RESUMO
Viral infections trigger the expression of interferons (IFNs) and interferon stimulated genes (ISGs), which are crucial to modulate an antiviral response. The human guanylate binding protein 1 (GBP1) is an ISG and exhibits antiviral activity against several viruses. In a previous study, GBP1 was described to impair replication of the hepatitis C virus (HCV). However, the impact of GBP1 on the HCV life cycle is still enigmatic. To monitor the expression and subcellular distribution of GBP1 and HCV we performed qPCR, Western blot, CLSM and STED microscopy, virus titration and reporter gene assays. In contrast to previous reports, we observed that HCV induces the expression of GBP1. Further, to induce GBP1 expression, the cells were stimulated with IFNγ. GBP1 modulation was achieved either by overexpression of GBP1-Wt or by siRNA-mediated knockdown. Silencing of GBP1 impaired the release of viral particles and resulted in intracellular HCV core accumulation, while overexpression of GBP1 favored viral replication and release. CLSM and STED analyses revealed a vesicular distribution of GBP1 in the perinuclear region. Here, it colocalizes with HCV core around lipid droplets, where it acts as assembly platform and thereby favors HCV morphogenesis and release. Collectively, our results identify an unprecedented function of GBP1 as a pro-viral factor. As such, it is essential for viral assembly and release acting through tethering factors involved in HCV morphogenesis onto the surface of lipid droplets.
Assuntos
Proteínas de Ligação ao GTP , Hepacivirus , Hepatite C , Humanos , Hepacivirus/fisiologia , Hepatite C/genética , Interferons , Replicação Viral , Proteínas de Ligação ao GTP/genéticaRESUMO
Three new series of macrocyclic active site-directed inhibitors of the Zika virus (ZIKV) NS2B-NS3 protease were synthesized. First, attempts were made to replace the basic P3 lysine residue of our previously described inhibitors with uncharged and more hydrophobic residues. This provided numerous compounds with inhibition constants between 30 and 50 nM. A stronger reduction of the inhibitory potency was observed when the P2 lysine was replaced by neutral residues, all of these inhibitors possess Ki values >1 µM. However, it is possible to replace the P2 lysine with the less basic 3-aminomethylphenylalanine, which provides a similarly potent inhibitor of the ZIKV protease (Ki = 2.69 nM). Crystal structure investigations showed that the P2 benzylamine structure forms comparable interactions with the protease as lysine. Twelve additional structures of these inhibitors in complex with the protease were determined, which explain many, but not all, SAR data obtained in this study. All individual modifications in the P2 or P3 position resulted in inhibitors with low antiviral efficacy in cell culture. Therefore, a third inhibitor series with combined modifications was synthesized; all of them contain a more hydrophobic d-cyclohexylalanine in the linker segment. At a concentration of 40 µM, two of these compounds possess similar antiviral potency as ribavirin at 100 µM. Due to their reliable crystallization in complex with the ZIKV protease, these cyclic compounds are very well suited for a rational structure-based development of improved inhibitors.
RESUMO
Zika virus (ZIKV) is a flavivirus that is mainly transmitted by Aedes mosquitos and normally causes mild symptoms. During the outbreak in the Americas in 2015, it was associated with more severe implications, like microcephaly in newborns and the Guillain-Barré syndrome. The lack of specific vaccines and cures strengthens the need for a deeper understanding of the virus life cycle and virus-host interactions. The restriction factor tetherin (THN) is an interferon-inducible cellular protein with broad antiviral properties. It is known to inhibit the release of various enveloped viruses by tethering them to each other and the cell membrane, thereby preventing their further spread. On the other hand, different viruses have developed various escape strategies against THN. Analysis of the cross-talk between ZIKV and THN revealed that, despite a strong induction of THN mRNA expression in ZIKV-infected cells, this is not reflected by an elevated protein level of THN. Contrariwise, the THN protein level is decreased due to a reduced half-life. The increased degradation of THN in ZIKV infected cells involves the endo-lysosomal system but does not depend on the early steps of autophagy. Enrichment of THN by depletion of the ESCRT-0 protein HRS diminishes ZIKV release and spread, which points out the capacity of THN to restrict ZIKV and explains the enhanced THN degradation in infected cells as an effective viral escape strategy. IMPORTANCE Although tetherin expression is strongly induced by ZIKV infection there is a reduction in the amount of tetherin protein. This is due to enhanced lysosomal degradation. However, if the tetherin level is rescued then the release of ZIKV is impaired. This shows that tetherin is a restriction factor for ZIKV, and the induction of an efficient degradation represents a viral escape strategy. To our knowledge, this is the first study that describes and characterizes tetherin as a restriction factor for the ZIKV life cycle.
Assuntos
Antígenos CD/metabolismo , Zika virus/fisiologia , Animais , Antígenos CD/genética , Fatores de Restrição Antivirais/genética , Fatores de Restrição Antivirais/metabolismo , Linhagem Celular , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Proteínas Ligadas por GPI/genética , Proteínas Ligadas por GPI/metabolismo , Meia-Vida , Humanos , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Inibidores de Proteassoma/farmacologia , RNA Mensageiro/genética , Liberação de VírusRESUMO
Zika virus (ZIKV) is a flavivirus that is well known for the epidemic in the Americas in 2015 and 2016 in which microcephaly in newborns and other neurological complications were connected to ZIKV infection. Many aspects of the ZIKV viral life cycle, including binding and entry into the host cell, are still enigmatic. Based on the observation that CHO cells lack expression of the epidermal growth factor receptor (EGFR) and are not permissive for various ZIKV strains, the relevance of EGFR for the viral life cycle was analyzed. Infection of A549 cells by ZIKV leads to a rapid internalization of EGFR that colocalizes with the endosomal marker EEA1. Moreover, infection by different ZIKV strains is associated with an activation of EGFR and the subsequent activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling cascade. However, treatment of the cells with methyl-ß-cyclodextrin (MßCD), which on the one hand leads to an activation of EGFR but on the other hand prevents EGFR internalization, impairs ZIKV infection. Specific inhibition of EGFR or of the Ras-Raf-MEK-ERK signal transduction cascade hinders ZIKV infection by inhibition of ZIKV entry. In accordance with this, knockout of EGFR expression impedes ZIKV entry. In the case of an already established infection, inhibition of EGFR or of downstream signaling does not affect viral replication. Taken together, these data demonstrate the relevance of EGFR in the early stages of ZIKV infection and identify EGFR as a target for antiviral strategies. IMPORTANCE These data deepen the knowledge about the ZIKV infection process and demonstrate the relevance of EGFR for ZIKV entry. In light of the fact that a variety of specific and efficient inhibitors of EGFR and of EGFR-dependent signaling have been developed and licensed, repurposing of these substances could be a helpful tool to prevent the spreading of ZIKV infection in an epidemic outbreak.
Assuntos
Internalização do Vírus/efeitos dos fármacos , Zika virus/metabolismo , Células A549 , Animais , Células CHO , Linhagem Celular , Chlorocebus aethiops , Cricetulus , Receptores ErbB/efeitos dos fármacos , Receptores ErbB/metabolismo , Receptores ErbB/fisiologia , Interações entre Hospedeiro e Microrganismos/fisiologia , Humanos , Estágios do Ciclo de Vida , Transdução de Sinais/efeitos dos fármacos , Células Vero , Replicação Viral/genética , Replicação Viral/fisiologia , Zika virus/patogenicidade , Infecção por Zika virus/virologia , beta-Ciclodextrinas/farmacologiaRESUMO
BACKGROUND: The mRNA vaccine BNT162b2 (Comirnaty, BioNTech/Pfizer) and the vaccine candidate CVnCoV (Curevac) each encode a stabilized spike protein of SARS-CoV2 as antigen but differ with respect to the nature of the mRNA (modified versus unmodified nucleotides) and the mRNA amount (30 µg versus 12 µg RNA). This study characterizes antisera elicited by these two vaccines in comparison to convalescent sera. METHODS: Sera from BNT162b2 vaccinated healthcare workers, and sera from participants of a phase I trial vaccinated with 2, 4, 6, 8, or 12 µg CVnCoV and convalescent sera from hospitalized patients were analyzed by ELISA, neutralization tests, surface plasmon resonance (SPR), and peptide arrays. RESULTS: BNT162b2-elicited sera and convalescent sera have a higher titer of spike-RBD-specific antibodies and neutralizing antibodies as compared to the CVnCoV-elicited sera. For all analyzed sera a reduction in binding and neutralizing antibodies was found for the lineage B.1.351 variant of concern. SPR analyses revealed that the CVnCoV-elicited sera have a lower fraction of slow-dissociating antibodies. Accordingly, the CVnCoV sera almost fail to compete with the spike-ACE2 interaction. The significance of common VOC mutations K417N, E484K, or N501Y focused on linear epitopes was analyzed using a peptide array approach. The peptide arrays showed a strong difference between convalescent sera and vaccine-elicited sera. Specifically, the linear epitope at position N501 was affected by the mutation and elucidates the escape of viral variants to antibodies against this linear epitope. CONCLUSION: These data reveal differences in titer, neutralizing capacity, and affinity of the antibodies between BNT162b2- and CVnCoV-elicited sera, which could contribute to the apparent differences in vaccine efficacy.
Assuntos
COVID-19 , SARS-CoV-2 , Anticorpos Neutralizantes , Anticorpos Antivirais , Vacina BNT162 , COVID-19/terapia , Ensaios Clínicos Fase I como Assunto , Epitopos , Humanos , Imunização Passiva , Peptídeos , RNA Mensageiro , RNA Viral , Vacinas Sintéticas , Vacinas de mRNA , Soroterapia para COVID-19RESUMO
Viral hepatitis is characterized as an acute or chronic inflammation of the liver induced by an infection with certain viruses. At present, around 325â¯million humans suffer from the chronic form of the disease worldwide. Each year, about 1.6â¯million people die as a result of viral hepatitis. The causative agents, hepatitis viruses, are subdivided into five groups of pathogens, which are denoted with the letters A to E (HAV to HEV). These differ from each other with respect to phylogeny, transmission, epidemiology, host-specificity, life cycle, structure, and distinct aspects of pathogenesis.The strictly human-pathogenic HAV, a member of the Picornaviridae family, mostly induces acute hepatitis and displays a dominant spread over the Global South. The Hepeviridae-affiliated HEV shows a similar epidemiology, yet spreads further into industrialized countries due to its zoonotic potential. Furthermore, HEV is defined by the capability of inducing chronic hepatitis. This course of disease is also found in a more pronounced manner for the globally prevalent HBV (Hepadnaviridae) and its satellite virus HDV (Kolmioviridae), which further increases their carcinogenic potential. Lastly, a worldwide distribution is similarly described for HCV (Flaviviridae), which displays a high risk of chronifications and therefore a highly increased carcinogenic potential.The aforementioned pathogens differ with respect to their properties and life cycles. Thus, a differentiated look on epidemiology, diagnostic procedures, and disease prevention is required. Despite the presence of therapies, in some cases even a vaccine, there is an urgent need for advances in research on these aspects, especially for poverty-related pathogens.
Assuntos
Vírus da Hepatite E , Hepatite Viral Humana , Vírus , Alemanha , Vírus de Hepatite , Humanos , PrevalênciaRESUMO
Worldwide, the hepatitis B and hepatitis C viruses (HBV, HCV) are the most relevant causative viral agents of a chronic hepatitis (inflammation of the liver). At present, more than 250 million people suffer from a chronic HBV infection globally, resulting in 0.8 million deaths per year. A chronic HCV infection accounts for about 70 million cases worldwide, leading to a death toll of about 1 million per year. An approved vaccine is only available against an HBV infection. Both HBV and HCV infections result in a highly increased risk of developing liver fibrosis, cirrhosis, and a hepatocellular carcinoma (HCC).This review aims to describe mechanisms of the HBV- and HCV-associated pathogenesis. The focus is on the interplay between a chronic infection with intracellular signaling transduction, metabolic pathways with an emphasis on lipid metabolism, the establishment of liver fibrosis and cirrhosis during a chronic infection, and the mechanisms of the onset of a virally induced HCC.Despite there being great advances in the characterization of viral life cycles and the development of robust antiviral strategies, significant hurdles persist: gaining a better understanding of the mechanisms that drive virus-associated pathogenesis as well as increasing insights regarding different viral genotypes having impacts on alternate pathogeneses.
Assuntos
Carcinoma Hepatocelular , Hepatite B Crônica , Hepatite B , Hepatite C , Neoplasias Hepáticas , Carcinogênese , Carcinoma Hepatocelular/epidemiologia , Alemanha , Hepatite B Crônica/epidemiologia , Humanos , Neoplasias Hepáticas/epidemiologiaRESUMO
With respect to their genome and their structure, the human hepatitis B virus (HBV) and hepatitis C virus (HCV) are complete different viruses. However, both viruses can cause an acute and chronic infection of the liver that is associated with liver inflammation (hepatitis). For both viruses chronic infection can lead to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Reactive oxygen species (ROS) play a central role in a variety of chronic inflammatory diseases. In light of this, this review summarizes the impact of both viruses on ROS-generating and ROS-inactivating mechanisms. The focus is on the effect of both viruses on the transcription factor Nrf2 (nuclear factor erythroid 2 (NF-E2)-related factor 2). By binding to its target sequence, the antioxidant response element (ARE), Nrf2 triggers the expression of a variety of cytoprotective genes including ROS-detoxifying enzymes. The review summarizes the literature about the pathways for the modulation of Nrf2 that are deregulated by HBV and HCV and describes the impact of Nrf2 deregulation on the viral life cycle of the respective viruses and the virus-associated pathogenesis.
Assuntos
Hepacivirus , Vírus da Hepatite B , Hepatite B/metabolismo , Hepatite C/metabolismo , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Transdução de Sinais , Replicação Viral/fisiologia , Animais , Hepacivirus/patogenicidade , Hepacivirus/fisiologia , Hepatite B/patologia , Vírus da Hepatite B/patogenicidade , Vírus da Hepatite B/fisiologia , Hepatite C/patologia , HumanosRESUMO
BACKGROUND: A peculiar feature of the hepatitis E virus (HEV) is its reliance on the exosomal route for viral release. Genomic replication is mediated via the viral polyprotein pORF1, yet little is known about its subcellular localization. METHODS: Subcellular localization of pORF1 and its subdomains, generated and cloned based on a structural prediciton of the viral replicase, was analyzed via confocal laser scanning microscopy. Exosomes released from cells were isolated via ultracentrifugation and analyzed by isopycnic density gradient centrifugation. This was followed by fluorimetry or Western blot analyses or reverse transcriptase-polymerase chain reaction to analyze separated particles in more detail. RESULTS: We found pORF1 to be accumulating within the endosomal system, most dominantly to multivesicular bodies (MVBs). Expression of the polyprotein's 7 subdomains revealed that the papain-like cysteine-protease (PCP) is the only domain localizing like the full-length protein. A PCP-deficient pORF1 mutant lost its association to MVBs. Strikingly, both pORF1 and PCP can be released via exosomes. Similarly, genomic RNA still is released via exosomes in the absence of pORF2/3. CONCLUSIONS: Taken together, we found that pORF1 localizes to MVBs in a PCP-dependent manner, which is followed by exosomal release. This reveals new aspects of HEV life cycle, because replication and release could be coupled at the endosomal interface. In addition, this may mediate capsid-independent spread or may facilitate the spread of viral infection, because genomes entering the cell during de novo infection readily encounter exosomally transferred pORF1.
Assuntos
Vírus da Hepatite E , Corpos Multivesiculares/metabolismo , Proteínas/metabolismo , Poliproteínas/metabolismo , Peptídeo Hidrolases/metabolismoRESUMO
The flavivirus genus includes human pathogenic viruses such as Dengue (DENV), West Nile (WNV) and Zika virus (ZIKV) posing a global health threat due to limited treatment options. Host ion channels are crucial for various viral life cycle stages, but their potential as targets for antivirals is often not fully realized due to the lack of selective modulators. Here, we observe that treatment with ML2-SA1, an agonist for the human endolysosomal cation channel TRPML2, impairs ZIKV replication. Upon ML2-SA1 treatment, levels of intracellular genomes and number of released virus particles of two different ZIKV isolates were significantly reduced and cells displayed enlarged vesicular structures and multivesicular bodies with ZIKV envelope protein accumulation. However, no increased ZIKV degradation in lysosomal compartments was observed. Rather, the antiviral effect of ML2-SA1 seemed to manifest by the compound's negative impact on genome replication. Moreover, ML2-SA1 treatment also led to intracellular cholesterol accumulation. ZIKV and many other viruses including the Orthohepevirus Hepatitis E virus (HEV) rely on the endolysosomal system and are affected by intracellular cholesterol levels to complete their life cycle. Since we observed that ML2-SA1 also negatively impacted HEV infections in vitro, this compound may harbor a broader antiviral potential through perturbing the intracellular cholesterol distribution. Besides indicating that TRPML2 may be a promising target for combatting viral infections, we uncover a tentative connection between this protein and cholesterol distribution within the context of infectious diseases.
Assuntos
Antivirais , Canais de Potencial de Receptor Transitório , Replicação Viral , Infecção por Zika virus , Zika virus , Zika virus/efeitos dos fármacos , Zika virus/fisiologia , Replicação Viral/efeitos dos fármacos , Humanos , Antivirais/farmacologia , Canais de Potencial de Receptor Transitório/agonistas , Canais de Potencial de Receptor Transitório/metabolismo , Infecção por Zika virus/virologia , Infecção por Zika virus/tratamento farmacológico , Chlorocebus aethiops , Animais , Células Vero , Colesterol/metabolismo , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Linhagem Celular , Células HEK293 , Ftalimidas , QuinolinasRESUMO
Zoonoses such as ZIKV and SARS-CoV-2 pose a severe risk to global health. There is urgent need for broad antiviral strategies based on host-targets filling gaps between pathogen emergence and availability of therapeutic or preventive strategies. Significant reduction of pathogen titers decreases spread of infections and thereby ensures health systems not being overloaded and public life to continue. Based on previously observed interference with FGFR1/2-signaling dependent impact on interferon stimulated gene (ISG)-expression, we identified Pim kinases as promising druggable cellular target. We therefore focused on analyzing the potential of pan-Pim kinase inhibition to trigger a broad antiviral response. The pan-Pim kinase inhibitor AZD1208 exerted an extraordinarily high antiviral effect against various ZIKV isolates, SARS-CoV-2 and HBV. This was reflected by strong reduction in viral RNA, proteins and released infectious particles. Especially in case of SARS-CoV-2, AZD1208 led to a complete removal of viral traces in cells. Kinome-analysis revealed vast changes in kinase landscape upon AZD1208 treatment, especially for inflammation and the PI3K/Akt-pathway. For ZIKV, a clear correlation between antiviral effect and increase in ISG-expression was observed. Based on a cell culture model with impaired ISG-induction, activation of the PI3K-Akt-mTOR axis, leading to major changes in the endolysosomal equilibrium, was identified as second pillar of the antiviral effect triggered by AZD1208-dependent Pim kinase inhibition, also against HBV. We identified Pim-kinases as cellular target for a broad antiviral activity. The antiviral effect exerted by inhibition of Pim kinases is based on at least two pillars: innate immunity and modulation of the endolysosomal system.
Assuntos
Antivirais , Imunidade Inata , Proteínas Proto-Oncogênicas c-akt , Proteínas Proto-Oncogênicas c-pim-1 , SARS-CoV-2 , Transdução de Sinais , Serina-Treonina Quinases TOR , Humanos , Imunidade Inata/efeitos dos fármacos , Antivirais/farmacologia , Serina-Treonina Quinases TOR/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/imunologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Zika virus/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Animais , Vírus da Hepatite B/efeitos dos fármacos , Endossomos/efeitos dos fármacos , Endossomos/metabolismo , Linhagem Celular , COVID-19/imunologia , COVID-19/virologia , Tratamento Farmacológico da COVID-19 , Replicação Viral/efeitos dos fármacos , Compostos de Bifenilo , TiazolidinasRESUMO
Human pathogenic bacteria circulating in the bloodstream need to find a way to interact with endothelial cells (ECs) lining the blood vessels to infect and colonise the host. The extracellular matrix (ECM) of ECs might represent an attractive initial target for bacterial interaction, as many bacterial adhesins have reported affinities to ECM proteins, in particular to fibronectin (Fn). Here, we analysed the general role of EC-expressed Fn for bacterial adhesion. For this, we evaluated the expression levels of ECM coding genes in different ECs, revealing that Fn is the highest expressed gene and thereby, it is highly abundant in the ECM environment of ECs. The role of Fn as a mediator in bacterial cell-host adhesion was evaluated in adhesion assays of Acinetobacter baumannii, Bartonella henselae, Borrelia burgdorferi, and Staphylococcus aureus to ECs. The assays demonstrated that bacteria colocalised with Fn fibres, as observed by confocal laser scanning microscopy. Fn removal from the ECM environment (FN1 knockout ECs) diminished bacterial adherence to ECs in both static and dynamic adhesion assays to varying extents, as evaluated via absolute quantification using qPCR. Interactions between adhesins and Fn might represent the crucial step for the adhesion of human-pathogenic Gram-negative and Gram-positive bacteria targeting the ECs as a niche of infection.
Assuntos
Bartonella henselae , Fibronectinas , Humanos , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Aderência Bacteriana , Bartonella henselae/genética , Bartonella henselae/metabolismo , Células Endoteliais/microbiologia , Fibronectinas/metabolismoRESUMO
Adhesion to host cells is the first and most crucial step in infections with pathogenic Gram-negative bacteria and is often mediated by trimeric autotransporter adhesins (TAAs). Bartonella henselae targets the extracellular matrix glycoprotein fibronectin (Fn) via the Bartonella adhesin A (BadA) attaching the bacteria to the host cell. The TAA BadA is characterized by a highly repetitive passenger domain consisting of 30 neck/stalk domains with various degrees of similarity. To elucidate the motif sequences mediating Fn binding, we generated 10 modified BadA constructs and verified their expression via Western blotting, confocal laser scanning, and electron microscopy. We analyzed their ability to bind human plasma Fn using quantitative whole-cell enzyme-linked immunosorbent assays (ELISAs) and fluorescence microscopy. Polyclonal antibodies targeting a 15-mer amino acid motif sequence proved to reduce Fn binding. We suggest that BadA adheres to Fn in a cumulative effort with quick saturation primarily via unpaired ß-strands appearing in motifs repeatedly present throughout the neck/stalk region. In addition, we demonstrated that the length of truncated BadA constructs correlates with the immunoreactivity of human patient sera. The identification of BadA-Fn binding regions will support the development of new "antiadhesive" compounds inhibiting the initial adherence of B. henselae and other TAA-expressing pathogens to host cells. IMPORTANCE Trimeric autotransporter adhesins (TAAs) are important virulence factors and are widely present in various pathogenic Gram-negative bacteria. TAA-expressing bacteria cause a wide spectrum of human diseases, such as cat scratch disease (Bartonella henselae), enterocolitis (Yersinia enterocolitica), meningitis (Neisseria meningitis), and bloodstream infections (multidrug-resistant Acinetobacter baumannii). TAA-targeted antiadhesive strategies (against, e.g., Bartonella adhesin A [BadA], Yersinia adhesin A [YadA], Neisseria adhesin A [NadA], and Acinetobacter trimeric autotransporter [Ata]) might represent a universal strategy to counteract such bacterial infections. BadA is one of the best characterized TAAs, and because of its high number of (sub)domains, it serves as an attractive adhesin to study the domain-function relationship of TAAs in the infection process. The identification of common binding motifs between TAAs (here, BadA) and their major binding partner (here, fibronectin) provides a basis toward the design of novel "antiadhesive" compounds preventing the initial adherence of Gram-negative bacteria in infections.
Assuntos
Bartonella henselae , Bartonella , Humanos , Bartonella henselae/genética , Bartonella henselae/metabolismo , Fibronectinas/metabolismo , Sistemas de Secreção Tipo V/metabolismo , Aderência Bacteriana , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Fatores de Virulência/metabolismoRESUMO
Zika virus (ZIKV) is a human pathogenic arbovirus. So far, neither a specific treatment nor a vaccination against ZIKV infections has been approved. Starting from our previously described lead structure, a series of 29 new macrocyclic inhibitors of the Zika virus protease containing different linker motifs have been synthesized. By selecting hydrophobic d-amino acids as part of the linker, numerous inhibitors with Ki values < 5 nM were obtained. For 12 inhibitors, crystal structures in complex with the ZIKV protease up to 1.30 Å resolution were determined, which contribute to the understanding of the observed structure-activity relationship (SAR). In immunofluorescence assays, an antiviral effect was observed for compound 26 containing a d-homocyclohexylalanine residue in its linker segment. Due to its excellent selectivity profile and low cytotoxicity, this inhibitor scaffold could be a suitable starting point for the development of peptidic drugs against the Zika virus and related flaviviruses.
Assuntos
Infecção por Zika virus , Zika virus , Antivirais/química , Antivirais/farmacologia , Humanos , Peptídeo Hidrolases/metabolismo , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Proteínas não Estruturais Virais/antagonistas & inibidores , Zika virus/efeitos dos fármacos , Zika virus/enzimologia , Infecção por Zika virus/tratamento farmacológicoRESUMO
In light of an increasing number of vaccinated and convalescent individuals, there is a major need for the development of robust methods for the quantification of neutralizing antibodies; although, a defined correlate of protection is still missing. Sera from hospitalized COVID-19 patients suffering or not suffering from acute respiratory distress syndrome (ARDS) were comparatively analyzed by plaque reduction neutralization test (PRNT) and pseudotype-based neutralization assays to quantify their neutralizing capacity. The two neutralization assays showed comparable data. In case of the non-ARDS sera, there was a distinct correlation between the data from the neutralization assays on the one hand, and enzyme-linked immune sorbent assay (ELISA), as well as biophysical analyses, on the other hand. As such, surface plasmon resonance (SPR)-based assays for quantification of binding antibodies or analysis of the stability of the antigen-antibody interaction and inhibition of syncytium formation, determined by cell fusion assays, were performed. In the case of ARDS sera, which are characterized by a significantly higher fraction of RBD-binding IgA antibodies, there is a clear correlation between the neutralization assays and the ELISA data. In contrast to this, a less clear correlation between the biophysical analyses on the one hand and ELISAs and neutralization assays on the other hand was observed, which might be explained by the heterogeneity of the antibodies. To conclude, for less complex immune sera-as in cases of non-ARDS sera-combinations of titer quantification by ELISA with inhibition of syncytium formation, SPR-based analysis of antibody binding, determination of the stability of the antigen-antibody complex, and competition of the RBD-ACE2 binding represent alternatives to the classic PRNT for analysis of the neutralizing potential of SARS-CoV-2-specific sera, without the requirement for a BSL3 facility.
Assuntos
Anticorpos Antivirais/sangue , Convalescença , Soros Imunes/análise , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/sangue , Glicoproteína da Espícula de Coronavírus/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Neutralizantes/imunologia , COVID-19/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Soros Imunes/imunologia , Imunidade Humoral , Masculino , Pessoa de Meia-Idade , Testes de NeutralizaçãoRESUMO
After binding of its ligand transferrin, the transferrin receptor (TfR) is internalized via early endosomes. Ligand and receptor can be recycled. α-Taxilin was identified as an essential factor for TfR recycling. Apart from its role for iron uptake, TfR is a coreceptor for hepatitis C virus (HCV) infection. In HCV-replicating cells, the amount of a-taxilin is decreased. This study aims to investigate the effect of decreased α-taxilin levels in HCV-replicating cells on recycling of TfR, its amount on the cell surface, on iron uptake, and the impact of a disturbed TfR recycling on HCV superinfection exclusion. TfR amount and localization were determined by CLSM and surface biotinylation. α-taxilin expression was modulated by CRISPR-Cas9 knockout, siRNA, and stable or transient overexpression. For analysis of HCV superinfection fluorophor-tagged reporter viruses were used. The amount of α-taxilin is decreased in HCV-infected cells. In accordance to this, the protein amount of TfR is significant lower in HCV-positve cells as compared to the control, while TfR expression is not affected. Due to the impaired recycling, internalized TfR is degraded by the endosomal/lysosomal system. The significant lower number of TfR molecules on the cell surface is reflected by reduced transferrin binding/internalization and strong reduction of intracellular iron level. Overexpression of α-taxilin in HCV-replicating cells rescues TfR recycling, augments TfR on the cell surface, and restores transferrin binding. The block of superinfection in HCV-replicating cells could be overcome by overexpression of α-taxilin. Taken together, the diminished level of α-taxilin in HCV-replicating cells prevents recycling of TfR leading to decreased transferrin binding and iron uptake. Disappearance of TfR from the cell surface could be a factor contributing to the exclusion of superinfection by HCV.
RESUMO
The N-terminus of the hepatitis B virus (HBV) large surface protein (LHB) differs with respect to genotypes. Compared to the amino terminus of genotype (Gt)D, in GtA, GtB and GtC, an additional identical 11 amino acids (aa) are found, while GtE and GtG share another similar 10 aa. Variants of GtB and GtC affecting this N-terminal part are associated with hepatoma formation. Deletion of these amino-terminal 11 aa in GtA reduces the amount of LHBs and changes subcellular accumulation (GtA-like pattern) to a dispersed distribution (GtD-like pattern). Vice versa, the fusion of the GtA-derived N-terminal 11 aa to GtD causes a GtA-like phenotype. However, insertion of the corresponding GtE-derived 10 aa to GtD has no effect. Deletion of these 11aa decreases filament size while neither the number of released viral genomes nor virion size and infectivity are affected. A negative regulatory element (aa 2-8) and a dominant positive regulatory element (aa 9-11) affecting the amount of LHBs were identified. The fusion of this motif to eGFP revealed that the effect on protein amount and subcellular distribution is not restricted to LHBs. These data identify a novel region in the N-terminus of LHBs affecting the amount and subcellular distribution of LHBs and identify release-promoting and -inhibiting aa residues within this motive.
Assuntos
Genótipo , Antígenos de Superfície da Hepatite B/genética , Vírus da Hepatite B/genética , Hepatite B Crônica/sangue , Morfogênese , Domínios Proteicos/genética , Precursores de Proteínas/genética , Proteínas do Envelope Viral/química , Vírion/crescimento & desenvolvimento , Adulto , Negro ou Afro-Americano/genética , Povo Asiático/genética , Linhagem Celular Tumoral , DNA Viral/sangue , Feminino , Hepatite B Crônica/etnologia , Hepatite B Crônica/virologia , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas do Envelope Viral/metabolismo , População Branca/genéticaRESUMO
Zika virus (ZIKV) is a mosquito-borne virus, which can cause brain abnormalities in newborns, including microcephaly. MicroRNAs (miRNAs) are small non-coding RNAs, which post- transcriptionally regulate gene expression. They are involved in various processes including neurological development and host responses to viral infection, but their potential role in ZIKV pathogenesis remains poorly understood. MiRNAs can be incorporated into extracellular vesicles (EVs) and mediate cell-to-cell communication. While it is well known that in viral infections EVs carrying miRNAs can play a crucial role in disease pathogenesis, ZIKV effects on EV-delivered miRNAs and their contribution to ZIKV pathogenesis have not been elucidated. In the present study, we profiled intracellular and EV-derived miRNAs by next generation sequencing and analyzed the host mRNA transcriptome of neural stem cells during infection with ZIKV Uganda and French Polynesia strains. We identified numerous miRNAs, including miR-4792, which were dysregulated at the intracellular level and had altered levels in EVs during ZIKV infection. Integrated analyses of differentially expressed genes and miRNAs showed that ZIKV infection had an impact on processes associated with neurodevelopment and oxidative stress. Our results provide insights into the roles of intracellular and EV-associated host miRNAs in ZIKV pathogenesis.
Assuntos
Vesículas Extracelulares/virologia , Interações entre Hospedeiro e Microrganismos/genética , MicroRNAs/genética , Células-Tronco Neurais/virologia , Transcriptoma , Adulto , Técnicas de Cultura de Células , Células Cultivadas , Feminino , Perfilação da Expressão Gênica , Humanos , Replicação Viral , Zika virus/genética , Zika virus/patogenicidade , Zika virus/fisiologiaRESUMO
Fibroblast growth factors (FGFs) play key roles in the pathogenesis of different human diseases, but the cross-talk between FGFs and other cytokines remains largely unexplored. We identified an unexpected antagonistic effect of FGFs on the interferon (IFN) signaling pathway. Genetic or pharmacological inhibition of FGF receptor signaling in keratinocytes promoted the expression of interferon-stimulated genes (ISG) and proteins in vitro and in vivo. Conversely, FGF7 or FGF10 treatment of keratinocytes suppressed ISG expression under homeostatic conditions and in response to IFN or poly(I:C) treatment. FGF-mediated ISG suppression was independent of IFN receptors, occurred at the transcriptional level, and required FGF receptor kinase and proteasomal activity. It is not restricted to keratinocytes and functionally relevant, since FGFs promoted the replication of herpes simplex virus I (HSV-1), lymphocytic choriomeningitis virus, and Zika virus. Most importantly, inhibition of FGFR signaling blocked HSV-1 replication in cultured human keratinocytes and in mice. These results suggest the use of FGFR kinase inhibitors for the treatment of viral infections.
Assuntos
Infecção por Zika virus , Zika virus , Animais , Fatores de Crescimento de Fibroblastos , Humanos , Interferons , Camundongos , Receptores de Fatores de Crescimento de Fibroblastos , Transdução de Sinais , Replicação ViralRESUMO
Zika virus (ZIKV) is a highly transmissive virus that belongs to the Flaviviridae family, which comprises several other pathogens that threaten human health. This re-emerging virus gained attention during the outbreak in Brazil in 2016, where a considerable number of microcephaly cases in newborns was associated with ZIKV infection during pregnancy. Lacking a preventive vaccine or antiviral drugs, efforts have been made to better understand the viral life cycle. In light of this, the relevance of the endosomal-lysosomal compartment for the ZIKV life cycle was investigated. A549 and SH-SY5Y cells were infected with either the African strain (associated with mild symptoms) or the French Polynesia strain (associated with neurological complications). For both strains, the V-ATPase inhibitor, bafilomycin A1, efficiently inhibited ZIKV entry and prevented the spread of the infection by interfering with viral maturation. Additionally, affecting cholesterol metabolism and transport with the drug U18666A, which inactivates late endosomes and lysosomes, impairs the viral life cycle. The data presented show a clear antiviral effect of two compounds that target the same compartments in different ways. This highlights the relevance of the endosomal-lysosomal compartment for the viral life cycle that should be considered as a target for antivirals.