RNA vaccines are efficient preventive measures to combat the SARS-CoV-2 pandemic. High levels of neutralizing SARS-CoV-2-antibodies are an important component of vaccine-induced immunity. Shortly after the initial two mRNA vaccine doses, the IgG response mainly consists of the pro-inflammatory subclasses IgG1 and IgG3. Here, we report that several months after the second vaccination, SARS-CoV-2-specific antibodies were increasingly composed of non-inflammatory IgG4, which were further boosted by a third mRNA vaccination and/or SARS-CoV-2 variant breakthrough infections. IgG4 antibodies among all spike-specific IgG antibodies rose on average from 0.04% shortly after the second vaccination to 19.27% late after the third vaccination. This induction of IgG4 antibodies was not observed after homologous or heterologous SARS-CoV-2 vaccination with adenoviral vectors. Single-cell sequencing and flow cytometry revealed substantial frequencies of IgG4-switched B cells within the spike-binding memory B-cell population (median 14.4%; interquartile range (IQR) 6.7–18.1%) compared to the overall memory B-cell repertoire (median 1.3%; IQR 0.9–2.2%) after three immunizations. Importantly, this class switch was associated with a reduced capacity of the spike-specific antibodies to mediate antibody-dependent cellular phagocytosis and complement deposition. Since Fc-mediated effector functions are critical for antiviral immunity, these findings may have consequences for the choice and timing of vaccination regimens using mRNA vaccines, including future booster immunizations against SARS-CoV-2.

Hepatitis C virus (HCV) infection is a major cause of liver disease characterized by inflammation, cell damage, and fibrotic reactions of hepatocytes. Apoptosis has been implicated in the pathogenesis, although it is unclear whether proteases of the caspase family as the central executioners of apoptosis are involved and how caspase activation contributes to liver injury. In the present study, we measured the activation of effector caspases in liver biopsy specimens of patients with chronic HCV infection. The activation of caspase-3, caspase-7, and cleavage of poly(ADP-ribose)polymerase (PARP), a specific caspase substrate, were measured by immunohistochemistry and Western blot analysis by using antibodies that selectively detect the active truncated, but not the inactive precursor forms of the caspases and PARP. We found that caspase activation was considerably elevated in liver lobules of HCV patients in comparison to normal controls. Interestingly, the immunoreactive cells did yet not reveal an overt apoptotic morphology. The extent of caspase activation correlated significantly with the disease grade, i.e., necroinflammatory activity. In contrast, no correlation was observed with other surrogate markers such as serum transaminases and viral load. In biopsy specimens with low activity ( Hepatitis C virus (HCV) infection is one of the major causes of liver disease with an increased risk of cirrhosis and hepatocellular carcinoma. The infection has a high propensity to chronicity, and the majority of HCV carriers have histologic evidence for liver inflammation, cell damage, and fibrotic reactions of hepatocytes. The mechanisms responsible for HCVmediated liver cell damage are poorly understood, and both immune-mediated reactions and direct cytopathic effects of HCV may be involved in its pathogenesis. It has been suggested that apoptosis plays an important role in HCV-associated liver injury, 1-4 although it is unclear which cellular and molecular mechanisms participate in the process.One of the best-defined apoptotic pathways is mediated by the death receptor CD95, a member of the tumor necrosis factor superfamily that is constitutively expressed on hepatocytes. 5 Experiments in mice have shown that agonistic CD95 antibodies cause massive liver cell lysis, resulting in increased serum levels of transaminases and death from fulminant hepatic failure. 6 In patients with chronic HCV infection, expression of CD95 is increased and associated with disease activity and the severity of liver inflammation. 7,8 When HCV-specific T cells migrate towards hepatocytes and recognize viral antigens through the T-cell receptor, they become activated and inducibly express the ligand CD95L that can transduce the apoptotic death signal to CD95-bearing hepatocytes. 2 In addition to CD95L and other cytokines, both structural and nonstructural HCV proteins have been shown to modulate the sensitivity of hepatocytes for cell death. [9][10][11][12][13] Cells undergoing apoptosis show a sequence of morphologic features including membrane...

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f Since the mid-1990s, a steady increase in the occurrence of itraconazole-resistant Aspergillus fumigatus isolates has been observed in clinical contexts, leading to therapeutic failure in the treatment of aspergillosis. This increase has been predominantly linked to a single allele of the cyp51A gene, termed TR/L98H, which is thought to have arisen through the use of agricultural azoles. Here, we investigated the current epidemiology of triazole-resistant A. fumigatus and underlying cyp51A mutations in clinical samples in Germany. From a total of 527 samples, 17 (3.2%) showed elevated MIC 0 values (the lowest concentrations with no visible growth) for at least one of the three substances (itraconazole, voriconazole, and posaconazole) tested. The highest prevalence of resistant isolates was observed in cystic fibrosis patients (5.2%). Among resistant isolates, the TR/L98H mutation in cyp51A was the most prevalent, but isolates with the G54W and M220I substitutions and the novel F219C substitution were also found. The isolate with the G54W substitution was highly resistant to both itraconazole and posaconazole, while all others showed high-level resistance only to itraconazole. For the remaining six isolates, no mutations in cyp51A were found, indicating the presence of other mechanisms. With the exception of the strains carrying the F219C and M220I substitutions, many itraconazole-resistant strains also showed cross-resistance to voriconazole and posaconazole with moderately increased MIC 0 values. In conclusion, the prevalence of azole-resistant A. fumigatus in our clinical test set is lower than that previously reported for other countries. Although the TR/L98H mutation frequently occurs among triazole-resistant strains in Germany, it is not the only resistance mechanism present.