• Intranasal vaccination with an adjuvanted polyphosphazenes nanoparticle-based vaccine formulation stimulates protective immune responses in mice.

      Schulze, Kai; Ebensen, Thomas; Babiuk, Lorne A; Gerdts, Volker; Guzman, Carlos A.; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017-06-01)
      The most promising strategy to sustainably prevent infectious diseases is vaccination. However, emerging as well as re-emerging diseases still constitute a considerable threat. Furthermore, lack of compliance and logistic constrains often result in the failure of vaccination campaigns. To overcome these hurdles, novel vaccination strategies need to be developed, which fulfill maximal safety requirements, show maximal efficiency and are easy to administer. Mucosal vaccines constitute promising non-invasive approaches able to match these demands. Here we demonstrate that nanoparticle (polyphosphazenes)-based vaccine formulations including c-di-AMP as adjuvant, cationic innate defense regulator peptides (IDR) and ovalbumin (OVA) as model antigen were able to stimulate strong humoral and cellular immune responses, which conferred protection against the OVA expressing influenza strain A/WSN/OVAI (H1N1). The presented results confirm the potency of nanoparticle-based vaccine formulations to deliver antigens across the mucosal barrier, but also demonstrate the necessity to include adjuvants to stimulate efficient antigen-specific immune responses.
    • Intranasal vaccination with recombinant outer membrane protein CD and adamantylamide dipeptide as the mucosal adjuvant enhances pulmonary clearance of Moraxella catarrhalis in an experimental murine model.

      Becker, Pablo D; Bertot, Gustavo M; Souss, David; Ebensen, Thomas; Guzmán, Carlos A; Grinstein, Saúl; Virology Laboratory, Ricardo Gutiérrez Children's Hospital, Gallo 1330, 1425 Buenos Aires, Argentina. (2007-04)
      Moraxella catarrhalis causes acute otitis media in children and lower respiratory tract infections in adults and elderly. In children the presence of antibodies against the highly conserved outer membrane protein CD correlates with protection against infection, suggesting that this protein may be useful as a vaccine antigen. However, native CD is difficult to purify, and it is still unclear if recombinant CD (rCD) is a valid alternative. We performed a side-by-side comparison of the immunogenicities and efficacies of vaccine formulations containing native CD and rCD with adamantylamide dipeptide as the mucosal adjuvant. Intranasal vaccination of mice stimulated the production of high CD-specific antibody titers in sera and of secretory immunoglobulin A in mucosal lavages, which cross-recognized both antigens. While vaccination with native CD increased the number of interleukin-2 (IL-2)- and gamma interferon-producing cells, rCD mainly stimulated IL-4-secreting cells. Nevertheless, efficient bacterial clearance was observed in the lungs of challenged mice receiving native CD and in the lungs of challenged mice receiving rCD (96% and 99%, respectively). Thus, rCD is a promising candidate for incorporation in vaccine formulations for use against M. catarrhalis.
    • Invariant NKT Cell-Mediated Modulation of ILC1s as a Tool for Mucosal Immune Intervention.

      Trittel, Stephanie; Vashist, Neha; Ebensen, Thomas; Chambers, Benedict J; Guzmán, Carlos A; Riese, Peggy; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2019-01-01)
      Non-NK group 1 innate lymphoid cells (ILC1s), mainly investigated in the mucosal areas of the intestine, are well-known to contribute to anti-parasitic and anti-bacterial immune responses. Recently, our group revealed that lung ILC1s become activated during murine influenza infection, thereby contributing to viral clearance. In this context, worldwide seasonal influenza infections often result in severe disease outbreaks leading to high morbidity and mortality. Therefore, new immune interventions are urgently needed. In contrast to NK cells, the potential of non-NK ILC1s to become functionally tailored by immune modulators to contribute to the combat against mucosal-transmitted viral pathogens has not yet been addressed. The present study aimed at assessing the potential of ILC1s to become modulated by iNKT cells activated through the CD1d agonist αGalCerMPEG. Our results demonstrate an improved functional responsiveness of murine lung and splenic ILC1s following iNKT cell stimulation by the mucosal route, as demonstrated by enhanced surface expression of TNF-related apoptosis-inducing ligand (TRAIL), CD49a and CD28, and increased secretion of IFNγ. Interestingly, iNKT cell stimulation also induced the expression of the immune checkpoint molecules GITR and CTLA-4, which represent crucial points of action for immune regulation. An in vivo influenza infection model revealed that intranasal activation of ILC1s by αGalCerMPEG contributed to increased viral clearance as shown by reduced viral loads in the lungs. The findings that ILC1s can become modulated by mucosally activated iNKT cells in a beneficial manner emphasize their up to now underestimated potential and renders them to be considered as targets for novel immune interventions.
    • Invasion and intracellular survival of Bordetella bronchiseptica in mouse dendritic cells.

      Guzman, C A; Rohde, Manfred; Bock, M; Timmis, K N (1994-12)
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    • Isolation of Novel Ultramicrobacteria Classified as Actinobacteria from Five Freshwater Habitats in Europe and Asia

      Hahn, Martin W.; Lünsdorf, Heinrich; Wu, Qinglong; Schauer, Michael; Höfle, Manfred G.; Boenigk, Jens; Stadler, Peter (American Society for Microbiology, 2003-03)
    • Itaconate and derivatives reduce interferon responses and inflammation in influenza A virus infection.

      Sohail, Aaqib; Iqbal, Azeem A; Sahini, Nishika; Chen, Fangfang; Tantawy, Mohamed; Waqas, Fakhar; Winterhoff, Moritz; Ebensen, Thomas; Schultz, Kristin; Geffers, Robert; et al. (PLOS, 2022-01-13)
      Excessive inflammation is a major cause of morbidity and mortality in many viral infections including influenza. Therefore, there is a need for therapeutic interventions that dampen and redirect inflammatory responses and, ideally, exert antiviral effects. Itaconate is an immunomodulatory metabolite which also reprograms cell metabolism and inflammatory responses when applied exogenously. We evaluated effects of endogenous itaconate and exogenous application of itaconate and its variants dimethyl- and 4-octyl-itaconate (DI, 4OI) on host responses to influenza A virus (IAV). Infection induced expression of ACOD1, the enzyme catalyzing itaconate synthesis, in monocytes and macrophages, which correlated with viral replication and was abrogated by DI and 4OI treatment. In IAV-infected mice, pulmonary inflammation and weight loss were greater in Acod1-/- than in wild-type mice, and DI treatment reduced pulmonary inflammation and mortality. The compounds reversed infection-triggered interferon responses and modulated inflammation in human cells supporting non-productive and productive infection, in peripheral blood mononuclear cells, and in human lung tissue. Itaconates reduced ROS levels and STAT1 phosphorylation, whereas AKT phosphorylation was reduced by 4OI and DI but increased by itaconate. Single-cell RNA sequencing identified monocytes as the main target of infection and the exclusive source of ACOD1 mRNA in peripheral blood. DI treatment silenced IFN-responses predominantly in monocytes, but also in lymphocytes and natural killer cells. Ectopic synthesis of itaconate in A549 cells, which do not physiologically express ACOD1, reduced infection-driven inflammation, and DI reduced IAV- and IFNγ-induced CXCL10 expression in murine macrophages independent of the presence of endogenous ACOD1. The compounds differed greatly in their effects on cellular gene homeostasis and released cytokines/chemokines, but all three markedly reduced release of the pro-inflammatory chemokines CXCL10 (IP-10) and CCL2 (MCP-1). Viral replication did not increase under treatment despite the dramatically repressed IFN responses. In fact, 4OI strongly inhibited viral transcription in peripheral blood mononuclear cells, and the compounds reduced viral titers (4OI>Ita>DI) in A549 cells whereas viral transcription was unaffected. Taken together, these results reveal itaconates as immunomodulatory and antiviral interventions for influenza virus infection.
    • Key features and homing properties of NK cells in the liver are shaped by activated iNKT cells.

      Trittel, Stephanie; Chambers, Benedict J; Heise, Ulrike; Guzmán, Carlos A; Riese, Peggy; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Springer-Nature, 2019-11-08)
      The contribution of natural killer (NK) cells to the clearance of hepatic viral infections is well recognized. The recently discovered heterogeneity of NK cell populations renders them interesting targets for immune interventions. Invariant natural killer T (iNKT) cells represent a key interaction partner for hepatic NK cells. The present study addressed whether characteristics of NK cells in the liver can be shaped by targeting iNKT cells. For this, the CD1d-binding pegylated glycolipid αGalCerMPEG was assessed for its ability to modulate the features of NK cells permanently or transiently residing in the liver. In vivo administration resulted in enhanced functionality of educated and highly differentiated CD27+ Mac-1+ NK cells accompanied by an increased proliferation. Improved liver homing was supported by serum-derived and cellular factors. Reduced viral loads in a mCMV infection model confirmed the beneficial effect of NK cells located in the liver upon stimulation with αGalCerMPEG. Thus, targeting iNKT cell-mediated NK cell activation in the liver represents a promising approach for the establishment of liver-directed immune interventions.
    • Knockdown of Virus Antigen Expression Increases Therapeutic Vaccine Efficacy in High-titer HBV Carrier Mice.

      Michler, Thomas; Kosinska, Anna D; Festag, Julia; Bunse, Till; Su, Jinpeng; Ringelhan, Marc; Imhof, Hortenzia; Grimm, Dirk; Steiger, Katja; Mogler, Carolin; et al. (Elsevier, 2020-01-28)
      In both models of HBV infection, mice that express hepatocyte-specific small hairpin RNAs or that were given subcutaneous injections of siRNAs had reduced levels of HBV antigens, HBV replication, and viremia (1-3 log10 reduction), compared to mice given control RNAs. Vaccination induced production of HBV-neutralizing antibodies, and increased numbers and functionality of HBV-specific, CD8+ T-cells in mice with low, but not in mice with high levels of HBV antigen. Mice with initially high titers of HBV and knockdown of HBV antigen expression, but not mice with reduced viremia following administration of entecavir, developed polyfunctional, HBV-specific CD8+ T cells and HBV was eliminated.
    • Lactobacillus reuteri DSM 20016 produces cobalamin-dependent diol dehydratase in metabolosomes and metabolizes 1,2-propanediol by disproportionation.

      Sriramulu, Dinesh Diraviam; Liang, Mingzhi; Hernandez-Romero, Diana; Raux-Deery, Evelyne; Lünsdorf, Heinrich; Parsons, Joshua B; Warren, Martin J; Prentice, Michael B; Department of Microbiology, University College Cork, Cork, Ireland. (2008-07)
      A Lactobacillus reuteri strain isolated from sourdough is known to produce the vitamin cobalamin. The organism requires this for glycerol cofermentation by a cobalamin-dependent enzyme, usually termed glycerol dehydratase, in the synthesis of the antimicrobial substance reuterin. We show that the cobalamin-synthesizing capacity of another L. reuteri strain (20016, the type strain, isolated from the human gut and recently sequenced as F275) is genetically and phenotypically linked, as in the Enterobacteriaceae, to the production of a cobalamin-dependent enzyme which is associated with a bacterial microcompartment (metabolosome) and known as diol dehydratase. We show that this enzyme allows L. reuteri to carry out a disproportionation reaction converting 1,2-propanediol to propionate and propanol. The wide distribution of this operon suggests that it is adapted to horizontal transmission between bacteria. However, there are significant genetic and phenotypic differences between the Lactobacillus background and the Enterobacteriaceae. Electron microscopy reveals that the bacterial microcompartment in L. reuteri occupies a smaller percentage of the cytoplasm than in gram-negative bacteria. DNA sequence data show evidence of a regulatory control mechanism different from that in gram-negative bacteria, with the presence of a catabolite-responsive element (CRE) sequence immediately upstream of the pdu operon encoding diol dehydratase and metabolosome structural genes in L. reuteri. The metabolosome-associated diol dehydratase we describe is the only candidate glycerol dehydratase present on inspection of the L. reuteri F275 genome sequence.
    • Large-scale production of megakaryocytes in microcarrier-supported stirred suspension bioreactors.

      Eicke, Dorothee; Baigger, Anja; Schulze, Kai; Latham, Sharissa L; Halloin, Caroline; Zweigerdt, Robert; Guzman, Carlos A; Blasczyk, Rainer; Figueiredo, Constança; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-07-05)
      Megakaryocytes (MKs) are the precursors of platelets (PLTs) and may be used for PLT production in vivo or in vitro, as well as a source for PLT-derived growth factors. Induced pluripotent stem cells represent an unlimited cell source for the in vitro production of MKs. This study aimed at developing an effective, xeno-free and scalable system to produce high numbers of MKs. In particular, microcarrier beads-assisted stirred bioreactors were evaluated as a means of improving MK yields. This method resulted in the production of 18.7 × 10
    • Local treatment with BPPcysMPEG reduces allergic airway inflammation in sensitized mice.

      Knothe, S; Mutschler, V; Rochlitzer, S; Winkler, C; Ebensen, T; Guzman, C A; Hohlfeld, J; Braun, A; Muller, M; Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Department of Immunology, Allergology and Immunotoxicology, Hannover, Germany. (2011-07-07)
      According to the hygiene hypothesis, triggering the immune system with microbial components during childhood balances the inherent Th2 bias. In contrast, specific immunotherapy involves exposure of the patient to the allergen in order to achieve desensitization to subsequent contact. In a human in vitro allergy model the potential of the TLR2/6 agonist BPPcysMPEG to modulate antigen presenting cells and allergen-specific immune responses was evaluated. Specific immunomodulation via co-administration of the allergen and BPPcysMPEG enhanced expression of co-stimulatory molecules on DC and increased secretion of the proinflammatory cytokine TNF-α. Acting as an adjuvant, BPPcysMPEG elevated allergen-specific immune responses in co-culture with autologous lymphocytes. Although administration of BPPcysMPEG alone enhanced expression of co-stimulatory molecules on DC, proliferation of autologous lymphocytes was not induced. Based on this finding, the potential of BPPcysMPEG to reduce allergic airway inflammation by preventive modulation of the innate immune system via TLR2/6 agonization was investigated in mice. Local administration of BPPcysMPEG altered cellular influx and cell composition in BAL fluid. Furthermore, the Th2-associated cytokines IL-4 and IL-5 were diminished. Allergen-specific restimulation of cells from mediastinal lymph nodes and splenocytes suggested an alteration of immune responses. The treatment with BPPcysMPEG induced a Th1-dominated cytokine milieu in mediastinal lymph nodes, while allergen-specific immune responses in splenocytes were diminished. The co-administration of allergen and BPPcysMPEG reduced cytokine secretion upon restimulation in mediastinal lymph nodes and splenocytes. From these data we conclude that BPPcysMPEG was able to influence the immune system with regard to subsequent allergen contact by TLR2/6 agonization.
    • Long-term effects of ocean warming on the prokaryotic community: evidence from the vibrios.

      Vezzulli, Luigi; Brettar, Ingrid; Pezzati, Elisabetta; Reid, Philip C; Colwell, Rita R; Höfle, Manfred G; Pruzzo, Carla; Department for the Study of Territory and its Resources, University of Genoa, Genoa, Italy. luigi.vezzulli@unige.it (2012-01)
      The long-term effects of ocean warming on prokaryotic communities are unknown because of lack of historical data. We overcame this gap by applying a retrospective molecular analysis to the bacterial community on formalin-fixed samples from the historical Continuous Plankton Recorder archive, which is one of the longest and most geographically extensive collections of marine biological samples in the world. We showed that during the last half century, ubiquitous marine bacteria of the Vibrio genus, including Vibrio cholerae, increased in dominance within the plankton-associated bacterial community of the North Sea, where an unprecedented increase in bathing infections related to these bacteria was recently reported. Among environmental variables, increased sea surface temperature explained 45% of the variance in Vibrio data, supporting the view that ocean warming is favouring the spread of vibrios and may be the cause of the globally increasing trend in their associated diseases.
    • Microevolution of pandemic Vibrio parahaemolyticus assessed by the number of repeat units in short sequence tandem repeat regions.

      García, Katherine; Gavilán, Ronnie G; Höfle, Manfred G; Martínez-Urtaza, Jaime; Espejo, Romilio T; Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile. (2012)
      The emergence of the pandemic strain Vibrio parahaemolyticus O3:K6 in 1996 caused a large increase of diarrhea outbreaks related to seafood consumption in Southeast Asia, and later worldwide. Isolates of this strain constitutes a clonal complex, and their effectual differentiation is possible by comparison of their variable number tandem repeats (VNTRs). The differentiation of the isolates by the differences in VNTRs will allow inferring the population dynamics and microevolution of this strain but this requires knowing the rate and mechanism of VNTRs' variation. Our study of mutants obtained after serial cultivation of clones showed that mutation rates of the six VNTRs examined are on the order of 10(-4) mutant per generation and that difference increases by stepwise addition of single mutations. The single stepwise mutation (SSM) was deduced because mutants with 1, 2, 3, or more repeat unit deletions or insertions follow a geometric distribution. Plausible phylogenetic trees are obtained when, according to SSM, the genetic distance between clusters with different number of repeats is assessed by the absolute differences in repeats. Using this approach, mutants originated from different isolates of pandemic V. parahaemolyticus after serial cultivation are clustered with their parental isolates. Additionally, isolates of pandemic V. parahaemolyticus from Southeast Asia, Tokyo, and northern and southern Chile are clustered according their geographical origin. The deepest split in these four populations is observed between the Tokyo and southern Chile populations. We conclude that proper phylogenetic relations and successful tracing of pandemic V. parahaemolyticus requires measuring the differences between isolates by the absolute number of repeats in the VNTRs considered.
    • The missing link: Bordetella petrii is endowed with both the metabolic versatility of environmental bacteria and virulence traits of pathogenic Bordetellae.

      Gross, Roy; Guzman, Carlos A; Sebaihia, Mohammed; dos Santos, Vítor A P Martins; Pieper, Dietmar H; Koebnik, Ralf; Lechner, Melanie; Bartels, Daniela; Buhrmester, Jens; Choudhuri, Jomuna V; et al. (2008)
      BACKGROUND: Bordetella petrii is the only environmental species hitherto found among the otherwise host-restricted and pathogenic members of the genus Bordetella. Phylogenetically, it connects the pathogenic Bordetellae and environmental bacteria of the genera Achromobacter and Alcaligenes, which are opportunistic pathogens. B. petrii strains have been isolated from very different environmental niches, including river sediment, polluted soil, marine sponges and a grass root. Recently, clinical isolates associated with bone degenerative disease or cystic fibrosis have also been described. RESULTS: In this manuscript we present the results of the analysis of the completely annotated genome sequence of the B. petrii strain DSMZ12804. B. petrii has a mosaic genome of 5,287,950 bp harboring numerous mobile genetic elements, including seven large genomic islands. Four of them are highly related to the clc element of Pseudomonas knackmussii B13, which encodes genes involved in the degradation of aromatics. Though being an environmental isolate, the sequenced B. petrii strain also encodes proteins related to virulence factors of the pathogenic Bordetellae, including the filamentous hemagglutinin, which is a major colonization factor of B. pertussis, and the master virulence regulator BvgAS. However, it lacks all known toxins of the pathogenic Bordetellae. CONCLUSION: The genomic analysis suggests that B. petrii represents an evolutionary link between free-living environmental bacteria and the host-restricted obligate pathogenic Bordetellae. Its remarkable metabolic versatility may enable B. petrii to thrive in very different ecological niches.
    • Mitochondrial Ca²⁺ and membrane potential, an alternative pathway for Interleukin 6 to regulate CD4 cell effector function.

      Yang, Rui; Lirussi, Dario; Thornton, Tina M; Jelley-Gibbs, Dawn M; Diehl, Sean A; Case, Laure K; Madesh, Muniswamy; Taatjes, Douglas J; Teuscher, Cory; Haynes, Laura; et al. (2015)
      IL-6 plays an important role in determining the fate of effector CD4 cells and the cytokines that these cells produce. Here we identify a novel molecular mechanism by which IL-6 regulates CD4 cell effector function. We show that IL-6-dependent signal facilitates the formation of mitochondrial respiratory chain supercomplexes to sustain high mitochondrial membrane potential late during activation of CD4 cells. Mitochondrial hyperpolarization caused by IL-6 is uncoupled from the production of ATP by oxidative phosphorylation. However, it is a mechanism to raise the levels of mitochondrial Ca(2+) late during activation of CD4 cells. Increased levels of mitochondrial Ca(2+) in the presence of IL-6 are used to prolong Il4 and Il21 expression in effector CD4 cells. Thus, the effect of IL-6 on mitochondrial membrane potential and mitochondrial Ca(2+) is an alternative pathway by which IL-6 regulates effector function of CD4 cells and it could contribute to the pathogenesis of inflammatory diseases.
    • Modified vaccinia virus Ankara exerts potent immune modulatory activities in a murine model.

      Nörder, Miriam; Becker, Pablo D; Drexler, Ingo; Link, Claudia; Erfle, Volker; Guzmán, Carlos A; Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany. (2010)
      BACKGROUND: Modified vaccinia virus Ankara (MVA), a highly attenuated strain of vaccinia virus, has been used as vaccine delivery vector in preclinical and clinical studies against infectious diseases and malignancies. Here, we investigated whether an MVA which does not encode any antigen (Ag) could be exploited as adjuvant per se. METHODOLOGY/PRINCIPAL FINDINGS: We showed that dendritic cells infected in vitro with non-recombinant (nr) MVA expressed maturation and activation markers and were able to efficiently present exogenously pulsed Ag to T cells. In contrast to the dominant T helper (Th) 1 biased responses elicited against Ags produced by recombinant MVA vectors, the use of nrMVA as adjuvant for the co-administered soluble Ags resulted in a long lasting mixed Th1/Th2 responses. CONCLUSIONS/SIGNIFICANCE: These findings open new ways to potentiate and modulate the immune responses to vaccine Ags depending on whether they are co-administered with MVA or encoded by recombinant viruses.
    • Modulation of chemokine gene expression by Shiga-toxin producing Escherichia coli belonging to various origins and serotypes.

      Gobert, Alain P; Coste, Alix; Guzman, Carlos A; Vareille, Marjolaine; Hindré, Thomas; de Sablet, Thibaut; Girardeau, Jean-Pierre; Martin, Christine; Institut National de la Recherche Agronomique (INRA), UR454 Unité de Microbiologie, Centre de Theix, 63122 Saint-Genès-Champanelle, France. (2008-02)
      Infection with Shiga-toxin producing Escherichia coli (STEC) may result in the development of the haemolytic-uremic syndrome (HUS), the main cause of acute renal failure in children. While O157:H7 STEC are associated with large outbreaks of HUS, it is difficult to predict whether a non-O157:H7 isolate can be pathogenic for humans. The mucosal innate immune response plays a central role in the pathogenesis of HUS; therefore, we compared the induction of IL-8 and CCL20 in human colon epithelial cells infected with strains belonging to different serotypes, isolated from cattle or from HUS patients. No correlation was observed between strain virulence and chemokine gene expression. Rather, the genetic background of the strains seems to determine the chemokine gene expression profile. Investigating the contribution of different bacterial factors in this process, we show that the type III secretion system of O157:H7 bacteria, but not the intimate adhesion, is required to stimulate the cells. In addition, H7, H10, and H21 flagellins are potent inducers of chemokine gene expression when synthesized in large amount.
    • Monte Carlo Simulation of SARS-CoV-2 Radiation-Induced Inactivation for Vaccine Development.

      Francis, Ziad; Incerti, Sebastien; Zein, Sara A; Lampe, Nathanael; Guzman, Carlos A; Durante, Marco; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Radiation Research Society, 2021-01-07)
      Immunization with an inactivated virus is one of the strategies currently being tested towards developing a SARS-CoV-2 vaccine. One of the methods used to inactivate viruses is exposure to high doses of ionizing radiation to damage their nucleic acids. While gamma (γ) rays effectively induce lesions in the RNA, envelope proteins are also highly damaged in the process. This in turn may alter their antigenic properties, affecting their capacity to induce an adaptive immune response able to confer effective protection. Here, we modeled the effect of sparsely and densely ionizing radiation on SARS-CoV-2 using the Monte Carlo toolkit Geant4-DNA. With a realistic 3D target virus model, we calculated the expected number of lesions in the spike and membrane proteins, as well as in the viral RNA. Our findings showed that γ rays produced significant spike protein damage, but densely ionizing charged particles induced less membrane damage for the same level of RNA lesions, because a single ion traversal through the nuclear envelope was sufficient to inactivate the virus. We propose that accelerated charged particles produce inactivated viruses with little structural damage to envelope proteins, thereby representing a new and effective tool for developing vaccines against SARS-CoV-2 and other enveloped viruses.
    • The Mucosal Adjuvant Cyclic di-AMP Exerts Immune Stimulatory Effects on Dendritic Cells and Macrophages.

      Skrnjug, Ivana; Rueckert, Christine; Libanova, Rimma; Lienenklaus, Stefan; Weiss, Siegfried; Guzmán, Carlos A (2014)
      The cyclic di-nucleotide bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) is a candidate mucosal adjuvant with proven efficacy in preclinical models. It was shown to promote specific humoral and cellular immune responses following mucosal administration. To date, there is only fragmentary knowledge on the cellular and molecular mode of action of c-di-AMP. Here, we report on the identification of dendritic cells and macrophages as target cells of c-di-AMP. We show that c-di-AMP induces the cell surface up-regulation of T cell co-stimulatory molecules as well as the production of interferon-β. Those responses were characterized by in vitro experiments with murine and human immune cells and in vivo studies in mice. Analyses of dendritic cell subsets revealed conventional dendritic cells as principal responders to stimulation by c-di-AMP. We discuss the impact of the reported antigen presenting cell activation on the previously observed adjuvant effects of c-di-AMP in mouse immunization studies.