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Joining by forming is a commonly applied technique in the automotive industry to assemble parts of thin metal sheets to meet the demands of lightweight design. The joining operation induces changes in material behaviour due to cold forming, that can be observed in increased hardness in the area close to the joint neck compared to the base material. Complex geometrical features of clinched joints on a small scale and the lack of non-destructive methods to track local stresses and strains require a combined approach utilizing numerical and experimental techniques. Numerical process and loading simulation are performed utilizing commercial finite element software LS-Dyna®. Hardness measurements in the joint are carried out to assess the impact of forming operation. Cyclic material properties are derived from Vickers hardness to estimate fatigue life with the Local Strain Approach using the damage parameter PSWT. Fatigue life estimation with failure criterion crack initiation obtained from simulation results is compared to those from experiments. The results obtained indicate that the Local Strain Approach is suitable for fatigue life estimations of clinched joints under constant amplitude loading as long as the influence of the forming process is considered.

In 2018 the German Research Association of Mechanical Engineering (FKM) will present a new guideline for calculating the fatigue crack initiation life of structures and components . The user of this guideline … is able to calculate the fatigue life for crack initiation for structures of steel, cast steel and aluminium alloy … has to perform an elastic FE-calculation and gets the quality of an elastic-plastic calculation … is able to determine the cyclic material parameters and the damage parameter Wöhler curve by the ultimate tensile strength Rm … is able to calculate the fatigue life in HCF and LCF for constant and variable amplitude loading This paper presents the algorithms of the new guideline, gives an overview about the mechanical background and discusses the results for specimens of steel and aluminium alloys. It also shows results comparing the new to the current FKM guideline for a given steel structure.

During the first wave of the pandemic, we compared the occurrence of subjectively experienced COVID‐19‐like symptoms and true severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) seroconversion rates among medical personnel in general practices. This cross‐sectional study determined the SARS‐CoV‐2‐specific immunoglobulin G (IgG) antibody status of medical staff from 100 outpatient practices in Germany. Study cohort characteristics and COVID‐19‐like symptoms were obtained by questionnaires. The initial screening for SARS‐CoV‐2‐recognizing antibodies was performed using a commercial chemiluminescence microparticle immunoassay. Positive results were controlled with another approved test. Samples with discrepant results were subjected to a third IgG‐binding assay and a neutralization test. A total of 861 participants were included, 1.7% (n = 15) of whom tested positive for SARS‐CoV‐specific IgG in the initial screening test. In 46.6% (n = 7) of positive cases, test results were confirmed by an independent test. In the eight samples with discrepant results, neither spike‐specific antibodies nor in vitro neutralizing capacity were detectable, resulting in a genuine seroprevalence rate of 0.8%. 794 participants completed the questionnaire. Intriguingly, a total of 53.7% (n = 426) of them stated episodes of COVID‐19‐like symptoms. Except for smell and taste dysfunction, there were no significant differences between the groups with and without laboratory‐confirmed SARS‐CoV‐2 seroconversion. Our results demonstrated that only 0.8% of participants acquired SARS‐CoV‐2 even though 53.7% of participants reportedly experienced COVID‐19‐like symptoms. Thus, even among medical staff, self‐diagnosis based on subjectively experienced symptoms does not have a relevant predictive value. [ABSTRACT FROM AUTHOR]

Data about the diagnostic efficiency of bilateral bronchoalveolar lavage (BAL) samples and endotracheal aspirates (EA) testing for common viral respiratory infections are scarce. We analyzed data from 167 cases, where bilateral BAL samples were tested, and from 101 cases, where BAL samples and EA were tested. Multiplex polymerase chain reaction (PCR) was performed with the fast track diagnostics viral respiratory panel, producing data on the adenovirus, coronavirus, enterovirus, human metapneumovirus, bocavirus, influenza virus, parainfluenza virus, rhinovirus, and respiratory syncytial virus status of patients with respiratory disease symptoms. In the bilateral BAL cohort, 46 (27.5%) cases were positive for at least one of the viruses mentioned above in both samples. Discrepant results (virus not detected on one side) were seen in six (3.6%) cases. In the BAL versus EA cohort, 12 (11.9%) cases were positive in both materials, discrepant results (only one material being positive) were observed in 11 (10.9%) cases, with seven (63.6%) BAL samples, and four (36.4%) EA being positive. Bilateral sampling does not significantly improve the diagnostic efficiency of BAL for the detection of common respiratory viral pathogens via PCR. The diagnostic quality of EA and BAL samples for the detection of common viral respiratory pathogens is comparable. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the LIAISON® SARS-CoV-2 antigen assay (DiaSorin), comparing its performance to real-time polymerase chain reaction (RT-PCR) for the detection of SARS-CoV-2 RNA. 182 (110 PCR-positive and 72 PCR-negative) nasopharyngeal swab samples were taken for the detection of SARS-CoV-2. RT-PCR and antigen assay were performed using the same material. The sensitivity and specificity of the antigen assay were calculated for different cut-offs, with RT-PCR serving as the reference method. Stored clinical samples that were positive for other respiratory viruses were tested to evaluate cross-reactivity. One third (33/110, 30%) were falsely classified as negative, while no false positives were found using the 200 TCID50/mL cut-off for the SARS-CoV-2 antigen as proposed by the manufacturer. This corresponded to a sensitivity of 70% (60–78%) and a specificity of 100% (94–100%). Lowering the cut-off for positivity of the antigen assay to 22.79 or 57.68 TCID50/mL increased the sensitivity of the method, reaching a sensitivity of 92% (85–96%) vs. 79% (70–86%) and a specificity of 81% (69–89%) vs. 99% (91–100%), respectively. The antigen assay reliably detected samples with high SARS-CoV-2 viral loads (≥106 copies SARS-CoV-2/mL), while it cannot differentiate between negative and low positive samples. Cross-reactivity toward other respiratory viruses was not detected. [ABSTRACT FROM AUTHOR]

Virus-specific CD8 T cell response seems to play a significant role in the outcome of hepatitis delta virus (HDV) infection. However, the HDV-specific T cell epitope repertoire and mechanisms of CD8 T cell failure in HDV infection have been poorly characterized. We therefore aimed to characterize HDV-specific CD8 T cell epitopes and the impacts of viral mutations on immune escape. In this study, we predicted peptide epitopes binding the most frequent human leukocyte antigen (HLA) types and assessed their HLA binding capacities. These epitopes were characterized in HDV-infected patients by intracellular gamma interferon (IFN-γ) staining. Sequence analysis of large hepatitis delta antigen (L-HDAg) and HLA typing were performed in 104 patients. The impacts of substitutions within epitopes on the CD8 T cell response were evaluated experimentally and by in silico studies. We identified two HLA-B*27-restricted CD8 T cell epitopes within L-HDAg. These novel epitopes are located in a relatively conserved region of L-HDAg. However, we detected molecular footprints within the epitopes in HLA-B*27-positive patients with chronic HDV infections. The variant peptides were not cross-recognized in HLA-B*27-positive patients with resolved HDV infections, indicating that the substitutions represent viral escape mutations. Molecular modeling of HLA-B*27 complexes with the L-HDAg epitope and its potential viral escape mutations indicated that the structural and electrostatic properties of the bound peptides differ considerably at the T cell receptor interface, which provides a possible molecular explanation for the escape mechanism. This viral escape from the HLA-B*27-restricted CD8 T cell response correlates with a chronic outcome of hepatitis D infection. T cell failure resulting from immune escape may contribute to the high chronicity rate in HDV infection. IMPORTANCE Hepatitis delta virus (HDV) causes severe chronic hepatitis, which affects 20 million people worldwide. Only a small number of patients are able to clear the virus, possibly mediated by a virus-specific T cell response. Here, we performed a systematic screen to define CD8 epitopes and investigated the role of CD8 T cells in the outcome of hepatitis delta and how they fail to eliminate HDV. Overall the number of epitopes identified was very low compared to other hepatotropic viruses. We identified, two HLA-B*27-restricted epitopes in patients with resolved infections. In HLA-B*27-positive patients with chronic HDV infections, however, we detected escape mutations within these identified epitopes that could lead to viral evasion of immune responses. These findings support evidence showing that HLA-B*27 is important for virus-specific CD8 T cell responses, similar to other viral infections. These results have implications for the clinical prognosis of HDV infection and for vaccine development. [ABSTRACT FROM AUTHOR]

Neutralizing antibodies (nAbs) prevent the entry of viruses into permissive cells. Since nAbs represent correlates of protection against the Rabies lyssavirus, the presence of sufficient nAbs indicates effective vaccination. Accordingly, Rabies lyssavirus-specific nAb titers need to be determined in routine diagnostics to identify individuals being at risk of Rabies lyssavirus infections due to insufficient immunity. The current gold standard for the quantification of Rabies lyssavirus-specific nAbs is the rapid fluorescent focus inhibition test (RFFIT). However, RFFITs are expensive and labor-intensive since multiple microplate wells must be evaluated one-by-one by trained personnel through microscopic inspection, which limits the number of samples that can be processed. To overcome this disadvantage, we established a novel assay for Rabies lyssavirus-specific nAbs relying on an in-cell-ELISA (icELISA)-based neutralization test (icNT). The icNT differs from the RFFIT in the readout phase, and can be automatically quantified in minutes using broadly available microplate readers. During the establishment, icNT parameters such as antibody concentrations, permeabilization procedures, blocking reagents, infectious doses, and the duration of infection were optimized. Afterwards, a dose-dependent detection of Rabies lyssavirus neutralization was demonstrated using the WHO Standard Rabies Immunoglobulin reference. A panel of 200 sera with known RFFIT titers revealed very good sensitivity and specificity of the icNT. Furthermore, the icNT showed very good intra- and inter-assay precision. By recognizing Rabies lyssavirus-specific antigens, the assay can be applied immediately to automatically quantify the concentration of Rabies lyssavirus nAbs in routine diagnostics or for various basic research questions such as screening for antiviral compounds., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Because of the shortage of available organs for renal transplantation, strategies enabling the safe use of organs from donors with potential chronic infections such as hepatitis C are necessary. The aim of this study was to analyze the outcome of renal transplant donation from hepatitis C virus (HCV)-positive donors., Methods: Between September 2002 and May 2007, 51 kidneys (34 donors) reactive for HCV antibodies were further evaluated. Six kidneys (5 donors) were transplanted to 6 recipients with known chronic HCV infection. The remaining 29 donors underwent extended virological testing. Nine donors were HCV RNA positive and thus not suitable for HCV-negative patients. Twenty donors (21 kidneys) did not have detectable HCV RNA copies and were transplanted into 21 HCV-negative recipients. Clinical outcomes focusing on safety, allograft function, and de novo HCV infection in the recipient were collected., Results: There were no de novo HCV infections detected in recipients who were HCV negative before transplantation. The extended virological donor screening did not have an impact on median cold ischemia time. Five-year graft survival was 75%., Discussion: Organs from anti-HCV-reactive, nonviremic donors can be transplanted safely to HCV-negative recipients.