Electron microscopy stands as a cornerstone in unraveling the intricate dynamics of viral infections, with its high-resolution capabilities offering invaluable insights into the interactions between viruses and the infected cells. Here, we present a comprehensive methodology designed to explore the three-dimensional interactions specifically between tick-borne encephalitis virus (TBEV) and host cells. This approach allows to study all stages of viral lifecycle, including replication, budding, maturation, and host cell defense mechanisms. The methodology encompasses a range of techniques, commencing with sample preparation using high-pressure freezing, followed by freeze substitution, epoxy embedding, and ultrathin sectioning. Subsequently, we employ electron tomography in conjunction with image processing and analysis techniques to unravel the intricate nuances of TBEV-host cell interactions.

• Keywords
• Electron tomography, Tick-borne encephalitis virus, Transmission electron microscopy,
• MeSH
• Cell Line MeSH
• Host-Pathogen Interactions * MeSH
• Encephalitis, Tick-Borne * virology   MeSH
• Humans MeSH
• Freeze Substitution MeSH
• Virus Replication MeSH
• Electron Microscope Tomography * methods   MeSH
• Encephalitis Viruses, Tick-Borne * physiology   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Tick-borne encephalitis (TBE) virus (TBEV) is transmitted to humans via tick bites. Infection is benign in >90% of the cases but can cause mild (<5%), moderate (<4%), or severe (<1%) encephalitis. We show here that ∼10% of patients hospitalized for severe TBE in cohorts from Austria, Czech Republic, and France carry auto-Abs neutralizing IFN-α2, -β, and/or -ω at the onset of disease, contrasting with only ∼1% of patients with moderate and mild TBE. These auto-Abs were found in two of eight patients who died and none of 13 with silent infection. The odds ratios (OR) for severe TBE in individuals with these auto-Abs relative to those without them in the general population were 4.9 (95% CI: 1.5-15.9, P < 0.0001) for the neutralization of only 100 pg/ml IFN-α2 and/or -ω, and 20.8 (95% CI: 4.5-97.4, P < 0.0001) for the neutralization of 10 ng/ml IFN-α2 and -ω. Auto-Abs neutralizing type I IFNs accounted for ∼10% of severe TBE cases in these three European cohorts.

• MeSH
• Autoantibodies * immunology   MeSH
• Adult MeSH
• Interferon Type I * immunology   MeSH
• Encephalitis, Tick-Borne * immunology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Antibodies, Neutralizing * immunology   MeSH
• Aged MeSH
• Encephalitis Viruses, Tick-Borne immunology   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Austria epidemiology   MeSH
• Names of Substances
• Autoantibodies * MeSH
• Interferon Type I * MeSH
• Antibodies, Neutralizing * MeSH

Tick-borne encephalitis virus (TBEV) targets the central nervous system (CNS), leading to potentially severe neurological complications. The neurovascular unit plays a fundamental role in the CNS and in the neuroinvasion of TBEV. However, the role of human brain pericytes, a key component of the neurovascular unit, during TBEV infection has not yet been elucidated. In this study, TBEV infection of the primary human brain perivascular pericytes was investigated with highly virulent Hypr strain and mildly virulent Neudoerfl strain. We used Luminex assay to measure cytokines/chemokines and growth factors. Both viral strains showed comparable replication kinetics, peaking at 3 days post infection (dpi). Intracellular viral RNA copies peaked at 6 dpi for Hypr and 3 dpi for Neudoerfl cultures. According to immunofluorescence staining, only small proportion of pericytes were infected (3% for Hypr and 2% for Neudoerfl), and no cytopathic effect was observed in the infected cells. In cell culture supernatants, IL-6 production was detected at 3 dpi, together with slight increases in IL-15 and IL-4, but IP-10, RANTES and MCP-1 were the main chemokines released after TBEV infection. These chemokines play key roles in both immune defense and immunopathology during TBE. This study suggests that pericytes are an important source of these signaling molecules during TBEV infection in the brain.

• Keywords
• CCL5, CXCL10, chemokine, flavivirus, human pericytes, infection, inflammation, tick-borne encephalitis virus,
• MeSH
• Chemokine CCL5 * metabolism   MeSH
• Chemokine CXCL10 * metabolism   MeSH
• Cytokines metabolism   MeSH
• Encephalitis, Tick-Borne * virology   metabolism   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Brain * virology   metabolism   pathology   MeSH
• Pericytes * virology   metabolism   MeSH
• Virus Replication MeSH
• Encephalitis Viruses, Tick-Borne * physiology   pathogenicity   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• CCL5 protein, human MeSH Browser
• Chemokine CCL5 * MeSH
• Chemokine CXCL10 * MeSH
• CXCL10 protein, human MeSH Browser
• Cytokines MeSH

Matrix metalloproteinases (MMPs) play an important role in central nervous system infections. We analysed the levels of 8 different MMPs in the cerebrospinal fluid (CSF) of 89 adult patients infected with tick-borne encephalitis (TBE) virus and compared them with the levels in a control group. MMP-9 was the only MMP that showed significantly increased CSF levels in TBE patients. Serum MMP-9 levels were subsequently measured in 101 adult TBE patients at various time points during the neurological phase of TBE and at follow-up. In addition, serum MMP-9 was analysed in 37 paediatric TBE patients. Compared with control levels, both paediatric and adult TBE patients had significantly elevated serum MMP-9 levels. In most adult patients, serum MMP-9 levels peaked at hospital admission, with higher serum MMP-9 levels observed in patients with encephalitis than in patients with meningitis. Elevated serum MMP-9 levels were observed throughout hospitalisation but decreased to normal levels at follow-up. Serum MMP-9 levels correlated with clinical course, especially in patients heterozygous for the single-nucleotide polymorphism rs17576 (A/G; Gln279Arg) in the MMP9 gene. The results highlight the importance of MMP-9 in the pathogenesis of TBE and suggest that serum MMP-9 may serve as a promising bioindicator of TBE in both paediatric and adult TBE patients.

• Keywords
• Cerebrospinal fluid, Matrix matalloproteinase, Neuroinfection, Tick-borne encephalitis,
• MeSH
• Biomarkers MeSH
• Child MeSH
• Adult MeSH
• Polymorphism, Single Nucleotide MeSH
• Encephalitis, Tick-Borne * diagnosis   cerebrospinal fluid   MeSH
• Humans MeSH
• Matrix Metalloproteinase 9 genetics   MeSH
• Encephalitis Viruses, Tick-Borne * genetics   MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• Matrix Metalloproteinase 9 MeSH
• MMP9 protein, human MeSH Browser

Tick-borne encephalitis virus (TBEV), the most medically relevant tick-transmitted flavivirus in Eurasia, targets the host central nervous system and frequently causes severe encephalitis. The severity of TBEV-induced neuropathogenesis is highly cell-type specific and the exact mechanism responsible for such differences has not been fully described yet. Thus, we performed a comprehensive analysis of alterations in host poly-(A)/miRNA/lncRNA expression upon TBEV infection in vitro in human primary neurons (high cytopathic effect) and astrocytes (low cytopathic effect). Infection with severe but not mild TBEV strain resulted in a high neuronal death rate. In comparison, infection with either of TBEV strains in human astrocytes did not. Differential expression and splicing analyses with an in silico prediction of miRNA/mRNA/lncRNA/vd-sRNA networks found significant changes in inflammatory and immune response pathways, nervous system development and regulation of mitosis in TBEV Hypr-infected neurons. Candidate mechanisms responsible for the aforementioned phenomena include specific regulation of host mRNA levels via differentially expressed miRNAs/lncRNAs or vd-sRNAs mimicking endogenous miRNAs and virus-driven modulation of host pre-mRNA splicing. We suggest that these factors are responsible for the observed differences in the virulence manifestation of both TBEV strains in different cell lines. This work brings the first complex overview of alterations in the transcriptome of human astrocytes and neurons during the infection by two TBEV strains of different virulence. The resulting data could serve as a starting point for further studies dealing with the mechanism of TBEV-host interactions and the related processes of TBEV pathogenesis.

• Keywords
• A3SS, alternative 3′ splice site, A5SS, alternative 5′ splice site, ACACA, Acetyl-CoA Carboxylase Alpha, AKR1C2, Aldo-Keto Reductase Family 1 Member C2, ANKS1A, Ankyrin Repeat And Sterile Alpha Motif Domain Containing 1A, ANOS1, Anosmin 1, AOX1, Aldehyde Oxidase 1, APOBEC3G, Apolipoprotein B MRNA Editing Enzyme Catalytic Subunit 3G, APOL1/6, Apolipoprotein L1/6, ARID2, AT-Rich Interaction Domain 2, AUTS2, Activator Of Transcription And Developmental Regulator AUTS2, Alternative splicing, Astrocytes, BCL11B, BAF Chromatin Remodeling Complex Subunit BCL11B, BCL9L, BCL9 Transcription Coactivator-like, BDKRB2, Bradykinin Receptor B2, BDNF, Brain Derived Neurotrophic Factor, BEND3, BEN Domain Containing 3, BSA, bovine serum albumin, BST2, Bone Marrow Stromal Cell Antigen 2, CALB1, Calbindin 1, CAMK2A, Calcium/Calmodulin Dependent Protein Kinase II Alpha, CD, complement determinant, CDKN1C, Cyclin Dependent Kinase Inhibitor 1C, CFAP61, Cilia And Flagella Associated Protein 61, CHRNA3, Cholinergic Receptor Nicotinic Alpha 3 Subunit, CHRNB4, Cholinergic Receptor Nicotinic Beta 4 Subunit, CLIC5, Chloride Intracellular Channel 5, CMPK2, Cytidine/Uridine Monophosphate Kinase 2, CNS, central nervous system, CNTN2, Contactin 2, CREG2, Cellular Repressor Of E1A Stimulated Genes 2, CXADR, Coxsackievirus B-Adenovirus Receptor, CYYR1, Cysteine And Tyrosine Rich 1, DACH1, Dachshund Family Transcription Factor 1, DAPI, diamidino-2-phenylindole, DCC, Netrin 1 Receptor, DCX, Doublecortin, DDX60, DExD/H-Box Helicase 60, DDX60L, DExD/H-Box 60 Like, DE, differentially expressed, DENV, Dengue virus, DIRAS2, DIRAS Family GTPase 2, DLX1/5/6, Distal-Less Homeobox 1/5/6, DNMT3B, DNA Methyltransferase 3 Beta, DPYSL2, Dihydropyrimidinase Like 2, EBF1, EBF Transcription Factor 1, EGF, Epidermal Growth Factor, ELAVL2/4, ELAV Like RNA Binding Protein 2/4, EPHB1, EPH Receptor B1, EPSTI1, Epithelial Stromal Interaction 1, ERBB4, Erb-B2 Receptor Tyrosine Kinase 4, ES, exon skipping, ESRRG, Estrogen Related Receptor Gamma, FGFb, Fibroblast Growth Factor 2, FPKM, Fragments Per Kilobase of transcript per Million mapped reads, FUT9, Fucosyltransferase 9, G2E3, G2/M−Phase Specific E3 Ubiquitin Protein Ligase, GABRG2, Gamma-Aminobutyric Acid Type A Receptor Subunit Gamma 2, GAPDH, Glyceraldehyde-3-Phosphate Dehydrogenase, GAS2L3, Growth Arrest Specific 2 Like 3, GAS7, Growth Arrest Specific 7, GATAD2B, GATA Zinc Finger Domain Containing 2B, GFAP, Glial Fibrillary Acidic Protein, GIPC2, GIPC PDZ Domain Containing Family Member 2, GLRA2, Glycine Receptor Alpha 2, GNG2, G Protein Subunit Gamma 2, GO, gene ontology, GOLGA4, Golgin A4, GRIN2A, Glutamate Ionotropic Receptor NMDA Type Subunit 2A, GSEA, gene set enrichment analysis, HERC5/6, HECT And RLD Domain Containing E3 Ubiquitin Protein Ligase 5/6, HEYL, Hes Related Family BHLH Transcription Factor With YRPW Motif Like, HPRT1, Hypoxanthine Phosphoribosyltransferase 1, HS, hot-spot, HSPA6, Heat Shock Protein Family A (Hsp70) Member 6, HUDD (ELAV4), Hu-Antigen D/ELAV Like Neuron-Specific RNA Binding Protein 4, IFI6, Interferon Alpha Inducible Protein 6, IFIH1 (MDA5), Interferon Induced With Helicase C Domain 1/Melanoma Differentiation-Associated Protein 5, IFIT1-3, Interferon Induced Protein With Tetratricopeptide Repeats 1–3, IFITM1/2, Interferon Induced Transmembrane Protein 1/2, IFN, interferon, IGB, Integrated Genome Browser, IL6, Interleukin 6, IR, intron retention, ISG20, Interferon Stimulated Exonuclease Gene 20, ISGF3, Interferon-Stimulated Gene Factor 3 Gamma, ISGs, interferon-stimulated genes, JEV, Japanese encephalitis virus, KCND2, Potassium Voltage-Gated Channel Subfamily D Member 2, KCNK10, Potassium Two Pore Domain Channel Subfamily K Member 10, KCNS2, Potassium Voltage-Gated Channel Modifier Subfamily S Member 2, KIT, KIT Proto-Oncogene, Receptor Tyrosine Kinase, KLHDC8A, Kelch Domain Containing 8A, KLHL13, Kelch Like Family Member 13, KRR1, KRR1 Small Subunit Processome Component Homolog, LCOR, Ligand Dependent Nuclear Receptor Corepressor, LEKR1, Leucine, Glutamate And Lysine Rich 1, LGI1, Leucine Rich Glioma Inactivated 1, LRRTM3, Leucine Rich Repeat Transmembrane Neuronal 3, LSV, local splicing variation, LUZP2, Leucine Zipper Protein 2, MAN1A1, Mannosidase Alpha Class 1A Member 1, MAP2, Microtubule Associated Protein 2, MBNL2, Muscleblind Like Splicing Regulator 2, MCTP1, Multiple C2 And Transmembrane Domain Containing 1, MMP13, Matrix Metallopeptidase 13, MN1, MN1 Proto-Oncogene, Transcriptional Regulator, MOI, multiplicity of infection, MTUS2, Microtubule Associated Scaffold Protein 2, MX2, MX Dynamin Like GTPase 2, MYCN, MYCN Proto-Oncogene, BHLH Transcription Factor, NAV1, Neuron Navigator 1, NCAM1, Neural Cell Adhesion Molecule 1, NDRG4, N-Myc Downstream-Regulated Gene 4 Protein, NEK7, NIMA Related Kinase 7, NFASC, Neurofascin, NKAIN1, Sodium/Potassium Transporting ATPase Interacting 1, NMI, N-Myc And STAT Interactor 2, NRAP, Nebulin Related Anchoring Protein, NRARP, NOTCH Regulated Ankyrin Repeat Protein, NREP, Neuronal Regeneration Related Protein, NRN1, Neuritin 1, NS3, flaviviral non-structural protein 3, NXPH2, Neurexophilin 2, NYNRIN, NYN Domain And Retroviral Integrase Containing, Neurons, Neuropathogenesis, OAS, 2′-5′-Oligoadenylate Synthetase, OASL, 2′-5′-Oligoadenylate Synthetase Like, ONECUT2, ONECUT-2 Homeodomain Transcription Factor, OPCML, Opioid Binding Protein/Cell Adhesion Molecule Like, OTX2, Orthodenticle Homeobox 2, PBS, phosphate buffer saline, PBX1, Pre-B-Cell Leukemia Transcription Factor 1, PCDH18/20, Protocadherin 18/20, PFKFB3, 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 3, PIK3C2B, Phosphatidylinositol-4-Phosphate 3-Kinase Catalytic Subunit Type 2 Beta, PIP4P2, Phosphatidylinositol-4,5-Bisphosphate 4-Phosphatase 2, PLCH1, Phospholipase C Eta 1, POU3F4, Brain-Specific Homeobox/POU Domain Protein 4, PPM1L, Protein Phosphatase, Mg2+/Mn2+ Dependent 1L, PPP1R17, Protein Phosphatase 1 Regulatory Subunit 17, PRDM12, PR Domain Zinc Finger Protein 12, PSI, percent selective index, PSRC1, Proline And Serine Rich Coiled-Coil 1, PTPN5, Protein Tyrosine Phosphatase Non-Receptor Type 5, PTPRH, Protein Tyrosine Phosphatase Receptor Type H, RAPGEF5, Rap Guanine Nucleotide Exchange Factor 5, RBFOX1, RNA Binding Fox-1 Homolog 1, RIG-I (DDX58), Retinoic Acid-Inducible Gene 1 Protein, RNF212, Ring Finger Protein 212, RNVU1, RNA, Variant U1 Small Nuclear, RSAD2, Radical S-Adenosyl Methionine Domain Containing 2, RTL8B, Retrotransposon Gag Like 8B, Response to infection, SAMD9, Sterile Alpha Motif Domain Containing 9, SEMA3E, Semaphorin 3E, SH3TC2, SH3 Domain And Tetratricopeptide Repeats 2, SHF, Src Homology 2 Domain Containing F, SHISAL1, Shisa Like 1, SIAH3, Siah E3 Ubiquitin Protein Ligase Family Member 3, SIRPA, Signal Regulatory Protein Alpha, SLITRK5, SLIT And NTRK Like Family Member 5, SNP, single-nucleotide polymorphism, SOGA1, Suppressor Of Glucose, Autophagy Associated 1, SPSB4, SplA/Ryanodine Receptor Domain And SOCS Box Containing 4, ST6GAL1, ST6 Beta-Galactoside Alpha-2,6-Sialyltransferase 1, TBC1D30, TBC1 Domain Family Member 30, TBEV, Tick-borne encephalitis virus, TFAP2A, Transcription Factor AP-2 Alpha, TFAP2B, Transcription Factor AP-2 Beta, THSD7A, Thrombospondin Type 1 Domain Containing 7A, THUMPD2, THUMP Domain-Containing Protein 2/SAM-Dependent Methyltransferase, TIPARP, TCDD Inducible Poly(ADP-Ribose) Polymerase, TM4SF18, Transmembrane 4 L Six Family Member 18, TMC8, Transmembrane Channel Like 6, TMEM229B, Transmembrane Protein 229B, TMTC1, Transmembrane O-Mannosyltransferase Targeting Cadherins 1, TNFSF10, TNF Superfamily Member 10, TRHDE, Thyrotropin Releasing Hormone Degrading Enzyme, TRIM38, Tripartite Motif Containing 38, TSHZ1, Teashirt Zinc Finger Homeobox 1, Tick-borne encephalitis virus, Transcriptomics, USP18, Ubiquitin Specific Peptidase 18/ISG15-Specific-Processing Protease, UTR, untranslated region, UTS2R, Urotensin 2 Receptor, WNV, West Nile virus, XAF1, XIAP Associated Factor 1, XRN1, 5′-3′ Exoribonuclease 1, ZIKV, Zika virus, ZMAT3, Zinc Finger Matrin-Type 3, ZMYM5, Zinc Finger MYM-Type Containing 5, ZNF124, Zinc Finger Protein 124, ZNF730, Zinc Finger Protein 730, gRNA, genomic TBEV RNA, hNSC, human neural stem cells, lncRNA, long non-coding RNA, mRNA, messenger RNA, miRNA, miRNA, micro RNA, ncRNA, non-coding RNA, pc-mRNA, protein-coding mRNA, qRT-PCR, quantitative reverse transcription real-time PCR, snRNP, small nuclear ribonucleoproteins, vd-sRNA, virus-derived small RNA,
• Publication type
• Journal Article MeSH

The aim of this review is to follow the history of studies on endemiv arboviruses and the diseases they cause which were detected in the Czech lands (Bohemia, Moravia and Silesia (i.e., the Czech Republic)). The viruses involve tick-borne encephalitis, West Nile and Usutu flaviviruses; the Sindbis alphavirus; Ťahyňa, Batai, Lednice and Sedlec bunyaviruses; the Uukuniemi phlebovirus; and the Tribeč orbivirus. Arboviruses temporarily imported from abroad to the Czech Republic have been omitted. This brief historical review includes a bibliography of all relevant papers.

• Keywords
• arthropods, birds, mammals, mosquitoes, ticks,
• MeSH
• Arbovirus Infections history   MeSH
• Arboviruses physiology   MeSH
• History, 20th Century MeSH
• History, 21st Century MeSH
• Humans MeSH
• Animals MeSH
• Check Tag
• History, 20th Century MeSH
• History, 21st Century MeSH
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Historical Article MeSH
• Review MeSH
• Geographicals
• Czech Republic epidemiology   MeSH

Tick-borne encephalitis virus (TBEV) is a leading cause of vector-borne viral encephalitis with expanding endemic regions across Europe. In this study we tested in mice the efficacy of preinfection with a closely related low-virulent flavivirus, Langat virus (LGTV strain TP21), or a naturally avirulent TBEV strain (TBEV-280) in providing protection against lethal infection with the highly virulent TBEV strain (referred to as TBEV-Hypr). We show that prior infection with TP21 or TBEV-280 is efficient in protecting mice from lethal TBEV-Hypr challenge. Histopathological analysis of brains from nonimmunized mice revealed neuronal TBEV infection and necrosis. Neuroinflammation, gliosis, and neuronal necrosis was however also observed in some of the TP21 and TBEV-280 preinfected mice although at reduced frequency as compared to the nonimmunized TBEV-Hypr infected mice. qPCR detected the presence of viral RNA in the CNS of both TP21 and TBEV-280 immunized mice after TBEV-Hypr challenge, but significantly reduced compared to mock-immunized mice. Our results indicate that although TBEV-Hypr infection is effectively controlled in the periphery upon immunization with low-virulent LGTV or naturally avirulent TBEV 280, it may still enter the CNS of these animals. These findings contribute to our understanding of causes for vaccine failure in individuals vaccinated with TBE vaccines.

• Keywords
• CNS, Langat virus, neuronal damage, tick-borne encephalitis virus, virus induced immunity,
• Publication type
• Journal Article MeSH

BACKGROUND: Tick-borne encephalitis (TBE) is a severe neuropathological disorder caused by tick-borne encephalitis virus (TBEV). Brain TBEV infection is characterized by extensive pathological neuroinflammation. The mechanism by which TBEV causes CNS destruction remains unclear, but growing evidence suggests that it involves both direct neuronal damage by the virus infection and indirect damage caused by the immune response. Here, we aimed to examine the TBEV-infection-induced innate immune response in mice and in human neural cells. We also compared cytokine/chemokine communication between naïve and infected neuronal cells and astrocytes. METHODS: We used a multiplexed Luminex system to measure multiple cytokines/chemokines and growth factors in mouse serum samples and brain tissue, and in human neuroblastoma cells (SK-N-SH) and primary cortical astrocytes (HBCA), which were infected with the highly pathogenic TBEV strain Hypr. We also investigated changes in cytokine/chemokine production in naïve HBCA cells treated with virus-free supernatants from TBEV-infected SK-N-SH cells and in naïve SK-N-SH cells treated with virus-free supernatants from TBEV-infected HBCA cells. Additionally, a plaque assay was performed to assess how cytokine/chemokine treatment influenced viral growth following TBEV infection. RESULTS: TBEV-infected mice exhibited time-dependent increases in serum and brain tissue concentrations of multiple cytokines/chemokines (mainly CXCL10/IP-10, and also CXCL1, G-CSF, IL-6, and others). TBEV-infected SK-N-SH cells exhibited increased production of IL-8 and RANTES and downregulated MCP-1 and HGF. TBEV infection of HBCA cells activated production of a broad spectrum of pro-inflammatory cytokines, chemokines, and growth factors (mainly IL-6, IL-8, CXCL10, RANTES, and G-CSF) and downregulated the expression of VEGF. Treatment of SK-N-SH with supernatants from infected HBCA induced expression of a variety of chemokines and pro-inflammatory cytokines, reduced SK-N-SH mortality after TBEV infection, and decreased virus growth in these cells. Treatment of HBCA with supernatants from infected SK-N-SH had little effect on cytokine/chemokine/growth factor expression but reduced TBEV growth in these cells after infection. CONCLUSIONS: Our results indicated that both neurons and astrocytes are potential sources of pro-inflammatory cytokines in TBEV-infected brain tissue. Infected/activated astrocytes produce cytokines/chemokines that stimulate the innate neuronal immune response, limiting virus replication, and increasing survival of infected neurons.

• Keywords
• Luminex, Neuroinflammation, Tick-borne encephalitis, Tick-borne encephalitis virus,
• MeSH
• Cytokines immunology   metabolism   MeSH
• Encephalitis, Tick-Borne immunology   metabolism   MeSH
• Humans MeSH
• Brain immunology   metabolism   pathology   MeSH
• Mice MeSH
• Neurons immunology   metabolism   virology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cytokines MeSH

BACKGROUND: The recent Zika virus (ZIKV) outbreak has linked ZIKV with microcephaly and other central nervous system pathologies in humans. Astrocytes are among the first cells to respond to ZIKV infection in the brain and are also targets for virus infection. In this study, we investigated the interaction between ZIKV and primary human brain cortical astrocytes (HBCA). RESULTS: HBCAs were highly sensitive to representatives of both Asian and African ZIKV lineages and produced high viral yields. The infection was associated with limited immune cytokine/chemokine response activation; the highest increase of expression, following infection, was seen in CXCL-10 (IP-10), interleukin-6, 8, 12, and CCL5 (RANTES). Ultrastructural changes in the ZIKV-infected HBCA were characterized by electron tomography (ET). ET reconstructions elucidated high-resolution 3D images of the proliferating and extensively rearranged endoplasmic reticulum (ER) containing viral particles and virus-induced vesicles, tightly juxtaposed to collapsed ER cisternae. CONCLUSIONS: The results confirm that human astrocytes are sensitive to ZIKV infection and could be a source of proinflammatory cytokines in the ZIKV-infected brain tissue.

• Keywords
• Astrocyte, Electron tomography, Flavivirus, Immune response, Luminex, Zika virus,
• MeSH
• Astrocytes virology   MeSH
• Cytokines metabolism   MeSH
• Endoplasmic Reticulum virology   MeSH
• Zika Virus Infection virology   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Brain virology   MeSH
• Zika Virus pathogenicity   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytokines MeSH

Tick-borne encephalitis virus (TBEV) is a member of the genus Flavivirus. It can cause serious infections in humans that may result in encephalitis/meningoencephalitis. Although several studies have described the involvement of specific genes in the host response to TBEV infection in the central nervous system (CNS), the overall network remains poorly characterized. Therefore, we investigated the response of DAOY cells (human medulloblastoma cells derived from cerebellar neurons) to TBEV (Neudoerfl strain, Western subtype) infection to characterize differentially expressed genes by transcriptome analysis. Our results revealed a wide panel of interferon-stimulated genes (ISGs) and pro-inflammatory cytokines, including type III but not type I (or II) interferons (IFNs), which are activated upon TBEV infection, as well as a number of non-coding RNAs, including long non-coding RNAs. To obtain a broader view of the pathways responsible for eliciting an antiviral state in DAOY cells we examined the effect of type I and III IFNs and found that only type I IFN pre-treatment inhibited TBEV production. The cellular response to TBEV showed only partial overlap with gene expression changes induced by IFN-β treatment - suggesting a virus-specific signature - and we identified a group of ISGs that were highly up-regulated following IFN-β treatment. Moreover, a high rate of down-regulation was observed for a wide panel of pro-inflammatory cytokines upon IFN-β treatment. These data can serve as the basis for further studies of host-TBEV interactions and the identification of ISGs and/or lncRNAs with potent antiviral effects in cases of TBEV infection in human neuronal cells.

• MeSH
• Transcriptional Activation MeSH
• Cytokines genetics   immunology   MeSH
• Host-Pathogen Interactions MeSH
• Interferons genetics   immunology   MeSH
• Encephalitis, Tick-Borne genetics   immunology   virology   MeSH
• Humans MeSH
• Neurons immunology   virology   MeSH
• Encephalitis Viruses, Tick-Borne genetics   physiology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cytokines MeSH
• Interferons MeSH