Publications by authors named "Carlos A Guzman"

183 Publications

Advanced strategies for development of vaccines against human bacterial pathogens.

World J Microbiol Biotechnol 2021 Mar 22;37(4):67. Epub 2021 Mar 22.

School of Life Sciences, Jawaharlal Nehru University, Aruna Asaf Ali Marg, New Delhi, 110067, India.

Infectious diseases are one of the main grounds of death and disabilities in human beings globally. Lack of effective treatment and immunization for many deadly infectious diseases and emerging drug resistance in pathogens underlines the need to either develop new vaccines or sufficiently improve the effectiveness of currently available drugs and vaccines. In this review, we discuss the application of advanced tools like bioinformatics, genomics, proteomics and associated techniques for a rational vaccine design.
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http://dx.doi.org/10.1007/s11274-021-03021-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7982316PMC
March 2021

Self-Amplifying Pestivirus Replicon RNA Encoding Influenza Virus Nucleoprotein and Hemagglutinin Promote Humoral and Cellular Immune Responses in Pigs.

Front Immunol 2020 28;11:622385. Epub 2021 Jan 28.

The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.

Self-amplifying replicon RNA (RepRNA) promotes expansion of mRNA templates encoding genes of interest through their replicative nature, thus providing increased antigen payloads. RepRNA derived from the non-cytopathogenic classical swine fever virus (CSFV) targets monocytes and dendritic cells (DCs), potentially promoting prolonged antigen expression in the DCs, contrasting with cytopathogenic RepRNA. We engineered pestivirus RepRNA constructs encoding influenza virus H5N1 (A/chicken/Yamaguchi/7/2004) nucleoprotein (Rep-NP) or hemagglutinin (Rep-HA). The inherent RNase-sensitivity of RepRNA had to be circumvented to ensure efficient delivery to DCs for intracellular release and RepRNA translation; we have reported how only particular synthetic delivery vehicle formulations are appropriate. The question remained concerning RepRNA packaged in virus replicon particles (VRPs); we have now compared an efficient polyethylenimine (PEI)-based formulation (polyplex) with VRP-delivery as well as naked RepRNA co-administered with the potent bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) adjuvant. All formulations contained a Rep-HA/Rep-NP mix, to assess the breadth of both humoral and cell-mediated defences against the influenza virus antigens. Assessment employed pigs for their close immunological relationship to humans, and as natural hosts for influenza virus. Animals receiving the VRPs, as well as PEI-delivered RepRNA, displayed strong humoral and cellular responses against both HA and NP, but with VRPs proving to be more efficacious. In contrast, naked RepRNA plus c-di-AMP could induce only low-level immune responses, in one out of five pigs. In conclusion, RepRNA encoding different influenza virus antigens are efficacious for inducing both humoral and cellular immune defences in pigs. Comparisons showed that packaging within VRP remains the most efficacious for delivery leading to induction of immune defences; however, this technology necessitates employment of expensive complementing cell cultures, and VRPs do not target human cells. Therefore, choosing the appropriate synthetic delivery vehicle still offers potential for rapid vaccine design, particularly in the context of the current coronavirus pandemic.
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http://dx.doi.org/10.3389/fimmu.2020.622385DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7877248PMC
February 2021

Cyclic Di-Adenosine Monophosphate: A Promising Adjuvant Candidate for the Development of Neonatal Vaccines.

Pharmaceutics 2021 Feb 1;13(2). Epub 2021 Feb 1.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.

Underdeveloped immunity during the neonatal age makes this period one of the most dangerous during the human lifespan, with infection-related mortality being one of the highest of all age groups. It is also discussed that vaccination during this time window may result in tolerance rather than in productive immunity, thus raising concerns about the overall vaccine-mediated protective efficacy. Cyclic di-nucleotides (CDN) are bacterial second messengers that are rapidly sensed by the immune system as a danger signal, allowing the utilization of these molecules as potent activators of the immune response. We have previously shown that cyclic di-adenosine monophosphate (CDA) is a potent and versatile adjuvant capable of promoting humoral and cellular immunity. We characterize here the cytokine profiles elicited by CDA in neonatal cord blood in comparison with other promising neonatal adjuvants, such as the imidazoquinoline resiquimod (R848), which is a synthetic dual TLR7 and TLR8 agonist. We observed superior activity of CDA in eliciting T helper 1 (Th1) and T follicular helper (TfH) cytokines in cells from human cord blood when compared to R848. Additional in vivo studies in mice showed that neonatal priming in a three-dose vaccination schedule is beneficial when CDA is used as a vaccine adjuvant. Humoral antibody titers were significantly higher in mice that received a neonatal prime as compared to those that did not. This effect was absent when using other adjuvants that were reported as suitable for neonatal vaccination. The biological significance of this immune response was assessed by a challenge with a genetically modified influenza H1N1 PR8 virus. The obtained results confirmed that CDA performed better than any other adjuvant tested. Altogether, our results suggest that CDA is a potent adjuvant in vitro on human cord blood, and in vivo in newborn mice, and thus a suitable candidate for the development of neonatal vaccines.
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http://dx.doi.org/10.3390/pharmaceutics13020188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7912751PMC
February 2021

Monte Carlo Simulation of SARS-CoV-2 Radiation-Induced Inactivation for Vaccine Development.

Radiat Res 2021 03;195(3):221-229

GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany.

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.
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http://dx.doi.org/10.1667/RADE-20-00241.1DOI Listing
March 2021

Towards Reduction or Substitution of Cytotoxic DMSO in Biobanking of Functional Bioengineered Megakaryocytes.

Int J Mol Sci 2020 Oct 16;21(20). Epub 2020 Oct 16.

Institute of Transfusion Medicine and Transplant Engineering, Hannover Medical School, 30625 Hannover, Germany.

Donor platelet transfusion is currently the only efficient treatment of life-threatening thrombocytopenia, but it is highly challenged by immunological, quality, and contamination issues, as well as short shelf life of the donor material. Ex vivo produced megakaryocytes and platelets represent a promising alternative strategy to the conventional platelet transfusion. However, practical implementation of such strategy demands availability of reliable biobanking techniques, which would permit eliminating continuous cell culture maintenance, ensure time for quality testing, enable stock management and logistics, as well as availability in a ready-to-use manner. At the same time, protocols applying DMSO-based cryopreservation media were associated with increased risks of adverse long-term side effects after patient use. Here, we show the possibility to develop cryopreservation techniques for iPSC-derived megakaryocytes under defined xeno-free conditions with significant reduction or complete elimination of DMSO. Comprehensive phenotypic and functional in vitro characterization of megakaryocytes has been performed before and after cryopreservation. Megakaryocytes cryopreserved DMSO-free, or using low DMSO concentrations, showed the capability to produce platelets in vivo after transfusion in a mouse model. These findings propose biobanking approaches essential for development of megakaryocyte-based replacement and regenerative therapies.
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http://dx.doi.org/10.3390/ijms21207654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589913PMC
October 2020

Practical and Ethical Solutions for Remote Applied Learning Experiences in Global Health.

Ann Glob Health 2020 08 19;86(1):103. Epub 2020 Aug 19.

Johns Hopkins University, Johns Hopkins Center for Global Health, Baltimore, MD, US.

Global health trainees rely on immersive experiences to apply their classroom knowledge in real-world settings. However, during the COVID-19 pandemic travel has come to a halt and short-term experiences are no longer available in their current form. As with didactic material, global health programs have an opportunity to innovate the delivery of applied learning, providing trainees with robust, mentored experiences that promote the acquisition of core global health competencies. We provide a series of practical solutions for remote applied learning including case-based learning, pathfinder pedagogy, virtual reality simulations, and twinning. We further describe the role of these approaches in addressing common criticisms of short-term experiences and their potential for creating new win-win dynamics between institutions and trainees.
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http://dx.doi.org/10.5334/aogh.2999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442166PMC
August 2020

Seropositivity for pathogens associated with chronic infections is a risk factor for all-cause mortality in the elderly: findings from the Memory and Morbidity in Augsburg Elderly (MEMO) Study.

Geroscience 2020 10 9;42(5):1365-1376. Epub 2020 Jul 9.

Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany.

Immunostimulation by chronic infection has been linked to an increased risk for different non-communicable diseases, which in turn are leading causes of death in high- and middle-income countries. Thus, we investigated if a positive serostatus for pathogens responsible for common chronic infections is individually or synergistically related to reduced overall survival in community dwelling elderly. We used data of 365 individuals from the German MEMO (Memory and Morbidity in Augsburg Elderly) cohort study with a median age of 73 years at baseline and a median follow-up of 14 years. We examined the effect of a positive serostatus at baseline for selected pathogens associated with chronic infections (Helicobacter pylori, Borrelia burgdorferi sensu lato, Toxoplasma gondii, cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1/2, and human herpesvirus 6) on all-cause mortality with multivariable parametric survival models. We found a reduced survival time in individuals with a positive serostatus for Helicobacter pylori (accelerated failure time (AFT) - 15.92, 95% CI - 29.96; - 1.88), cytomegalovirus (AFT - 22.81, 95% CI - 36.41; - 9.22) and Borrelia burgdorferi sensu lato (AFT - 25.25, 95% CI - 43.40; - 7.10), after adjusting for potential confounders. The number of infectious agents an individual was seropositive for had a linear effect on all-cause mortality (AFT per additional infection - 12.42 95% CI - 18.55; - 6.30). Our results suggest an effect of seropositivity for Helicobacter pylori, cytomegalovirus, and Borrelia burgdorferi sensu lato on all-cause mortality in older community dwelling individuals. Further research with larger cohorts and additional biomarkers is required, to assess mediators and molecular pathways of this effect.
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http://dx.doi.org/10.1007/s11357-020-00216-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7525922PMC
October 2020

P. aeruginosa Infected 3D Co-Culture of Bronchial Epithelial Cells and Macrophages at Air-Liquid Interface for Preclinical Evaluation of Anti-Infectives.

J Vis Exp 2020 06 15(160). Epub 2020 Jun 15.

Department of Drug Delivery, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS); Department of Pharmacy, Saarland University;

fDrug research for the treatment of lung infections is progressing towards predictive in vitro models of high complexity. The multifaceted presence of bacteria in lung models can re-adapt epithelial arrangement, while immune cells coordinate an inflammatory response against the bacteria in the microenvironment. While in vivo models have been the choice for testing new anti-infectives in the context of cystic fibrosis, they still do not accurately mimic the in vivo conditions of such diseases in humans and the treatment outcomes. Complex in vitro models of the infected airways based on human cells (bronchial epithelial and macrophages) and relevant pathogens could bridge this gap and facilitate the translation of new anti-infectives into the clinic. For such purposes, a co-culture model of the human cystic fibrosis bronchial epithelial cell line CFBE41o and THP-1 monocyte-derived macrophages has been established, mimicking an infection of the human bronchial mucosa by P. aeruginosa at air-liquid interface (ALI) conditions. This model is set up in seven days, and the following parameters are simultaneously assessed: epithelial barrier integrity, macrophage transmigration, bacterial survival, and inflammation. The present protocol describes a robust and reproducible system for evaluating drug efficacy and host responses that could be relevant for discovering new anti-infectives and optimizing their aerosol delivery to the lungs.
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http://dx.doi.org/10.3791/61069DOI Listing
June 2020

Responsiveness to Influenza Vaccination Correlates with NKG2C-Expression on NK Cells.

Vaccines (Basel) 2020 Jun 5;8(2). Epub 2020 Jun 5.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany.

Influenza vaccination often results in a large percentage of low responders, especially in high-risk groups. As a first line of defense, natural killer (NK) cells play a crucial role in the fight against infections. However, their implication with regard to vaccine responsiveness is insufficiently assessed. Therefore, this study aimed at the validation of essential NK cell features potentially associated with differential vaccine responsiveness with a special focus on NKG2C- and/or CD57-expressing NK cells considered to harbor memory-like functions. To this end, 16 healthy volunteers were vaccinated with an adjuvanted pandemic influenza vaccine. Vaccine responders and low responders were classified according to their hemagglutination inhibition antibody titers. A majority of responders displayed enhanced frequencies of NKG2C-expressing NK cells 7- or 14-days post-vaccination as compared to low responders, whereas the expression of CD57 was not differentially modulated. The NK cell cytotoxic potential was found to be confined to CD56CD16 NKG2C-expressing NK cells in the responders but not in the low responders, which was further confirmed by stochastic neighbor embedding analysis. The presented study is the first of its kind that ascribes CD56CD16 NKG2C-expressing NK cells a crucial role in biasing adaptive immune responses upon influenza vaccination and suggests NKG2C as a potential biomarker in predicting pandemic influenza vaccine responsiveness.
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http://dx.doi.org/10.3390/vaccines8020281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349951PMC
June 2020

Integrating Competency-Based Didactic and Experiential Global Health Learning for Dental Students: The Global Health Learning Helix Model.

J Dent Educ 2020 Apr;84(4):438-448

The aim of this study was to evaluate the feasibility and preliminary outcomes of immersive integrated experiential and didactic courses in strengthening competency-based global health learning in dental education. To address global inequities in oral health and student interest in global health, the Harvard School of Dental Medicine introduced two global health courses in 2017-18. The first was a didactic course in the core predoctoral curriculum, and the second, in collaboration with the Inter-American Center for Global Health, was a five-day elective experiential learning course in rural Costa Rica. The experiential course was an extension of the didactic course. All 33 second-year dental students completed the didactic course, and three of those students completed the experiential course. A pre-post survey and a six-month follow-up survey on self-reported knowledge based on course learning objectives were administered. The experiential course students also completed journals and interviews for qualitative analysis. Thirty-two students completed the pre-post didactic course surveys, for a response rate of 94%. There was a 100% response rate on the pre-post didactic surveys by those students who participated in the experiential learning course. While the experiential learning group scored similarly to the class average before the didactic course, they had higher scores than the class averages both immediately after and at the six-month follow-up. All three students reported that the experiential learning course was "extremely effective" in building on what they learned in the didactic course. Qualitative analysis of the journals and interviews suggested enhanced learning from the combination of didactic and experiential methods. These preliminary results support the Global Health Learning Helix Model, a theoretical competency-based teaching model for ethical student global health engagement to better prepare the future generation in tackling oral health disparities both locally and worldwide.
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http://dx.doi.org/10.21815/JDE.019.186DOI Listing
April 2020

Role of Autophagy in Von Willebrand Factor Secretion by Endothelial Cells and in the In Vivo Thrombin-Antithrombin Complex Formation Promoted by the HIV-1 Matrix Protein p17.

Int J Mol Sci 2020 Mar 16;21(6). Epub 2020 Mar 16.

Department of Molecular and Translational Medicine, Section of Microbiology, University of Brescia Medical School, 25123 Brescia, Italy.

Although the advent of combined antiretroviral therapy has substantially improved the survival of HIV-1-infected individuals, non-AIDS-related diseases are becoming increasingly prevalent in HIV-1-infected patients. Persistent abnormalities in coagulation appear to contribute to excess risk for a broad spectrum of non-AIDS defining complications. Alterations in coagulation biology in the context of HIV infection seem to be largely a consequence of a chronically inflammatory microenvironment leading to endothelial cell (EC) dysfunction. A possible direct role of HIV-1 proteins in sustaining EC dysfunction has been postulated but not yet investigated. The HIV-1 matrix protein p17 (p17) is secreted from HIV-1-infected cells and is known to sustain inflammatory processes by activating ECs. The aim of this study was to investigate the possibility that p17-driven stimulation of human ECs is associated with increased production of critical coagulation factors. Here we show the involvement of autophagy in the p17-induced accumulation and secretion of von Willebrand factor (vWF) by ECs. In vivo experiments confirmed the capability of p17 to exert a potent pro-coagulant activity soon after its intravenous administration.
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http://dx.doi.org/10.3390/ijms21062022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7139864PMC
March 2020

Mucosal Heterologous Prime/Boost Vaccination Induces Polyfunctional Systemic Immunity, Improving Protection Against .

Front Immunol 2020 21;11:128. Epub 2020 Feb 21.

Facultad de Farmacia y Bioquímica, Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral "Prof. Ricardo A. Margni" (IDEHU), UBA-CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.

There are several unmet needs in modern immunology. Among them, vaccines against parasitic diseases and chronic infections lead. , the causative agent of Chagas disease, is an excellent example of a silent parasitic invasion that affects millions of people worldwide due to its progression into the symptomatic chronic phase of infection. In search for novel vaccine candidates, we have previously introduced Traspain, an engineered trivalent immunogen that was designed to address some of the known mechanisms of immune evasion. Here, we analyzed its performance in different DNA prime/protein boost protocols and characterized the systemic immune response associated with diverse levels of protection. Formulations that include a STING agonist, like c-di-AMP in the boost doses, were able to prime a Th1/Th17 immune response. Moreover, comparison between them showed that vaccines that were able to prime polyfunctional cell-mediated immunity at the CD4 and CD8 compartment enhanced protection levels in the murine model. These findings contribute to a better knowledge of the desired vaccine-elicited immunity against and promote the definition of a vaccine correlate of protection against the infection.
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http://dx.doi.org/10.3389/fimmu.2020.00128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047160PMC
March 2021

ADAP Promotes Degranulation and Migration of NK Cells Primed During Infection in Mice.

Front Immunol 2019 22;10:3144. Epub 2020 Jan 22.

Infection Immunology Group, Institute of Medical Microbiology, Infection Control and Prevention, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.

The adhesion and degranulation-promoting adaptor protein (ADAP) serves as a multifunctional scaffold and is involved in the formation of immune signaling complexes. To date only limited and moreover conflicting data exist regarding the role of ADAP in NK cells. To extend existing knowledge we investigated ADAP-dependency of NK cells in the context of infection with the intracellular pathogen (). analysis of infection-primed NK cells revealed impaired cytotoxic capacity in NK cells lacking ADAP as indicated by reduced CD107a surface expression and inefficient perforin production. However, ADAP-deficiency had no global effect on NK cell morphology or intracellular distribution of CD107a-containing vesicles. Proteomic definition of ADAPko and wild type NK cells did not uncover obvious differences in protein composition during the steady state and moreover, similar early response patterns were induced in NK cells upon infection independent of the genotype. In line with protein network analyses that suggested an altered migration phenotype in naïve ADAPko NK cells, migration assays uncovered significantly reduced migration of both naïve as well as infection-primed ADAPko NK cells compared to wild type NK cells. Notably, this migration defect was associated with a significantly reduced expression of the integrin CD11a on the surface of splenic ADAP-deficient NK cells 1 day post- infection. We propose that ADAP-dependent alterations in integrin expression might account at least in part for the fact that during infection significantly lower numbers of ADAPko NK cells accumulate in the spleen i.e., the site of infection. In conclusion, we show here that during systemic infection in mice ADAP is essential for efficient cytotoxic capacity and migration of NK cells.
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http://dx.doi.org/10.3389/fimmu.2019.03144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987423PMC
November 2020

Knockdown of Virus Antigen Expression Increases Therapeutic Vaccine Efficacy in High-Titer Hepatitis B Virus Carrier Mice.

Gastroenterology 2020 05 28;158(6):1762-1775.e9. Epub 2020 Jan 28.

Institute of Virology, Technical University of Münich, Helmholtz Zentrum München, Münich, Germany; German Center for Infection Research, Münich, Heidelberg, Germany. Electronic address:

Background & Aims: Hepatitis B virus (HBV) infection persists because the virus-specific immune response is dysfunctional. Therapeutic vaccines might be used to end immune tolerance to the virus in patients with chronic infection, but these have not been effective in patients so far. In patients with chronic HBV infection, high levels of virus antigens might prevent induction of HBV-specific immune responses. We investigated whether knocking down expression levels of HBV antigens in liver might increase the efficacy of HBV vaccines in mice.

Methods: We performed studies with male C57BL/6 mice that persistently replicate HBV (genotype D, serotype ayw)-either from a transgene or after infection with an adeno-associated virus that transferred an overlength HBV genome-and expressed HB surface antigen at levels relevant to patients. Small hairpin or small interfering (si)RNAs against the common 3'-end of all HBV transcripts were used to knock down antigen expression in mouse hepatocytes. siRNAs were chemically stabilized and conjugated to N-acetylgalactosamine to increase liver uptake. Control mice were given either entecavir or non-HBV-specific siRNAs and vaccine components. Eight to 12 weeks later, mice were immunized twice with a mixture of adjuvanted HBV S and core antigen, followed by a modified Vaccinia virus Ankara vector to induce HBV-specific B- and T-cell responses. Serum and liver samples were collected and analyzed for HBV-specific immune responses, liver damage, and viral parameters.

Results: 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 log 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 after administration of entecavir, developed polyfunctional, HBV-specific CD8 T cells, and HBV was eliminated.

Conclusions: In mice with high levels of HBV replication, knockdown of HBV antigen expression along with a therapeutic vaccination strategy, but not knockdown alone, increased numbers of effector T cells and eliminated the virus. These findings indicate that high titers of virus antigens reduce the efficacy of therapeutic vaccination. Anti-HBV siRNAs and therapeutic vaccines are each being tested in clinical trials-their combination might cure chronic HBV infection.
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http://dx.doi.org/10.1053/j.gastro.2020.01.032DOI Listing
May 2020

Key features and homing properties of NK cells in the liver are shaped by activated iNKT cells.

Sci Rep 2019 11 8;9(1):16362. Epub 2019 Nov 8.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany.

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.
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http://dx.doi.org/10.1038/s41598-019-52666-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6841958PMC
November 2019

Mucosal CD8+ T cell responses induced by an MCMV based vaccine vector confer protection against influenza challenge.

PLoS Pathog 2019 09 16;15(9):e1008036. Epub 2019 Sep 16.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.

Cytomegalovirus (CMV) is a ubiquitous β-herpesvirus that establishes life-long latent infection in a high percentage of the population worldwide. CMV induces the strongest and most durable CD8+ T cell response known in human clinical medicine. Due to its unique properties, the virus represents a promising candidate vaccine vector for the induction of persistent cellular immunity. To take advantage of this, we constructed a recombinant murine CMV (MCMV) expressing an MHC-I restricted epitope from influenza A virus (IAV) H1N1 within the immediate early 2 (ie2) gene. Only mice that were immunized intranasally (i.n.) were capable of controlling IAV infection, despite the greater potency of the intraperitoneally (i.p.) vaccination in inducing a systemic IAV-specific CD8+ T cell response. The protective capacity of the i.n. immunization was associated with its ability to induce IAV-specific tissue-resident memory CD8+ T (CD8TRM) cells in the lungs. Our data demonstrate that the protective effect exerted by the i.n. immunization was critically mediated by antigen-specific CD8+ T cells. CD8TRM cells promoted the induction of IFNγ and chemokines that facilitate the recruitment of antigen-specific CD8+ T cells to the lungs. Overall, our results showed that locally applied MCMV vectors could induce mucosal immunity at sites of entry, providing superior immune protection against respiratory infections.
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http://dx.doi.org/10.1371/journal.ppat.1008036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6763260PMC
September 2019

Neutralization of Pro-inflammatory Cytokines During Secondary Infection Post Influenza A Virus Infection.

Front Immunol 2019 14;10:1864. Epub 2019 Aug 14.

Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany.

An overt pro-inflammatory immune response is a key factor contributing to lethal pneumococcal infection in an influenza pre-infected host and represents a potential target for therapeutic intervention. However, there is a paucity of knowledge about the level of contribution of individual cytokines. Based on the predictions of our previous mathematical modeling approach, the potential benefit of IFN-γ- and/or IL-6-specific antibody-mediated cytokine neutralization was explored in C57BL/6 mice infected with the influenza A/PR/8/34 strain, which were subsequently infected with the strain TIGR4 on day 7 post influenza. While single IL-6 neutralization had no effect on respiratory bacterial clearance, single IFN-γ neutralization enhanced local bacterial clearance in the lungs. Concomitant neutralization of IFN-γ and IL-6 significantly reduced the degree of pneumonia as well as bacteremia compared to the control group, indicating a positive effect for the host during secondary bacterial infection. The results of our model-driven experimental study reveal that the predicted therapeutic value of IFN-γ and IL-6 neutralization in secondary pneumococcal infection following influenza infection is tightly dependent on the experimental protocol while at the same time paving the way toward the development of effective immune therapies.
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http://dx.doi.org/10.3389/fimmu.2019.01864DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6702285PMC
October 2020

Neutral Lipopolyplexes for In Vivo Delivery of Conventional and Replicative RNA Vaccine.

Mol Ther Nucleic Acids 2019 Sep 30;17:767-775. Epub 2019 Jul 30.

Centre de Biophysique Moléculaire, UPR4301 CNRS Rue Charles Sadron Orléans, Orléans Cedex 02, France. Electronic address:

Nucleic acid vaccination relies on injecting DNA or RNA coding antigen(s) to induce a protective immune response. RNA vaccination is being increasingly used in preclinical and clinical studies. However, few delivery systems have been reported for in vivo delivery of RNA of different sizes. Using a tripartite formulation with RNA, cationic polymer, and anionic liposomes, we were able to encapsulate RNA into neutral lipopolyplexes (LPPs). LPPs were stable in vitro and successfully delivered conventional RNA and replicative RNA to dendritic cells in cellulo. Their injection led to reporter gene expression in mice. Finally, administration of LPP-Replicon RNA (RepRNA) led to an adaptive immune response against the antigen coded by the RepRNA. Accordingly, LPPs may represent a universal formulation for RNA delivery.
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http://dx.doi.org/10.1016/j.omtn.2019.07.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6716064PMC
September 2019

Invariant NKT Cell-Mediated Modulation of ILC1s as a Tool for Mucosal Immune Intervention.

Front Immunol 2019 7;10:1849. Epub 2019 Aug 7.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.

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 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.
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http://dx.doi.org/10.3389/fimmu.2019.01849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6692890PMC
October 2020

Self-reported diabetes and herpes zoster are associated with a weak humoral response to the seasonal influenza A H1N1 vaccine antigen among the elderly.

BMC Infect Dis 2019 Jul 23;19(1):656. Epub 2019 Jul 23.

Helmholtz Centre for Infection Research, Braunschweig, Germany.

Background: The immune response to seasonal influenza vaccines decreases with advancing age. Therefore, an adjuvanted inactivated trivalent influenza vaccine (Fluad®) exists for elderly individuals. Fluad® is more immunogenic and efficacious than conventional influenza vaccines. However, the immune response varies and may still result in high frequencies of poor responders. Therefore, we aimed to a) examine the prevalence of a weak response to Fluad® and b) identify potential risk factors.

Methods: A prospective population-based study among individuals 65-80 years old was conducted in 2015/2016 in Hannover, Germany (n = 200). Hemagglutination-inhibition titers 21 days after vaccination with Fluad® served as indicator of vaccine responsiveness.

Results: The percentage of vaccinees with an inadequate vaccine response varied depending on the influenza strain: it was lowest for H3N2 (13.5%; 95% CI, 9.4-18.9%), intermediate for B strain (37.0%; 30.6-43.9%), and highest for H1N1 (49.0%; 42.2-55.9%). The risk of a weak response to the influenza A H1N1 strain was independently associated with self-reported diabetes (AOR, 4.64; 95% CI, 1.16-18.54), a history of herpes zoster (2.27; 1.01-5.10) and, to a much lesser extent, increasing age (change per year, 1.08; 0.99-1.16). In addition, herpes zoster was the only risk factor for a weak response to the H3N2 antigen (AOR, 3.12; 1.18-8.23). We found no significant association between sex, Body Mass Index, cancer, hypertension, heart attack and CMV seropositivity and a weak response to these two influenza A antigens. Despite its occurence in over one third of vaccinees, none of the variables examined proved to be risk factors for a weak response to the B antigen.

Conclusions: A considerable proportion of elderly individuals displayed a weak vaccine response to this adjuvanted seasonal influenza vaccine and further efforts are thus needed to improve immune responses to influenza vaccination among the elderly. Diabetes and herpes zoster were identified as potentially modifiable risk factors for a poor vaccine response against influenza A antigens, but the results also reveal the need for broader investigations to identify risk factors for inadequate responses to influenza B antigens.

Trial Registration: No. NCT02362919 (ClinicalTrials.gov, date of registration: 09.02.2015).
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http://dx.doi.org/10.1186/s12879-019-4214-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651912PMC
July 2019

The STING activator c-di-AMP exerts superior adjuvant properties than the formulation poly(I:C)/CpG after subcutaneous vaccination with soluble protein antigen or DEC-205-mediated antigen targeting to dendritic cells.

Vaccine 2019 08 15;37(35):4963-4974. Epub 2019 Jul 15.

Infection Immunology Group, Institute of Medical Microbiology, Infection Control and Prevention, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany; Immune Regulation Group, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. Electronic address:

Vaccination is the most efficient strategy to protect from infectious diseases and the induction of a protective immune response not only depends on the nature of the antigen, but is also influenced by the vaccination strategy and the co-administration of adjuvants. Therefore, the precise monitoring of adjuvant candidates and their immune modulatory properties is a crucial step in vaccine development. Here, one central aspect is the induction of appropriate humoral and cellular effector mechanisms. In our study we performed a direct comparison of two promising candidates in adjuvant development, the STING activator bis-(3,5)-cyclic dimeric adenosine monophosphate (c-di-AMP) and the Toll-like receptor ligand formulation poly(I:C)/CpG. These were evaluated in C57BL/6 mice using the model antigen ovalbumin (OVA) in subcutaneous vaccination with soluble protein as well as in a dendritic cell (DC) targeting approach (αDEC-OVA). Strikingly, c-di-AMP as compared to poly(I:C)/CpG resulted in significantly higher antigen-specific IgG antibody levels when used in immunization with soluble OVA as well as in antigen targeting to DC. In vaccination with soluble OVA, c-di-AMP induced a significantly stronger CTL, Th1 and IFNγ-producing CD8 memory T cell response than poly(I:C)/CpG. The response was CTL and Th1 cell dominated, a profile shared by both adjuvants. In the context of targeting OVA to DC, c-di-AMP induced significantly increased Th1 and Th2 cell responses as compared to poly(I:C)/CpG. Interestingly, the Th1 response dominated the overall T cell response only when c-di-AMP was used, indicating a distinct modulatory property of c-di-AMP when the DC targeting immunization approach was exploited. Taken together, we describe superior properties of c-di-AMP as compared to poly(I:C)/CpG in subcutaneous vaccination with soluble antigen as well as antigen targeting to DC. This indicates exceptionally effective adjuvant properties for c-di-AMP and provides compelling evidence of its potential for further adjuvant development, especially also when using DC targeting approaches.
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http://dx.doi.org/10.1016/j.vaccine.2019.07.019DOI Listing
August 2019

Novel colloidal associations of soyasaponins and lipid components (DPPC, cholesterol) as potential adjuvants for vaccines.

Vaccine 2019 08 15;37(35):4975-4986. Epub 2019 Jul 15.

Institut für Pharmazeutische Technologie, Technische Universität Braunschweig, Braunschweig, Germany; Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany. Electronic address:

Soyasaponins from soybean (Glycine max) represent promising new potent adjuvants for vaccine research because of their immunostimulating properties and weak hemolytic activity. In the present study, saponin microstructures of soyasaponins (soyasaponin Bb, soyasaponin Ab) with lipid components (cholesterol, DPPC (dipalmitoylphosphatidylcholine)) were designed by the lipid film method. In interaction studies between soyasaponins (soyasaponin Ab/Bb) and Langmuir monolayers (model membranes), composed of cholesterol and DPPC, marked interactions between soyasaponins and a pure cholesterol monolayer were observed. No interaction was detected for soyasaponins with a pure DPPC monolayer. The intercalation of soyasaponins in a mixed DPPC/cholesterol (3:1, w/w) monolayer was only observed for the monodesmosidic soyasaponin Bb whereas the second sugar chain of the bidesmosidic soyasaponin Ab impaired the access to the monolayer. Transmission electron microscopy was used for visualizing particle formation of soyasaponins and lipid components. Pseudo-binary systems (soyasaponin Ab/Bb, cholesterol) formed colloidal associations built up from ring-like subunits in the nanometer size range. In pseudo-ternary systems (soyasaponin, cholesterol, DPPC) soyasaponin Bb attacked the liposomal membrane by forming colloidal associations. Colloidal associations in pseudo-ternary systems with soyasaponin Ab, cholesterol and a phospholipid were only observed in the presence of PE (phosphatidylethanolamine) instead of DPPC. In an MTT assay with a HaCaT cell line (keratinocyte cell line) the cell viability was neither affected by the soyasaponins nor by the corresponding formulations. Both the pure soyasaponin solution and the saponin formulations may be promising adjuvant systems for the intradermal vaccine application. Furthermore, interaction studies between the model antigen ovalbumin and colloidal associations of saponins and cholesterol using MST (Microscale Thermophoresis) gave first indications of an antigen binding to colloidal associations. Ex vivo T-cell proliferation in the presence of soyasaponin Ab was confirmed.
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http://dx.doi.org/10.1016/j.vaccine.2019.07.020DOI Listing
August 2019

Systems Immunology Characterization of Novel Vaccine Formulations for Bacterins.

Front Immunol 2019 24;10:1087. Epub 2019 May 24.

Institute of Virology and Immunology, Mittelhäusern, Switzerland.

We characterized five different vaccine candidates and a commercial vaccine in terms of safety, immunogenicity and using a systems vaccinology approach, with the aim to select novel vaccine candidates against . Seven groups of six -free piglets were primo- and booster vaccinated with the different experimental bacterin formulations, the commercial vaccine Hyogen® as a positive control or PBS as a negative control. The experimental bacterin was formulated with cationic liposomes + c-di-AMP (Lipo_AMP), cationic liposomes + Toll-like receptor (TLR) 2/1, TLR7, and TLR9 ligands (TLR ligands; Lipo_TLR), micro-particles + TLR ligands (PLGA_TLR), squalene-in-water emulsion + TLR ligands (SWE_TLR), or DDA:TDB liposomes (Lipo_DDA:TDB). Lipo_DDA:TDB and Lipo_AMP were the most potent in terms of serum antibody induction, and Lipo_DDA:TDB, Lipo_AMP, and SWE_TLR significantly induced Th1 cytokine-secreting T-cells. Only PLGA_TLR appeared to induce Th17 cells, but was unable to induce serum antibodies. The transcriptomic analyses demonstrated that the induction of inflammatory and myeloid cell blood transcriptional modules (BTM) in the first 24 h after vaccination correlated well with serum antibodies, while negative correlations with the same modules were found 7 days post-vaccination. Furthermore, many cell cycle and T-cell BTM upregulated at day seven correlated positively with adaptive immune responses. When comparing the delivery of the identical TLR ligands with the three formulations, we found SWE_TLR to be more potent in the induction of an early innate immune response, while the liposomal formulation more strongly promoted late cell cycle and T-cell BTM. For the PLGA formulation we found signs of a delayed and weak perturbation of these BTM. Lipo_AMP was found to be the most potent vaccine at inducing a BTM profile similar to that correlating with adaptive immune response in this and other studies. Taken together, we identified four promising vaccine candidates able to induce -specific antibody and T-cell responses. In addition, we have adapted a systems vaccinology approach developed for human to pigs and demonstrated its capacity in identifying early immune signatures in the blood relating to adaptive immune responses. This approach represents an important step in a more rational design of efficacious vaccines for pigs.
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http://dx.doi.org/10.3389/fimmu.2019.01087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543460PMC
September 2020

The Combination Vaccine Adjuvant System Alum/c-di-AMP Results in Quantitative and Qualitative Enhanced Immune Responses Post Immunization.

Front Cell Infect Microbiol 2019 19;9:31. Epub 2019 Feb 19.

Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.

The development of new effective vaccines strongly depends on adjuvants and formulations able to stimulate not only strong humoral responses against a certain pathogen but also effector as well as memory CD4+ and CD8+ T cells (Dubensky et al., 2013). However, the majority of vaccines licensed for human use or currently under clinical investigation fail to stimulate efficient cellular responses. For example, vaccines against hepatitis B virus (HBV), human papillomavirus (HPV), diphtheria, tetanus and influenza are usually administered by intramuscular (i.m.) injection and contain aluminum salts (alum) as adjuvant. Alum has been shown to stimulate Th2 immune cells resulting in increased production of antigen-specific antibodies but to be incapable of stimulating robust Th1 or cytotoxic responses. To overcome such limitations recent research has focused on the development of adjuvant combinations (e.g., MF59, AS03 or AS04) to not only further strengthen antigen-specific immune responses but to also allow their modulation. We have shown previously that bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) constitutes a promising adjuvant candidate stimulating both effective Th1/Th2 and cytotoxic immune responses when included in mucosal or parenteral vaccine formulations. In the present work we demonstrate that c-di-AMP can be also combined with other adjuvants like alum resulting in increases in not only humoral responses but more striking also in cellular immune responses. This leads to improved vaccine efficacy against intracellular pathogens.
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http://dx.doi.org/10.3389/fcimb.2019.00031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390046PMC
November 2019

Signatures of T and B Cell Development, Functional Responses and PD-1 Upregulation After HCMV Latent Infections and Reactivations in Nod.Rag.Gamma Mice Humanized With Cord Blood CD34 Cells.

Front Immunol 2018 22;9:2734. Epub 2018 Nov 22.

Clinic of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.

Human cytomegalovirus (HCMV) latency is typically harmless but reactivation can be largely detrimental to immune compromised hosts. We modeled latency and reactivation using a traceable HCMV laboratory strain expressing the luciferase reporter gene (HCMV/GLuc) in order to interrogate the viral modulatory effects on the human adaptive immunity. Humanized mice with long-term (more than 17 weeks) steady human T and B cell immune reconstitutions were infected with HCMV/GLuc and 7 weeks later were further treated with granulocyte-colony stimulating factor (G-CSF) to induce viral reactivations. Whole body bio-luminescence imaging analyses clearly differentiated mice with latent viral infections vs. reactivations. of vigorous viral reactivations were detectable in liver, lymph nodes and salivary glands. The number of viral genome copies in various tissues increased upon reactivations and were detectable in sorted human CD14, CD169, and CD34 cells. Compared with non-infected controls, mice after infections and reactivations showed higher thymopoiesis, systemic expansion of Th, CTL, Treg, and Tfh cells and functional antiviral T cell responses. Latent infections promoted vast development of memory CD4 T cells while reactivations triggered a shift toward effector T cells expressing PD-1. Further, reactivations prompted a marked development of B cells, maturation of IgG plasma cells, and HCMV-specific antibody responses. Multivariate statistical methods were employed using T and B cell immune phenotypic profiles obtained with cells from several tissues of individual mice. The data was used to identify combinations of markers that could predict an HCMV infection vs. reactivation status. In spleen, but not in lymph nodes, higher frequencies of effector CD4 T cells expressing PD-1 were among the factors most suited to distinguish HCMV reactivations from infections. These results suggest a shift from a T cell dominated immune response during latent infections toward an exhausted T cell phenotype and active humoral immune response upon reactivations. In sum, this novel humanized model combined with advanced analyses highlights a dynamic system clearly specifying the immunological spatial signatures of HCMV latency and reactivations. These signatures can be merged as predictive biomarker clusters that can be applied in the clinical translation of new therapies for the control of HCMV reactivation.
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http://dx.doi.org/10.3389/fimmu.2018.02734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262073PMC
October 2019

Functional and immunogenic characterization of diverse HCV glycoprotein E2 variants.

J Hepatol 2019 04 13;70(4):593-602. Epub 2018 Nov 13.

Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a Joint Venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany; German Centre for Infection Research (DZIF), partner site Hannover-Braunschweig, Germany. Electronic address:

Background & Aims: Induction of cross-reactive antibodies targeting conserved epitopes of the envelope proteins E1E2 is a key requirement for an hepatitis C virus vaccine. Conserved epitopes like the viral CD81-binding site are targeted by rare broadly neutralizing antibodies. However, these viral segments are occluded by variable regions and glycans. We aimed to identify antigens exposing conserved epitopes and to characterize their immunogenicity.

Methods: We created hepatitis C virus variants with mutated glycosylation sites and/or hypervariable region 1 (HVR1). Exposure of the CD81 binding site and conserved epitopes was quantified by soluble CD81 and antibody interaction and neutralization assays. E2 or E1-E2 heterodimers with mutations causing epitope exposure were used to immunize mice. Vaccine-induced antibodies were examined and compared with patient-derived antibodies.

Results: Mutant viruses bound soluble CD81 and antibodies targeting the CD81 binding site with enhanced efficacy. Mice immunized with E2 or E1E2 heterodimers incorporating these modifications mounted strong, cross-binding, and non-interfering antibodies. E2-induced antibodies neutralized the autologous virus but they were not cross-neutralizing.

Conclusions: Viruses lacking the HVR1 and selected glycosylation sites expose the CD81 binding site and cross-neutralization antibody epitopes. Recombinant E2 proteins carrying these modifications induce strong cross-binding but not cross-neutralizing antibodies.

Lay Summary: Conserved viral epitopes can be made considerably more accessible for binding of potently neutralizing antibodies by deletion of hypervariable region 1 and selected glycosylation sites. Recombinant E2 proteins carrying these mutations are unable to elicit cross-neutralizing antibodies suggesting that exposure of conserved epitopes is not sufficient to focus antibody responses on production of cross-neutralizing antibodies.
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http://dx.doi.org/10.1016/j.jhep.2018.11.003DOI Listing
April 2019

Respiratory Carriage is Associated with Broad Phenotypic Alterations of Peripheral CD4⁺CD25⁺ T Cells and Differentially Affects Immune Responses to Secondary Non-Infectious and Infectious Stimuli in Mice.

Int J Mol Sci 2018 Sep 1;19(9). Epub 2018 Sep 1.

Infection Immunology Group, Institute of Medical Microbiology, Infection Control and Prevention, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, 39120 Magdeburg, Germany.

The respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with as the underlying model to comprehensively address effects on subsequent immune responses. Carriage was associated with the stimulation of -specific CD4⁺, CD8⁺, and CD4⁺CD25⁺Foxp3⁺ T cell responses, and broad transcriptional activation was observed in CD4⁺CD25⁺ T cells. Importantly, transfer of leukocytes from carriers to acutely infected mice, resulted in a significantly increased bacterial burden in the recipient's upper respiratory tract. In contrast, we found that respiratory carriage resulted in a significant benefit for the host in systemic infection with Adaptive responses to vaccination and influenza A virus infection, were unaffected by carriage. These data showed that there were significant immune modulatory processes triggered by carriage, that differentially affect subsequent immune responses. Therefore, our results demonstrated the complexity of immune regulation induced by respiratory bacterial carriage, which can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.
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http://dx.doi.org/10.3390/ijms19092602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6165163PMC
September 2018