster vaccination and retained cross-reactivity towards variants. Booster vaccination led to a minimal expansion of SARS-CoV-2-specific T-cell clones and no increase in the breadth of the T-cell repertoire. In conclusion, we show that Ad26.COV2.S priming vaccination provided a solid immunological base for heterologous boosting, increasing humoral and cellular responses targeting emerging variants of concern.
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•mRNA-based booster after Ad26.COV2.S priming induces strong immune responses•Booster vaccinations induce cross-reactive (non-)neutralizing antibodies•T cells after booster vaccination retain reactivity with novel variants of concern•Booster vaccinations do not increase the T-cell repertoire diversity
Health sciences; Immunology; Immune response; Virology
Infection with influenza B viruses of both the B/Yamagata/16/88-like and the B/Victoria/2/87-like lineage induced hemagglutinin (HA)–specific antibodies with antibody-dependent cellular cytotoxicity ...(ADCC) activity in humans. Only antibodies directed to the HA stalk were capable of mediating ADCC and displayed lineage cross-reactivity.
Abstract
Influenza A virus (IAV) and influenza B virus (IBV) cause substantial morbidity and mortality during annual epidemics. Two distinct lineages of IBV are distinguished, based on variation in hemagglutinin (HA): B/Victoria/2/87-like (B/Vic) and B/Yamagata/16/88-like (B/Yam). Here, we show that, in humans, primary IBV infection with either lineage induces HA-specific antibody-dependent cellular cytotoxicity (ADCC)–mediating antibodies. IBV infection induced antibodies specific to the HA head and stalk, but only HA stalk–specific antibodies mediated ADCC efficiently and displayed cross-reactivity with IBV of both lineages. This corresponds to recent findings that 2 points of contact between the effector and target cell (ie, HA and sialic acid, respectively, and the fragment crystallizable Fc domain and Fcγ receptor IIIα, respectively) are required for efficient ADCC activity and that antibodies specific for the receptor-binding site located in the head domain of HA therefore fail to mediate ADCC. Potentially, ADCC-mediating antibodies directed to the HA stalk of IBV contribute to cross-protective immunity to IBV of both lineages.
Abstract Influenza viruses are responsible for substantial morbidity and mortality during seasonal epidemics. Vaccination is the most effective method to prevent infection, however due to antigenic ...drift of the viral surface protein hemagglutinin (HA), annual influenza virus vaccination is required. In addition to seasonal viruses, certain (avian) influenza A viruses of other subtypes, like H5N1 or H7N9, cause sporadic zoonotic infections. Therefore, the availability of game-changing novel vaccines that induce “universal” immune responses to a wide variety of influenza A virus subtypes is highly desirable. The quest for universal influenza vaccines has fueled the interest in broadly-reactive antibodies specific for the stalk of hemagglutinin (HA) and biological activities of antibodies other than direct virus neutralization, like antibody-dependent cellular cytotoxicity (ADCC). In the present study, we investigated the ADCC response upon influenza virus vaccination and infection in humans using a robust ADCC assay that is based on the use of recombinant HA and a continuous NK cell line that expresses FcγRIII (CD16). This assay offers advantages over existing methods, like ease to perform and possibilities to standardize. We showed that HA-specific ADCC mediating antibodies are induced by vaccination with adjuvanted trivalent seasonal and monovalent H1N1pdm09 inactivated vaccines, and by infection with H1N1pdm09 virus. In addition, the use of chimeric influenza HA with a H1 stem but antigenically irrelevant head domain derived from an avian virus allowed detection of H1-stalk-specific ADCC mediating antibodies. This assay will facilitate the assessment of ADCC mediating serum antibodies after (universal) influenza vaccination or infection and may define ADCC activity as a correlate of (cross-) protection in the future.
High-pathogenicity avian influenza viruses continue to circulate in poultry and wild birds and occasionally infect humans, sometimes with fatal outcomes. Development of vaccines is a priority to ...prepare for potential pandemics but is complicated by antigenic variation of the surface glycoprotein hemagglutinin. We report the immunological profile induced by human immunization with modified vaccinia virus Ankara (MVA) expressing the hemagglutinin gene of influenza A(H5N1) virus A/Vietnam/1194/04 (rMVA-H5).
In a double-blinded phase 1/2a clinical trial, 79 individuals received 1 or 2 injections of rMVA-H5 or vector control. Twenty-seven study subjects received a booster immunization after 1 year. The breadth, magnitude, and properties of vaccine-induced antibody and T-cell responses were characterized.
rMVA-H5 induced broadly reactive antibody responses, demonstrated by protein microarray, hemagglutination inhibition, virus neutralization, and antibody-dependent cellular cytotoxicity assays. Antibodies cross-reacted with antigenically distinct H5 viruses, including the recently emerged subtypes H5N6 and H5N8 and the currently circulating subtype H5N1. In addition, the induction of T cells specific for H5 viruses of 2 different clades was demonstrated.
rMVA-H5 induced immune responses that cross-reacted with H5 viruses of various clades. These findings validate rMVA-H5 as vaccine candidate against antigenically distinct H5 viruses.
NTR3401.
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