Search

Objectives Antinuclear antibodies (ANA) are important for the diagnosis of various autoimmune diseases. ANA are usually detected by indirect immunofluorescence assay (IFA) using HEp-2 cells (HEp-2 IFA). There are many variables influencing HEp-2 IFA results, such as subjective visual reading, serum screening dilution, substrate manufacturing, microscope components and conjugate. Newer developments on ANA testing that offer novel features adopted by some clinical laboratories include automated computer-assisted diagnosis (CAD) systems and solid phase assays (SPA). Methods A group of experts reviewed current literature and established recommendations on methodological aspects of ANA testing. This process was supported by a two round Delphi exercise. International expert groups that participated in this initiative included (i) the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group “Autoimmunity Testing”; (ii) the European Autoimmune Standardization Initiative (EASI); and (iii) the International Consensus on ANA Patterns (ICAP). Results In total, 35 recommendations/statements related to (i) ANA testing and reporting by HEp-2 IFA; (ii) HEp-2 IFA methodological aspects including substrate/conjugate selection and the application of CAD systems; (iii) quality assurance; (iv) HEp-2 IFA validation/verification approaches and (v) SPA were formulated. Globally, 95% of all submitted scores in the final Delphi round were above 6 (moderately agree, agree or strongly agree) and 85% above 7 (agree and strongly agree), indicating strong international support for the proposed recommendations. Conclusions These recommendations are an important step to achieve high quality ANA testing.

The use of big data in urban mobility research is growing dynamically. However, relatively few studies have been devoted to systematically review the results in this field. Therefore, the aim of the present study is to explore the general characteristics of the application of the big data approach in urban mobility research. For this purpose, the systematic literature review method was applied and the scientific Scopus database was accessed to collect publications relevant to the predefined criteria. Then the papers included in the sample were analysed using quantitative and qualitative techniques, focusing on the trends emerging from the years of publications in the database, the distribution of the papers by journal, the geographical distribution of case-study areas, the methods and data types employed, and their policy implications. This literature review demonstrates the diversity of big datadriven urban mobility research and provides lessons for geography and urban policy in Hungary.

Introduction The latest Position Statement of the American Diabetes Association/European Association for the Study of Diabetes proposes the use of a fixed-ratio combination (FRC) of a long-acting basal insulin and a glucagon-like peptide-1 receptor agonist as part of treatment intensification. This study aimed to assess the effectiveness of the insulin glargine + lixisenatide (iGlarLixi) FRC on glycaemic control and hypoglycaemia in real-life settings. Methods This non-interventional, 26-week study included participants aged 18–80 years with suboptimally controlled type 2 diabetes (T2D) using oral antidiabetics (OADs) ± basal insulin therapy. The primary efficacy endpoint was the proportion of participants who achieved at least a 1% decrease in glycated haemoblobin (HbA1c) level from baseline to week 26. Results Of the 441 participants eligible for entry into the study, 353 were included in the efficacy analyses. These individuals were switched from OADs without (282 [79.9%]) or with (71 [20.1%]) insulin-based treatment. A reduction in HbA1c of at least 1.0% (primary endpoint) was achieved by 215 subjects (60.9%). All glycaemic variables (mean ± standard deviation) improved significantly during follow-up (HbA1c, from 8.9 ± 1.31 to 7.4 ± 0.97%; fasting blood glucose, from 9.0 ± 2.18 to 6.9 ± 1.23 mmol/L; postprandial blood glucose, from 11.3 ± 2.33 to 8.5 ± 1.46 mmol/L; p

The ribosome is a fundamental biomolecular complex that synthesizes proteins in cells. Nascent proteins emerge from the ribosome through a tunnel, where they may interact with the tunnel walls or small molecules such as antibiotics. These interactions can cause translational arrest with notable physiological consequences. Here, we studied the arrest caused by the regulatory peptide VemP, which is known to form α-helices inside the ribosome tunnel near the peptidyl transferase center under specific conditions. We used all-atom molecular dynamics simulations of the entire ribosome and circular dichroism spectroscopy to study the driving forces of helix formation and how VemP causes the translational arrest. To that aim, we compared VemP dynamics in the ribosome tunnel with its dynamics in solution. We show that the VemP peptide has a low helical propensity in water and that the propensity is higher in mixtures of water and trifluorethanol. We propose that helix formation within the ribosome is driven by the interactions of VemP with the tunnel and that a part of VemP acts as an anchor. This anchor might slow down VemP progression through the tunnel enabling α-helix formation, which causes the elongation arrest.

Circular dichroism (CD) spectroscopy is highly sensitive to the secondary structure (SS) composition of proteins. Several methods exist to either estimate the SS composition of a protein or to validate existing structural models using its CD spectrum. The accuracy and precision of these methods depend on the quality of both the measured CD spectrum and the used reference structure. Using a large reference protein set with high-quality CD spectra and synthetic data derived from this set, we quantified deviations from both ideal spectra and reference structures due to experimental limitations. We also determined the impact of these deviations on SS estimation, CD prediction, and SS validation methods of the SESCA analysis package. With regard to the CD spectra, our results suggest intensity scaling errors and non-SS contributions as the main causes of inaccuracies. These factors also can lead to overestimated model errors during validation. The errors of the used reference structures combine non-additively with errors caused by the CD spectrum, which increases the uncertainty of model validation. We have further shown that the effects of scaling errors in the CD spectrum can be nearly eliminated by appropriate re-scaling, and that the accuracy of model validation methods can be improved by accounting for typical non-SS contributions. These improvements have now been implemented within the SESCA package and are available at: https://www.mpibpc.mpg.de/sesca.

Background: Currently no data are available on the real-world effectiveness of the fixed ratio combination of insulin glargine 100 U/ml and lixisenatide (iGlarLixi). This non-interventional study (it was conducted in Hungary) aimed to evaluate its effects on glycaemic control and hypoglycaemia in real-world practice. Methods: The single-arm, 6-month (with follow-up visits at 3 and 6 months) study included uncontrolled adults with type 2 diabetes (HbA1c>7,5%) treated by oral antidiabetics (OAD) +/- basal insulin. iGlarLixi treatment was started at the time of inclusion. Results: Of the included 442 participants, 353 were involved in the efficacy analyses. 282 (79.9%) subjects were treated with OADs, while the remaining 71 (20.1%) with basal insulin and OAD(s) before inclusion. The proportion of participants achieving at least 1.0% HbA1c reduction during the observation period was 60.9% (primary endpoint). All glycaemic variables (mean±SD) improved significantly (p Conclusion: The first prospective, non-interventional study confirmed several results from the LIXILAN programme in a real-life setting. iGlarLixi significantly improved glycaemic control with low frequency of hypoglycaemia and gastrointestinal adverse events in a heterogenous population of people with type 2 diabetes. Results confirm similar efficacy and safety in routine clinical care than in randomized controlled trials. Disclosure J. T. Kis: None. G. Nagy: Employee; Self; Sanofi-Aventis. P. Stella: Employee; Self; Sanofi-Aventis. Funding Sanofi

This book is a very ambitious project, because it covers three decades confused period starting from the very early steps of transformation (crash of Soviet dominance, communist regimes with centra...

A hitel-nemteljesítési csereügyletek (angol rövidítésük CDS, credit default swap) piachálózatának elemzéséről eddig kevés publikáció jelent meg, ezért került elemzésünk fókuszába a CDS termékek piaca. Elemzésünk súlypontja a piaci visszaélések felderítésének újszerű, a hálózatkutatás eszközeit felvonultató alkalmazása a hazai piacra. A kapott eredményeket összevetjük az Európai Értékpapír-piaci Hatóság (ESMA) egy korábban publikált elemzésével, amelyben a kutatók a hálózatelemzés eszközeit a kockázatok és pénzügyi válságok fertőzés útján történő terjedésének feltárásához használták. Az elemzés eredményeit összevetve az európai kutatásokkal az látszik, hogy a magyar vonatkozású CDS piac az európaihoz hasonlóan erős koncentráltságot mutat. Journal of Economic Literature (JEL) kódok: G14, C45

The ribosome is a fundamental biomolecular complex responsible for protein production in cells. Nascent proteins emerge from the ribosome through a tunnel, where they may interact with the tunnel walls or small molecules such as antibiotics. These interactions can cause translational arrest with notable physiologic consequences. Here, we studied the arrest caused by the regulatory peptide VemP, which is known to form an α-helix in the ribosome tunnel near the peptidyl transferase center under specific conditions. We used all-atom molecular dynamics simulations of the entire ribosome and circular dichroism spectroscopy to study the driving forces of helix formation and how VemP causes the translational arrest. To that aim, we compared VemP dynamics in the ribosome tunnel with its dynamics in solution. We show that the VemP sequence has a low helical propensity in water and that the propensity is higher in more hydrophobic solvents. We propose that helix formation within the ribosome is driven by the tunnel environment and that a portion of VemP acts as an anchor. This anchor might slow down VemP progression through the tunnel enabling the α-helix formation, which causes the elongation arrest.

Altered pupillary function may reflect nonconvulsive status epilepticus (NCSE). Neurological pupil index (NPi) assessed by automated pupillometry is a surrogate marker of global pupillary function. We aimed to assess NPi changes in relation to NCSE treatment response. In this prospective observational study, serial automated pupillometry was performed in 68 NCSE episodes. In accordance with local standards, patients were treated with clonazepam (1–2 mg), levetiracetam (40 mg/kg), and lacosamide (5 mg/kg) in a stepwise approach under continuous electroencephalography monitoring until NCSE was terminated. Patients with refractory NCSE received individualized regimens. NPi was assessed bilaterally before and after each treatment step. For statistical analysis, the lower NPi of both sides (minNPi) was used. Nonparametric testing for matched samples and Cohen’s d to estimate effect size were performed. Principal component analysis was applied to assess the contribution of baseline minNPi, age, sex, and NCSE duration to treatment outcome. In 97.1% of 68 episodes, NCSE could be terminated; in 16.2%, NCSE was refractory. In 85.3% of episodes, an abnormal baseline minNPi ≤ 4.0 was obtained. After NCSE termination, minNPi increased significantly (p

Shigella spp. and enterotoxigenic Escherichia coli (ETEC) remain the two leading bacterial causes of diarrheal diseases worldwide. Attempts to develop preventive vaccines against Shigella and ETEC have not yet been successful. The major challenge for a broad Shigella vaccine is the serotype-specific immune response to the otherwise protective LPS O-antigen. ETEC vaccines mainly rely on the heat-labile enterotoxin (LT), while heat-stable toxin (ST) has also been shown to be an important virulence factor. Methods: We constructed a combined Shigella and ETEC vaccine (ShigETEC) based on a live attenuated Shigella strain rendered rough and non-invasive with heterologous expression of two ETEC antigens, LTB and a detoxified version of ST (STN12S). This new vaccine strain was characterized and tested for immunogenicity in relevant animal models. Results: Immunization with ShigETEC resulted in serotype independent protection in the mouse lung shigellosis model and induced high titer IgG and IgA antibodies against bacterial lysates, and anti-ETEC toxin antibodies with neutralizing capacity. Conclusions: ShigETEC is a promising oral vaccine candidate against Shigella and ETEC infections and currently in Phase 1 testing.

• Largest cohort of patients with COVID-19 and neurological symptoms who underwent LP. • In all 30 cases, RT-PCR for SARS-CoV-2 from CSF was negative. • CSF analysis findings, including WBC, were normal in most patients with COVID-19. • Neurological symptoms in COVID-19 seem to be caused mainly by indirect mechanism.

BackgroundThe COVID-19 pandemic is an enormous threat for healthcare systems and economies worldwide that urgently demands effective preventive and therapeutic strategies. Unlike the development of vaccines and new drugs specifically targeting SARS-CoV-2, repurposing of approved or clinically tested drugs can provide an immediate solution.MethodsWe applied a novel computational approach to search among approved and clinically tested drugs from the DrugBank database. Candidates were selected based on Shannon entropy homology and predefined activity profiles of three small molecules with proven anti-SARS-CoV activity and a published data set. Antiviral activity of a predicted drug, azelastine, was tested in vitro in SARS-CoV-2 infection assays with Vero E6 monkey kidney epithelial cells and reconstituted human nasal tissue. The effect on viral replication was assessed by quantification of viral genomes by droplet digital PCR.FindingsThe computational approach with four independent queries identified major drug families, most often and in overlapping fashion anti-infective, anti-inflammatory, anti-hypertensive, anti-histamine and neuroactive drugs. Azelastine, an histamine 1 receptor-blocker, was predicted in multiple screens, and based on its attractive safety profile and availability in nasal formulation, was selected for experimental testing. Azelastine significantly reduced cytopathic effect and SARS-CoV-2 infection of Vero E6 cells with an EC50 of ∼6 μM both in a preventive and treatment setting. Furthermore, azelastine in a commercially available nasal spray tested at 5-fold dilution was highly potent in inhibiting viral propagation in SARS-CoV-2 infected reconstituted human nasal tissue.InterpretationsAzelastine, an anti-histamine, available in nasal sprays developed against allergic rhinitis may be considered as a topical prevention or treatment of nasal colonization with SARS-CoV-2. As such, it could be useful in reducing viral spread and prophylaxis of COVID-19. Ultimately, its potential benefit should be proven in clinical studies.Fundingprovided by the Hungarian government to the National Laboratory of Virology and by CEBINA GmbH.

Circular dichroism (CD) spectroscopy is highly sensitive to the secondary structure (SS) composition of proteins. Several methods exist to either estimate the SS composition of a protein or to validate existing structural models using its CD spectrum. The accuracy and precision of these methods depend on the quality of both the measured CD spectrum and the used reference structure. Using a large reference protein set with high quality CD spectra and synthetic data derived from this set, we quantified deviations from both ideal spectra and reference structures due to experimental limitations. We also determined the impact of these deviations on SS estimation, CD prediction, and SS validation methods of the SESCA analysis package. With regard to the CD spectra, our results suggest intensity scaling errors and non-SS contributions as the main causes of inaccuracies. These factors also can lead to overestimated model errors during validation. The errors of the used reference structures combine non-additively with errors caused by the CD spectrum, which increases the uncertainty of model validation. We have further shown that the effects of scaling errors in the CD spectrum can be nearly eliminated by appropriate re-scaling, and that the accuracy of model validation methods can be improved by accounting for typical non-SS contributions. These improvements have now been implemented within the SESCA package.

Curvularia lunata is an ascomycete filamentous fungus causing local and invasive phaeohyphomycoses in both immunocompromised and immunocompetent patients. Neutrophils are crucial participants of the first line host defense against fungal infections. They migrate to the infected site and eliminate the infectious agents by various mechanisms including phagocytoses, oxidative damage, or formation of neutrophil extracellular trap (NET). Neutropenia may be a risk factor for phaeohyphomycoses, and restoration of the neutrophil function can improve the outcome of the infection. In the present study, interaction of primary human neutrophil granulocytes with the hyphae C. lunata was examined and compared to that with the well characterized filamentous fungal pathogen Aspergillus fumigatus. Neutrophils could recognize the serum opsonized hyphae of C. lunata and attach to them. Myeloperoxidase release was also activated by a soluble factor present in the culture supernatant of the fungus. Induction of the oxidative burst was found to depend on serum opsonization of the hyphae. Although extracellular hydrogen peroxide production was induced, the fungus efficiently blocked the oxidative burst by acidifying the reaction environment. This blockage also affected the NET forming ability of the neutrophils.

During the monitoring of red deer (N = 124) and fallow deer (N = 13) populations in four neighbouring areas, the presence of Fascioloides magna was confirmed in southwestern Hungary. The prevalence and the mean intensity of the infection within the host populations ranged between 0 and 100% and 0-36.3, respectively. The determined prevalences are similar to that observed earlier in other European natural foci. The authors hypothesise that the appearance of F. magna in this region should have been a partly natural- and partly human-influenced process.

Housing markets can be understood as indicators of the spatial pattern of capital investment under contemporary financial capitalism. We take this point of entry in order to analyze core-periphery relations around the turning point of the global financial crisis of 2007–2008 on the Hungarian housing market. The instance of crisis sheds light on patterns of homogenization and differentiation; the effects of which can be understood by exploring housing market activity on various scales from the European to the local/regional. We argue that these two patterns of uneven development are inextricably linked and result in deepening sociospatial polarization.

The anthelmintic resistance of gastrointestinal nematodes is one of the most important, economic risk factors in grazing ruminant systems, all over the world. We have infinitesimal information about the resistance status of nematodes in deer species. Our aim was to determine the presence of BZ resistance in the generalist worm, Haemonchus contortus in pastured sheep and free ranging red and roe deer by RFLP-PCR method based on the detection Phe200Tyr single nucleotide polymorphism. By investigation of 70 worms from each host species, the homozygous susceptible genotype was the most representative in the red deer (100%), the homozygous resistant genotype was most prevalent in the sheep (68.6%) and moderate in the roe deer (17.1%), while the heterozygous genotype was observed in equal proportion in the sheep and roe deer (28.6%). Our results suggest that overlapping habitats of sheep flocks and roe deer could contribute to the occurrence and spread of resistant allele within wildlife.

Background Airway-colonization by Staphylococcus aureus predisposes to the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). Despite extensive antibiotic treatment of intensive care unit patients, limited data are available on the efficacy of antibiotics on bacterial airway colonization and/or prevention of infections. Therefore, microbiologic responses to antibiotic treatment were evaluated in ventilated patients. Methods Results of semiquantitative analyses of S. aureus burden in serial endotracheal-aspirate (ETA) samples and VAT/VAP diagnosis were correlated to antibiotic treatment. Minimum inhibitory concentrations of relevant antibiotics using serially collected isolates were evaluated. Results Forty-eight mechanically ventilated patients who were S. aureus positive by ETA samples and treated with relevant antibiotics for at least 2 consecutive days were included in the study. Vancomycin failed to reduce methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) burden in the airways. Oxacillin was ineffective for MSSA colonization in approximately 30% of the patients, and responders were typically coadministered additional antibiotics. Despite antibiotic exposure, 15 of the 39 patients (approximately 38%) colonized only by S. aureus and treated with appropriate antibiotic for at least 2 days still progressed to VAP. Importantly, no change in antibiotic susceptibility of S. aureus isolates was observed during treatment. Staphylococcus aureus colonization levels inversely correlated with the presence of normal respiratory flora. Conclusions Antibiotic treatment is ineffective in reducing S. aureus colonization in the lower airways and preventing VAT or VAP. Staphylococcus aureus is in competition for colonization with the normal respiratory flora. To improve patient outcomes, alternatives to antibiotics are urgently needed.

Significance The outer membrane of Gram-negative bacteria presents a formidable barrier to the discovery of new antibiotics needed to combat infections by multidrug-resistant bacteria. Targeting essential proteins or processes directly exposed to the environment could bypass this obstacle. Here, we describe a monoclonal antibody that selectively and potently antagonizes BamA, which folds and inserts integral outer membrane β-barrel proteins, by binding to a surface-exposed BamA epitope and, as a result, inhibits bacterial cell growth. Mechanisms of resistance to the antibody reveal that membrane fluidity affects BamA activity. This antibody validates the potential therapeutic strategy of targeting essential, exposed functions and provides a powerful tool for dissecting the fundamental process of folding integral membrane β-barrel proteins in vivo., The folding and insertion of integral β-barrel membrane proteins into the outer membrane of Gram-negative bacteria is required for viability and bacterial pathogenesis. Unfortunately, the lack of selective and potent modulators to dissect β-barrel folding in vivo has hampered our understanding of this fundamental biological process. Here, we characterize a monoclonal antibody that selectively inhibits an essential component of the Escherichia coli β-barrel assembly machine, BamA. In the absence of complement or other immune factors, the unmodified antibody MAB1 demonstrates bactericidal activity against an E. coli strain with truncated LPS. Direct binding of MAB1 to an extracellular BamA epitope inhibits its β-barrel folding activity, induces periplasmic stress, disrupts outer membrane integrity, and kills bacteria. Notably, resistance to MAB1-mediated killing reveals a link between outer membrane fluidity and protein folding by BamA in vivo, underscoring the utility of this antibody for studying β-barrel membrane protein folding within a living cell. Identification of this BamA antagonist highlights the potential for new mechanisms of antibiotics to inhibit Gram-negative bacterial growth by targeting extracellular epitopes.

Circular dichroism spectroscopy is a highly sensitive, but low-resolution technique to study the structure of proteins. Combed with molecular modelling and other complementary techniques, CD spectroscopy can also provide essential information at higher resolution. To this aim, we introduce a new computational method to calculate the electronic circular dichroism spectra of proteins from a three dimensional-model structure or structural ensemble. The method determines the CD spectrum from the average secondary structure composition of the protein using a pre-calculated set of basis spectra. We derived several basis spectrum sets obtained from the experimental CD spectra and secondary structure information of 71 reference proteins and tested the prediction accuracy of these basis spectrum sets through cross-validation. Furthermore, we investigated how prediction accuracy is affected by contributions from amino acid side chain groups and protein flexibility, potential experimental errors of the reference protein spectra, as well as the choice of the secondary structure classification algorithm and the number of basis spectra. We compared the predictive power of our method to previous spectrum prediction algorithms — such as DichroCalc and PDB2CD — and found that SESCA predicts the CD spectra with up to 50% smaller deviation. Our results indicate that SESCA basis sets are robust to experimental error in the reference spectra, and the choice of the secondary structure classification algorithm. For over 80% of the globular reference proteins, SESCA basis sets could accurately predict the experimental spectrum solely from their secondary structure composition. To improve SESCA predictions for the remaining proteins, we applied corrections to account for intensity normalization, contributions from the amino side chains, and conformational flexibility. For globular proteins only intensity scaling improved the prediction accuracy significantly, but our models indicate that side chain contributions and structural flexibility are pivotal for the prediction of shorter peptides and intrinsically disordered proteins.

Umbelopsis ramanniana is an oleaginous fungus belonging to the Mucoromycotina subphylum. Our group had previously detected four double-stranded RNA (dsRNA) bands in the U. ramanniana NRRL 1296 strain by gel electrophoresis. Here we describe the molecular characterization of its dsRNA elements as well as the discovery of four novel dsRNA viruses: Umbelopsis ramanniana virus 1 (UrV1), Umbelopsis ramanniana virus 2 (UrV2), Umbelopsis ramanniana virus 3 (UrV3), and Umbelopsis ramanniana virus 4 (UrV4). Full genomes of UrV1, UrV3, and UrV4 were determined using the full-length amplification of cDNAs (FLAC) technique; they contain two open reading frames (ORF), which putatively encode the coat protein (CP) and the RNA dependent RNA polymerase (RdRp), respectively. In case of UrV2, a partial ORF encoding a partial RdRp gene could be determined. Based on the phylogeny inferred from the RdRp sequences, UrV1 and UrV4 belong to the genus Totivirus, while UrV2 may belong to the genus Victorivirus. UrV3 nested to a novel, unclassified group of Totiviridae, which is related to the genus Totivirus. Hybridization analysis revealed that the dsRNA molecules of UrV1 and UrV4 correspond to the same 5.0-kbp electrophoretic band, whilst the probe for the UrV3 hybridized to the largest, 5.3-kbp and the 3.0-kbp bands of the dsRNA pattern of U. ramanniana. Interestingly, the probe for the UrV2 sequence did not hybridized to any dsRNA bands, but it could be amplified from the isolated 3.0-kbp fragment. By transmission electron microscopy, two different isometric virus particles with about 50 and 35 nm in diameter were detected in U. ramanniana NRRL 1296 indicating that this strain harbor multiple viruses. Beside U. ramanniana, dsRNA elements were also detected in other Umbelopsis isolates with different patterns consisting of 2 to 4 discrete and different sized (0.7–5.3-kbp) dsRNA molecules. Based on a hybridization analysis with UrV1 CP and RdRp probes, the bands with the size of around 5.0-kbp, which were present in all tested Umbelopsis strains, are presumed as possible full mycovirus genomes.

Staphylococcus aureus pneumonia is associated with high mortality irrespective of antibiotic susceptibility. Both MRSA and MSSA strains produce powerful cytotoxins: alpha-hemolysin(Hla) and up to five leukocidins – LukSF-PV, HlgAB, HlgCB, LukED and LukGH (LukAB) – to evade host innate defense mechanisms. Neutralizing cytotoxins has been shown to provide survival benefit in rabbit S. aureus pneumonia models. We studied the mechanisms of protection of ASN100, a combination of two human monoclonal antibodies (mAbs), ASN-1 and ASN-2, that together neutralize Hla and the five leukocidins, in rabbit MRSA and MSSA pneumonia models. Upon prophylactic passive immunization, ASN100 displayed dose-dependent increase in survival and was fully protective against all S. aureus strains tested at 5 or 20 mg/kg doses. Macroscopic and microscopic lung pathology, edema rate, and bacterial burden were evaluated 12 hours post infection and reduced by ASN100. Pharmacokinetic analysis of ASN100 in bronchoalveolar-lavage fluid from uninfected animals detected efficient penetration to lung epithelial lining fluid reaching peak levels between 24 and 48 hours post dosing that were comparable to the mAb concentration measured in serum. These data confirm that the ASN100 mAbs neutralize the powerful cytotoxins of S. aureus in the lung and prevent damage to the mucosal barrier and innate immune cells.

The complement, as part of the innate immune system, represents the first line of defense against Gram-negative bacteria invading the bloodstream. The complement system is a zymogen cascade that ultimately assemble into the so-called membrane attack complex (MAC), which lyses Gram-negative bacteria upon insertion into the outer membrane. Traditionally, serum has been used as complement source, for example to study the bactericidal activity of monoclonal antibodies or antibodies raised upon vaccination. Due to the significant donor to donor variability, as well as susceptibility of complement factors to handling and storage conditions, assay reproducibility using human serum is low. Moreover, the presence of pre-existing antibodies and antimicrobial compounds are confounding factors. To remove antibodies from human serum, we applied κ/λ-light chain specific affinity chromatography, however the method severely reduced the complement activity due to the depletion of complement components. Therefore, we attempted to reconstitute human complement—namely the alternative (rAP) and the classical (rCP) pathways—from purified complement factors. We found that adding C1-inhibitor to the mixture was essential to maintain a stable and functional C1 and thus to generate an active rCP. We further confirmed the functionality of the rCP by testing the complement-dependent bactericidal activity of a human monoclonal antibody, A1124 against an E. coli clinical isolate belonging to the ST131 clonal complex, and that of a polyclonal IVIg against a laboratory E. coli strain (MG1655) not expressing LPS O-antigen and capsule. Although the alternative pathway did not have any bactericidal activity by itself, it enhanced MAC deposition induced by rCP and increased the overall bactericidal activity against the ST131 E. coli strain. In conclusion, we report for the first time the successful in vitro reconstitution of the classical pathway of the human complement to establish a serum-free, complement dependent bactericidal assay. This system offers high level of standardization and could support the study of the complement in different research fields.