Now showing items 1-20 of 3921

    • The diversity and antibacterial activity of culturable actinobacteria isolated from the rhizosphere soil of Deschampsia antarctica (Galindez Island, Maritime Antarctic)

      Tistechok, Stepan; Skvortsova, Maryna; Mytsyk, Yuliia; Fedorenko, Victor; Parnikoza, Ivan; Luzhetskyy, Andriy; Gromyko, Oleksandr; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Springer, 2021-09-01)
      Antarctic actinobacteria, which can be isolated from both soils and marine sediments, demonstrate a wide range of antimicrobial activities as well as significant biosynthetic potential as the producers of biologically active compounds. However, the actinobacterial diversity of the Antarctic region has not yet been sufficiently studied. The present study sought to examine the diversity and antibacterial activity of culturable actinobacteria isolated from the rhizosphere soil of Deschampsia antarctica (É. Desv.), which was collected from Galindez Island, Maritime Antarctic. Among the actinobacteria isolated using a 16S rRNA gene sequence-based phylogenetic analysis process, five genera, namely Streptomyces, Micromonospora, Umezawaea, Kribbella and Micrococcus, were identified. To the best of our knowledge, this is the first report to describe the isolation and initial characterisation of members of the genus Umezawaea from the Antarctic. The isolated actinobacteria were assayed to determine their activity against Gram-positive bacteria, Gram-negative bacteria and yeast. Among the isolated strains, only 30.2% were able to inhibit the growth of at least one of the tested pathogens. The polymerase chain reaction-based screening of the biosynthetic genes revealed the presence of type I polyketide synthases (65.1%), type II polyketide synthases (25.6%) and non-ribosomal peptide synthetases (9.3%) in the actinobacteria strains. The examination of the sensitivity/resistance to antibiotics profile of the actinobacteria strains revealed their high sensitivity in relation to the tested antibiotics. Taken together, the results showed that Antarctic actinobacteria demonstrate potential as the producers of natural bioactive compounds, which means that they represent a valuable prospect for further studies.
    • Total Synthesis of Thuggacin cmc-A and Its Structure Determination.

      Tsutsumi, Tomohiro; Matsumoto, Moe; Iwasaki, Hitomi; Tomisawa, Kei; Komine, Keita; Fukuda, Hayato; Eustache, Jacques; Jansen, Rolf; Hatakeyama, Susumi; Ishihara, Jun; et al. (American Chemical Society, 2021-06-15)
      The first total synthesis of thuggacin cmc-A and the determination of the absolute structure are described. The thuggacin family of antibiotics is of great interest due to the antibiotic activity against Mycobacterium tuberculosis. Based on the assumption that seven stereogenic centers in thuggacin cmc-A would share the same stereochemistry as thuggacin-A, all stereogenic centers of thuggacin cmc-A were strictly constructed in a stereocontrolled manner. The total synthesis allowed its stereostructure to be fully confirmed.
    • Sequential MAVS and MyD88/TRIF signaling triggers anti-viral responses of tick-borne encephalitis virus-infected murine astrocytes.

      Ghita, Luca; Breitkopf, Veronika; Mulenge, Felix; Pavlou, Andreas; Gern, Olivia Luise; Durán, Verónica; Prajeeth, Chittappen Kandiyil; Kohls, Moritz; Jung, Klaus; Stangel, Martin; et al. (Wiley, 2021-07-23)
      Tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is typically transmitted upon tick bite and can cause meningitis and encephalitis in humans. In TBEV-infected mice, mitochondrial antiviral-signaling protein (MAVS), the downstream adaptor of retinoic acid-inducible gene-I (RIG-I)-like receptor (RLR) signaling, is needed to induce early type I interferon (IFN) responses and to confer protection. To characterize the brain-resident cell subset that produces protective IFN-β in TBEV-infected mice, we isolated neurons, astrocytes, and microglia from mice and exposed these cell types to TBEV in vitro. Under such conditions, neurons showed the highest percentage of infected cells, whereas astrocytes and microglia were infected to a lesser extent. In the supernatant (SN) of infected neurons, IFN-β was not detectable, while infected astrocytes showed high and microglia low IFN-β expression. Transcriptome analyses of astrocytes implied that MAVS signaling was needed early after TBEV infection. Accordingly, MAVS-deficient astrocytes showed enhanced TBEV infection and significantly reduced early IFN-β responses. Nevertheless, at later time points, moderate amounts of IFN-β were detected in the SN of infected MAVS-deficient astrocytes. Transcriptome analyses indicated that MAVS deficiency negatively affected the induction of early anti-viral responses, which resulted in significantly increased TBEV replication. Treatment with MyD88 and TRIF inhibiting peptides reduced only late IFN-β responses of TBEV-infected WT astrocytes and blocked entirely IFN-β responses of infected MAVS-deficient astrocytes. Thus, upon TBEV exposure of brain-resident cells, astrocytes are important IFN-β producers showing biphasic IFN-β induction that initially depends on MAVS and later on MyD88/TRIF signaling.
    • Immune responses against SARS-CoV-2 variants after heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination.

      Barros-Martins, Joana; Hammerschmidt, Swantje I; Cossmann, Anne; Odak, Ivan; Stankov, Metodi V; Morillas Ramos, Gema; Dopfer-Jablonka, Alexandra; Heidemann, Annika; Ritter, Christiane; Friedrichsen, Michaela; et al. (Nature, 2021-07-14)
      Currently approved viral vector-based and mRNA-based vaccine approaches against coronavirus disease 2019 (COVID-19) consider only homologous prime-boost vaccination. After reports of thromboembolic events, several European governments recommended using AstraZeneca's ChAdOx1-nCov-19 (ChAd) only in individuals older than 60 years, leaving millions of already ChAd-primed individuals with the decision to receive either a second shot of ChAd or a heterologous boost with mRNA-based vaccines. However, such combinations have not been tested so far. We used Hannover Medical School's COVID-19 Contact Study cohort of healthcare professionals to monitor ChAd-primed immune responses before and 3 weeks after booster with ChAd (n = 32) or BioNTech/Pfizer's BNT162b2 (n = 55). Although both vaccines boosted prime-induced immunity, BNT162b2 induced significantly higher frequencies of spike-specific CD4+ and CD8+ T cells and, in particular, high titers of neutralizing antibodies against the B.1.1.7, B.1.351 and P.1 variants of concern of severe acute respiratory syndrome coronavirus 2.
    • Towards the sustainable discovery and development of new antibiotics.

      Miethke, Marcus; Pieroni, Marco; Weber, Tilmann; Brönstrup, Mark; Hammann, Peter; Halby, Ludovic; Arimondo, Paola B; Glaser, Philippe; Aigle, Bertrand; Bode, Helge B; et al. (Springer Nature, 2021-08-19)
      An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics. We propose both short-term and long-term solutions to overcome the most urgent limitations in the various sectors of research and funding, aiming to bridge the gap between academic, industrial and political stakeholders, and to unite interdisciplinary expertise in order to efficiently fuel the translational pipeline for the benefit of future generations.
    • Therapeutic HNF4A mRNA attenuates liver fibrosis in a preclinical model.

      Yang, Taihua; Poenisch, Marion; Khanal, Rajendra; Hu, Qingluan; Dai, Zhen; Li, Ruomeng; Song, Guangqi; Yuan, Qinggong; Yao, Qunyan; Shen, Xizhong; et al. (Elsevier, 2021-08-25)
      Background & aims: Therapeutic targeting of injuries that require transient restoration of proteins by mRNA delivery is an attractive approach that, until recently, has remained poorly explored. In this study, we examined the therapeutic utility of mRNA delivery for liver fibrosis and cirrhosis. Specifically, we aimed to demonstrate the therapeutic efficacy of human hepatocyte nuclear factor alpha (HNF4A) mRNA in mouse models of fibrosis and cirrhosis. Methods: We investigated restoration of hepatocyte functions by HNF4A mRNA transfection in vitro, and analyzed the attenuation of liver fibrosis and cirrhosis in multiple mouse models, by delivering hepatocyte-targeted biodegradable lipid nanoparticles (LNPs) encapsulating HNF4A mRNA. To identify potential mechanisms of action, we performed microarray-based gene expression profiling, single-cell RNA sequencing, and chromatin immunoprecipitation. We used primary liver cells and human liver buds for additional functional validation. Results: Expression of HNF4A mRNA led to restoration of the metabolic activity of fibrotic primary murine and human hepatocytes in vitro. Repeated in vivo delivery of LNP-encapsulated HNF4A mRNA induced a robust inhibition of fibrogenesis in 4 independent mouse models of hepatotoxin- and cholestasis-induced liver fibrosis. Mechanistically, we discovered that paraoxonase 1 is a direct target of HNF4A and it contributes to HNF4A-mediated attenuation of liver fibrosis via modulation of liver macrophages and hepatic stellate cells. Conclusion: Collectively, our findings provide the first direct preclinical evidence of the applicability of HNF4A mRNA therapeutics for the treatment of fibrosis in the liver. Lay summary: Liver fibrosis and cirrhosis remain unmet medical needs and contribute to high mortality worldwide. Herein, we take advantage of a promising therapeutic approach to treat liver fibrosis and cirrhosis. We demonstrate that restoration of a key gene, HNF4A, via mRNA encapsulated in lipid nanoparticles decreased injury in multiple mouse models of fibrosis and cirrhosis. Our study provides proof-of-concept that mRNA therapy is a promising strategy for reversing liver fibrosis and cirrhosis.
    • Different rates of pollen and seed gene flow cause branch-length and geographic cytonuclear discordance within Asian butternuts.

      Xu, Lin-Lin; Yu, Rui-Min; Lin, Xin-Rui; Zhang, Bo-Wen; Li, Nan; Lin, Kui; Zhang, Da-Yong; Bai, Wei-Ning; CiiM, Zentrum für individualisierte Infektionsmedizin, Feodor-Lynen-Str.7, 30625 Hannover. (Wiley, 2021-07-13)
      opological cytonuclear discordance is commonly observed in plant phylogenetic and phylogeographic studies, yet few studies have attempted to detect two other forms of cytonuclear discordance (branch length and geographical) and to uncover the causes of the discordance. We used the whole nuclear and chloroplast genome data from 80 individual Asian butternuts to reveal the pattern and processes of cytonuclear discordance. Our findings indicate that the chloroplast genome had substantially deeper divergence (branch-length discordance) and a steeper cline in the contact zone (geographic discordance) compared with the nuclear genome. After various hypothesis have been tested, the results suggest that incomplete lineage sorting, positive selection and cytonuclear incompatibility are probably insufficient to explain this pattern. However, isolation-by-distance analysis and gene flow estimation point to a much higher level of gene flow by pollen compared with by seeds, which may have slowed down lineage divergence and mediated wider contact for nuclear genome compared with the chloroplast genome. Altogether, this study highlights a critical role of sex-biased dispersal in causing discordance between the nuclear and plastid genome of Asian butternuts. Given its ubiquity among plants, asymmetric gene flow should be given a high priority in future studies of cytonuclear discordance.
    • Identification of cell lines CL-14, CL-40 and CAL-51 as suitable models for SARS-CoV-2 infection studies.

      Pommerenke, Claudia; Rand, Ulfert; Uphoff, Cord C; Nagel, Stefan; Zaborski, Margarete; Hauer, Vivien; Kaufmann, Maren; Meyer, Corinna; Denkmann, Sabine A; Riese, Peggy; et al. (PLOS, 2021-08-02)
      The SARS-CoV-2 pandemic is a major global threat that sparked global research efforts. Pre-clinical and biochemical SARS-CoV-2 studies firstly rely on cell culture experiments where the importance of choosing an appropriate cell culture model is often underestimated. We here present a bottom-up approach to identify suitable permissive cancer cell lines for drug screening and virus research. Human cancer cell lines were screened for the SARS-CoV-2 cellular entry factors ACE2 and TMPRSS2 based on RNA-seq data of the Cancer Cell Line Encyclopedia (CCLE). However, experimentally testing permissiveness towards SARS-CoV-2 infection, we found limited correlation between receptor expression and permissiveness. This underlines that permissiveness of cells towards viral infection is determined not only by the presence of entry receptors but is defined by the availability of cellular resources, intrinsic immunity, and apoptosis. Aside from established cell culture infection models CACO-2 and CALU-3, three highly permissive human cell lines, colon cancer cell lines CL-14 and CL-40 and the breast cancer cell line CAL-51 and several low permissive cell lines were identified. Cell lines were characterised in more detail offering a broader choice of non-overexpression in vitro infection models to the scientific community. For some cell lines a truncated ACE2 mRNA and missense variants in TMPRSS2 might hint at disturbed host susceptibility towards viral entry.
    • Defective interferon amplification and impaired host responses against influenza virus in obese mice.

      Gaur, Pratibha; Riehn, Mathias; Zha, Lisha; Köster, Mario; Hauser, Hansjörg; Wirth, Dagmar; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Wiley, 2021-07-27)
      Objective: Obesity is a major risk factor that increases morbidity and mortality upon infection. Although type I and type III interferon (IFN)-induced innate immune responses represent the first line of defense against viral infections, their functionality in the context of metabolic disorders remains largely obscure. This study aimed to investigate IFN responses upon respiratory viral infection in obese mice. Methods: The activation of IFNs as well as IFN regulatory factors (IRFs) upon H3N2 influenza infection in mice upon high-fat-diet feeding was investigated. Results: Influenza infection of obese mice was characterized by higher mortalities. In-depth analysis revealed impaired induction of both type I and type III IFNs as well as markedly reduced IFN responses. Notably, it was found that IRF7 gene expression in obese animals was reduced in homeostasis, and its induction by the virus was strongly attenuated. Conclusions: The results suggest that the attenuated IRF7 expression and induction are responsible for the reduced expression levels of type I and III IFNs and, thus, for the higher susceptibility and severity of respiratory infections in obese mice. © 2021 The Authors. Obesity published by Wiley Periodicals LLC on behalf of The Obesity Society (TOS).
    • Assessment of effective mitigation and prediction of the spread of SARS-CoV-2 in Germany using demographic information and spatial resolution.

      Kühn, Martin J; Abele, Daniel; Mitra, Tanmay; Koslow, Wadim; Abedi, Majid; Rack, Kathrin; Siggel, Martin; Khailaie, Sahamoddin; Klitz, Margrit; Binder, Sebastian; et al. (Elsevier, 2021-06-30)
      on-pharmaceutical interventions (NPIs) are important to mitigate the spread of infectious diseases as long as no vaccination or outstanding medical treatments are available. We assess the effectiveness of the sets of non-pharmaceutical interventions that were in place during the course of the Coronavirus disease 2019 (Covid-19) pandemic in Germany. Our results are based on hybrid models, combining SIR-type models on local scales with spatial resolution. In order to account for the age-dependence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we include realistic prepandemic and recently recorded contact patterns between age groups. The implementation of non-pharmaceutical interventions will occur on changed contact patterns, improved isolation, or reduced infectiousness when, e.g., wearing masks. In order to account for spatial heterogeneity, we use a graph approach and we include high-quality information on commuting activities combined with traveling information from social networks. The remaining uncertainty will be accounted for by a large number of randomized simulation runs. Based on the derived factors for the effectiveness of different non-pharmaceutical interventions over the past months, we provide different forecast scenarios for the upcoming time.
    • Expanding the Myxochelin Natural Product Family by Nicotinic Acid Containing Congeners.

      Frank, Nicolas A; Széles, Márió; Akone, Sergi H; Rasheed, Sari; Hüttel, Stephan; Frewert, Simon; Hamed, Mostafa M; Herrmann, Jennifer; Schuler, Sören M M; Hirsch, Anna K H; et al. (MDPI, 2021-08-14)
      Myxobacteria represent a viable source of chemically diverse and biologically active secondary metabolites. The myxochelins are a well-studied family of catecholate-type siderophores produced by various myxobacterial strains. Here, we report the discovery, isolation, and structure elucidation of three new myxochelins N1-N3 from the terrestrial myxobacterium Corallococcus sp. MCy9049, featuring an unusual nicotinic acid moiety. Precursor-directed biosynthesis (PDB) experiments and total synthesis were performed in order to confirm structures, improve access to pure compounds for bioactivity testing, and to devise a biosynthesis proposal. The combined evaluation of metabolome and genome data covering myxobacteria supports the notion that the new myxochelin congeners reported here are in fact frequent side products of the known myxochelin A biosynthetic pathway in myxobacteria.
    • Optimization of Artificial Siderophores as Ga-Complexed PET Tracers for In Vivo Imaging of Bacterial Infections.

      Peukert, Carsten; Langer, Laura N B; Wegener, Sophie M; Tutov, Anna; Bankstahl, Jens P; Karge, Bianka; Bengel, Frank M; Ross, Tobias L; Brönstrup, Mark; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (American Chemical Society (ACS), 2021-08-09)
      The diagnosis of bacterial infections at deep body sites benefits from noninvasive imaging of molecular probes that can be traced by positron emission tomography (PET). We specifically labeled bacteria by targeting their iron transport system with artificial siderophores. The cyclen-based probes contain different binding sites for iron and the PET nuclide gallium-68. A panel of 11 siderophores with different iron coordination numbers and geometries was synthesized in up to 8 steps, and candidates with the best siderophore potential were selected by a growth recovery assay. The probes [68Ga]7 and [68Ga]15 were found to be suitable for PET imaging based on their radiochemical yield, radiochemical purity, and complex stability in vitro and in vivo. Both showed significant uptake in mice infected with Escherichia coli and were able to discern infection from lipopolysaccharide-triggered, sterile inflammation. The study qualifies cyclen-based artificial siderophores as readily accessible scaffolds for the in vivo imaging of bacteria.
    • Recombinant protein production provoked accumulation of ATP, fructose-1,6-bisphosphate and pyruvate in E. coli K12 strain TG1.

      Weber, Jan; Li, Zhaopeng; Rinas, Ursula; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (BMC, 2021-08-26)
      Background: Recently it was shown that production of recombinant proteins in E. coli BL21(DE3) using pET based expression vectors leads to metabolic stress comparable to a carbon overfeeding response. Opposite to original expectations generation of energy as well as catabolic provision of precursor metabolites were excluded as limiting factors for growth and protein production. On the contrary, accumulation of ATP and precursor metabolites revealed their ample formation but insufficient withdrawal as a result of protein production mediated constraints in anabolic pathways. Thus, not limitation but excess of energy and precursor metabolites were identified as being connected to the protein production associated metabolic burden. Results: Here we show that the protein production associated accumulation of energy and catabolic precursor metabolites is not unique to E. coli BL21(DE3) but also occurs in E. coli K12. Most notably, it was demonstrated that the IPTG-induced production of hFGF-2 using a tac-promoter based expression vector in the E. coli K12 strain TG1 was leading to persistent accumulation of key regulatory molecules such as ATP, fructose-1,6-bisphosphate and pyruvate. Conclusions: Excessive energy generation, respectively, accumulation of ATP during recombinant protein production is not unique to the BL21(DE3)/T7 promoter based expression system but also observed in the E. coli K12 strain TG1 using another promoter/vector combination. These findings confirm that energy is not a limiting factor for recombinant protein production. Moreover, the data also show that an accelerated glycolytic pathway flux aggravates the protein production associated "metabolic burden". Under conditions of compromised anabolic capacities cells are not able to reorganize their metabolic enzyme repertoire as required for reduced carbon processing.
    • [The contribution of epidemiological models to the description of the outbreak of the COVID-19 pandemic].

      Priesemann, Viola; Meyer-Hermann, Michael; Pigeot, Iris; Schöbel, Anita; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Springer, 2021-07-30)
      After the global outbreak of the COVID-19 pandemic, an infection dynamic of immense extent developed. Since then, numerous measures have been taken to bring the infection under control. This was very successful in the spring of 2020, while the number of infections rose sharply the following autumn. To predict the occurrence of infections, epidemiological models are used. These are in principle a very valuable tool in pandemic management. However, they still partly need to be based on assumptions regarding the transmission routes and possible drivers of the infection dynamics. Despite numerous individual approaches, systematic epidemiological data are still lacking with which, for example, the effectiveness of individual measures could be quantified. Such information generated in studies is needed to enable reliable predictions regarding the further course of the pandemic. Thereby, the complexity of the models could develop hand in hand with the complexity of the available data. In this article, after delineating two basic classes of models, the contribution of epidemiological models to the assessment of various central aspects of the pandemic, such as the reproduction rate, the number of unreported cases, infection fatality rate, and the consideration of regionality, is shown. Subsequently, the use of the models to quantify the impact of measures and the effects of the "test-trace-isolate" strategy is described. In the concluding discussion, the limitations of such modelling approaches are juxtaposed with their advantages.
    • Helical reconstruction of and needle filaments attached to type 3 basal bodies.

      Kotov, Vadim; Lunelli, Michele; Wald, Jiri; Kolbe, Michael; Marlovits, Thomas C; CSSB, Centre for Structural Systembiologie, Notkestr.85, 22607 Hamburg. Germany. (Elsevier, 2021-06-27)
      Gram-negative pathogens evolved a syringe-like nanomachine, termed type 3 secretion system, to deliver protein effectors into the cytoplasm of host cells. An essential component of this system is a long helical needle filament that protrudes from the bacterial surface and connects the cytoplasms of the bacterium and the eukaryotic cell. Previous structural research was predominantly focused on reconstituted type 3 needle filaments, which lacked the biological context. In this work we introduce a facile procedure to obtain high-resolution cryo-EM structure of needle filaments attached to the basal body of type 3 secretion systems. We validate our approach by solving the structure of Salmonella PrgI filament and demonstrate its utility by obtaining the first high-resolution cryo-EM reconstruction of Shigella MxiH filament. Our work paves the way to systematic structural characterization of attached type 3 needle filaments in the context of mutagenesis studies, protein structural evolution and drug development.
    • Comparison of Chicken Cecal Microbiota after Metaphylactic Treatment or Following Administration of Feed Additives in a Broiler Farm with Enterococcal Spondylitis History.

      Hankel, Julia; Bodmann, Björn; Todte, Matthias; Galvez, Eric; Strowig, Till; Radko, Dimitri; Antakli, Ali; Visscher, Christian; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-08-23)
      Minimizing the clinical signs of Enterococcus cecorum infections causing enterococcal spondylitis in broiler herds is successful when initiated as metaphylaxis in the first week of life. Mechanistically, either the Enterococcus species present at that time are reduced by antibiotic treatment or antibiotic treatment might induce changes in intestinal microbiota composition with an indirect and subsequent influence. The aim of the present study was to examine the cecal microbiota of chickens after administering lincospectin or different additives to evaluate whether these additives have lincospectin-like effects on microbiota. Therefore, 157,400 broiler chickens were reared in four chicken houses (~40,000 birds each) on a broiler farm with history of enterococcal spondylitis. Each flock was treated either with lincospectin or water soluble esterified butyrins, Bacillus (B.) licheniformis or palm oil was added via drinking water during the first days of life. Ten birds per house were dissected at days 11, 20 and 33 of life and cecal microbiota were analyzed (16S rRNA gene sequencing). Lincospectin treatment elicited significant changes in the cecal microbiota composition until slaughter age. Among the tested additives, effects of B. licheniformis on cecal microbiota composition were most similar to those seen after the treatment with lincospectin at day 11.
    • Fate mapping of single NK cells identifies a type 1 innate lymphoid-like lineage that bridges innate and adaptive recognition of viral infection.

      Flommersfeld, Sophie; Böttcher, Jan P; Ersching, Jonatan; Flossdorf, Michael; Meiser, Philippa; Pachmayr, Ludwig O; Leube, Justin; Hensel, Inge; Jarosch, Sebastian; Zhang, Qin; et al. (Cell Press, 2021-08-20)
      Upon viral infection, natural killer (NK) cells expressing certain germline-encoded receptors are selected, expanded, and maintained in an adaptive-like manner. Currently, these are thought to differentiate along a common pathway. However, by fate mapping of single NK cells upon murine cytomegalovirus (MCMV) infection, we identified two distinct NK cell lineages that contributed to adaptive-like responses. One was equivalent to conventional NK (cNK) cells while the other was transcriptionally similar to type 1 innate lymphoid cells (ILC1s). ILC1-like NK cells showed splenic residency and strong cytokine production but also recognized and killed MCMV-infected cells, guided by activating receptor Ly49H. Moreover, they induced clustering of conventional type 1 dendritic cells and facilitated antigen-specific T cell priming early during MCMV infection, which depended on Ly49H and the NK cell-intrinsic expression of transcription factor Batf3. Thereby, ILC1-like NK cells bridge innate and adaptive viral recognition and unite critical features of cNK cells and ILC1s.
    • Secondary metabolite biosynthetic diversity in the fungal family Hypoxylaceae and Xylaria hypoxylon.

      Kuhnert, E; Navarro-Muñoz, J C; Becker, K; Stadler, M; Collemare, J; Cox, R J; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2021-08-26)
      To date little is known about the genetic background that drives the production and diversification of secondary metabolites in the Hypoxylaceae. With the recent availability of high-quality genome sequences for 13 representative species and one relative (Xylaria hypoxylon) we attempted to survey the diversity of biosynthetic pathways in these organisms to investigate their true potential as secondary metabolite producers. Manual search strategies based on the accumulated knowledge on biosynthesis in fungi enabled us to identify 783 biosynthetic pathways across 14 studied species, the majority of which were arranged in biosynthetic gene clusters (BGC). The similarity of BGCs was analysed with the BiG-SCAPE engine which organised the BGCs into 375 gene cluster families (GCF). Only ten GCFs were conserved across all of these fungi indicating that speciation is accompanied by changes in secondary metabolism. From the known compounds produced by the family members some can be directly correlated with identified BGCs which is highlighted herein by the azaphilone, dihydroxynaphthalene, tropolone, cytochalasan, terrequinone, terphenyl and brasilane pathways giving insights into the evolution and diversification of those compound classes. Vice versa, products of various BGCs can be predicted through homology analysis with known pathways from other fungi as shown for the identified ergot alkaloid, trigazaphilone, curvupallide, viridicatumtoxin and swainsonine BGCs. However, the majority of BGCs had no obvious links to known products from the Hypoxylaceae or other well-studied biosynthetic pathways from fungi. These findings highlight that the number of known compounds strongly underrepresents the biosynthetic potential in these fungi and that a tremendous number of unidentified secondary metabolites is still hidden. Moreover, with increasing numbers of genomes for further Hypoxylaceae species becoming available, the likelihood of revealing new biosynthetic pathways that encode new, potentially useful compounds will significantly improve. Reaching a better understanding of the biology of these producers, and further development of genetic methods for their manipulation, will be crucial to access their treasures.
    • Impaired immune response mediated by prostaglandin E2 promotes severe COVID-19 disease.

      Ricke-Hoch, Melanie; Stelling, Elisabeth; Lasswitz, Lisa; Gunesch, Antonia P; Kasten, Martina; Zapatero-Belinchón, Francisco J; Brogden, Graham; Gerold, Gisa; Pietschmann, Thomas; Montiel, Virginie; et al. (PLOS, 2021-08-04)
      he SARS-CoV-2 coronavirus has led to a pandemic with millions of people affected. The present study finds that risk-factors for severe COVID-19 disease courses, i.e. male sex, older age and sedentary life style are associated with higher prostaglandin E2 (PGE2) serum levels in blood samples from unaffected subjects. In COVID-19 patients, PGE2 blood levels are markedly elevated and correlate positively with disease severity. SARS-CoV-2 induces PGE2 generation and secretion in infected lung epithelial cells by upregulating cyclo-oxygenase (COX)-2 and reducing the PG-degrading enzyme 15-hydroxyprostaglandin-dehydrogenase. Also living human precision cut lung slices (PCLS) infected with SARS-CoV-2 display upregulated COX-2. Regular exercise in aged individuals lowers PGE2 serum levels, which leads to increased Paired-Box-Protein-Pax-5 (PAX5) expression, a master regulator of B-cell survival, proliferation and differentiation also towards long lived memory B-cells, in human pre-B-cell lines. Moreover, PGE2 levels in serum of COVID-19 patients lowers the expression of PAX5 in human pre-B-cell lines. The PGE2 inhibitor Taxifolin reduces SARS-CoV-2-induced PGE2 production. In conclusion, SARS-CoV-2, male sex, old age, and sedentary life style increase PGE2 levels, which may reduce the early anti-viral defense as well as the development of immunity promoting severe disease courses and multiple infections. Regular exercise and Taxifolin treatment may reduce these risks and prevent severe disease courses.
    • Concatemeric Broccoli reduces mRNA stability and induces aggregates.

      Rink, Marco R; Baptista, Marisa A P; Flomm, Felix J; Hennig, Thomas; Whisnant, Adam W; Wolf, Natalia; Seibel, Jürgen; Dölken, Lars; Bosse, Jens B; HIRI, Helmholtz-Institut für RNA-basierte Infektionsforschung, Josef-Shneider Strasse 2, 97080 Würzburg, Germany. (PLOS, 2021-08-04)
      Fluorogenic aptamers are an alternative to established methodology for real-time imaging of RNA transport and dynamics. We developed Broccoli-aptamer concatemers ranging from 4 to 128 substrate-binding site repeats and characterized their behavior fused to an mCherry-coding mRNA in transient transfection, stable expression, and in recombinant cytomegalovirus infection. Concatemerization of substrate-binding sites increased Broccoli fluorescence up to a concatemer length of 16 copies, upon which fluorescence did not increase and mCherry signals declined. This was due to the combined effects of RNA aptamer aggregation and reduced RNA stability. Unfortunately, both cellular and cytomegalovirus genomes were unable to maintain and express high Broccoli concatemer copy numbers, possibly due to recombination events. Interestingly, negative effects of Broccoli concatemers could be partially rescued by introducing linker sequences in between Broccoli repeats warranting further studies. Finally, we show that even though substrate-bound Broccoli is easily photobleached, it can still be utilized in live-cell imaging by adapting a time-lapse imaging protocol.