Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off

Transcriptomic and proteomic analysis of arbovirus-infected tick cells

Ticks are important vectors of a wide variety of pathogens including protozoa, bacteria and viruses. Many of the viruses transmitted by ticks are of medical or veterinary importance including tick-borne encephalitis virus (TBEV) and Crimean- Congo hemorrhagic fever virus causing disease in humans, and African swine fever virus and Nairobi sheep disease virus affecting livestock. Although several studies have elucidated tick antimicrobial mechanisms including cellular immune responses such as nodulation, encapsulation and phagocytosis and humoral immune responses such as the JAK/STAT pathway, complement-like proteins, antimicrobial peptides, lectin like pattern-recognition molecules and lysozymes, very little is known about the innate immune response of ticks towards viral infection. This study therefore aimed to identify molecules that might be involved in the response of ticks to viral infection. The hypothesis was that TBEV infection leads to changes in the expression of immunity-related transcripts and proteins in Ixodes spp. tick cells and that at least some of these might be antiviral. Ixodes scapularis-derived cell lines IDE8 and ISE6 were chosen since I. scapularis is currently the only tick species with a sequenced genome and an Ixodes ricinus-derived cell line, IRE/CTVM19, was used because I. ricinus is the natural vector of TBEV. Basic parameters required to study the responses of tick cells to infection were determined, including levels of virus infection, kinetics of virus replication and production, formation of replication complexes and uptake of dsRNA or siRNA. The cell lines IDE8, ISE6 and IRE/CTVM19 were infected with either of two tick-borne flaviviruses, TBEV and Langat virus (LGTV), or with the mosquito-borne alphavirus Semliki Forest virus (SFV). Infection was characterised using techniques including plaque assay, luciferase assay, immunostaining and conventional, confocal and electron microscopy. Two time points for transcriptomics and proteomics analysis of TBEVinfected IDE8 and IRE/CTVM19 cells were selected: day 2 post-infection (p.i.) when virus production was increasing and day 6 p.i. when virus production was decreasing. RNA and protein were isolated from TBEV-infected and mock-infected tick cells at days 2 and 6 p.i. and RNA-Seq and mass spectrometric technologies were used to identify changes in, respectively, transcript and protein abundance. Differential expression of transcripts was determined using the data analysis package DESeq resulting in a total of 43 statistically significantly differentially expressed transcripts in IDE8 cells and 83 in IRE/CTVM19 cells, while differential protein representation using Χ2 test statistics with Bonferroni correction in IDEG6 software resulted in 76 differentially represented proteins in IDE8 cells and 129 in IRE/CTVM19 cells. These included transcripts and proteins which could affect stages of the virus infection, including virus entry, replication, maturation and protein trafficking, and also innate immune responses such as phagocytosis, RNA interference (RNAi), the complement system, the ubiquitin-proteasome pathway, cell stress and the endoplasmic reticulum (ER) stress response. After verification of sequencing data by qRT-PCR, the ability of several of the identified transcripts or proteins to affect virus infection was determined by knockdown experiments in IDE8 and IRE/CTVM19 cells using wild type LGTV, LGTV replicons or TBEV replicons. Knockdown of genes encoding proteins including the ER chaperone gp96 and the heat-shock protein HSP90 resulted in increased virus production in both cell lines, hinting at an antiviral role. In contrast, knockdown of calreticulin, another ER chaperone, resulted in a decrease in virus production in IRE/CTVM19 cells but not in IDE8 cells, implying a requirement for virus production. This functional genomics approach has identified possible novel genes/proteins involved in the interaction between flaviviruses and tick cells and also revealed that there might be antiviral innate immune pathways present in ticks additional to the exogenous RNAi pathway

The influence of salivary gland extracts (SGE) and saliva of the tick \kur{Ixodes ricinus} on the replication of tick-borne encephalitis virus under \kur{in vitro} conditions

We examined the influence of saliva and SGE from Ixodes ricinus tick, the main European TBEV vector, on the replication of TBEV under in vitro conditions in various mammalian cell lines (fibroblasts, macrophages, porcine kidney). In addition, the effect of tick saliva on the production of IFN {$\beta$} by fibroblast cells was studied

Interaction of tick-borne encephalitis virus with host and vector cells

The proposed thesis deals with the various aspects of tick-borne encephalitis virus infection in the host and the vector on the cellular level. It uncovers transcriptomic and proteomic responses in infected cells in the human neurons and astrocytes, and vector cells. It identifies the subgenomic flaviviral RNA as an important pathogenesis effector that can interfere with the vector RNAi pathway, and at the same time denotes the components of this pathway. It also describes the phenomenon of impairment of host protein and rRNA synthesis upon TBEV infection. Moreover, it uncovers the importance of quasispecies in the adaptation to vector and host cells

Changes in global gene expression in human neural cells following tick-borne encephalitis virus infection

Our study was focused on the effect of tick-borne encephalitis virus infection on global gene expression in two human neural cell lines (neuroblastoma and glioblastoma). Changes of gene expression were determined using microarray approach. We identified several genes with up-or down-regulated expression in neural cells following the infection. The changes in expression of some of them were similar in both cell lines,other exhibited different pattern

Ticks and tick-borne pathogens in South Bohemia (Czech Republic) - Spatial variability in Ixodes ricinus abundance, Borrelia burgdorferi and tick-borne encephalitis virus prevalence

PubMed ID: 25976235Spatial distribution of Ixodes ricinus tick host-seeking activity, as well as prevalence of Borrelia burgdorferi sensu lato and tick-borne encephalitis virus (TBEV) were studied in the TBE endemic area of South Bohemia (Czech Republic). High variability in tick abundance detected in a network of 30 study sites was most closely associated with characteristics of vegetation cover. Of 11,182 tested tick samples, 12% carried DNA of spirochete from B. burgdorferi s.l. complex. B. afzelii and B. garinii prevailed among spirochete species. The presence of B. spielmanii in the region was confirmed. The median number of borrelial genome copies in positive samples reached 6.6 × 103 by real-time PCR. The total prevalence of TBEV in pooled samples reached 0.32% (20,057 samples tested), at least one TBEV positive tick was present in 21 out of 30 sampling sites.Web of Science6556755

Pressing the Nuts to Sheet Metal Blanks

The bachelor thesis consists of the theoretical introduction into pressing the nuts, familiarization with used machines followed by testing and evaluating of outcomes. Pressing the nuts is tested for torque and pulling force. In the practical part of the thesis chosen press nuts will be tested. Objective of this thesis is to find out suitable pressing parameters, which can substitute present unsuitable practices

Additional file 3: of Ixodes scapularis and Ixodes ricinus tick cell lines respond to infection with tick-borne encephalitis virus: transcriptomic and proteomic analysis

TBEV infection levels in mock-infected and TBEV-infected tick cells. Numbers of copies of TBEV NS5 were determined by qRT-PCR using NS5 primers and the linearised plasmid pJET-NS5 to create a standard curve. Copy numbers were normalised to 1 μg of total RNA. The limit of detection was derived from the number of NS5 copies in the highest dilution which was still detectable with a variance less than one Ct and was normalised to 1 μg of total RNA. (A) IDE8 infected and mock-infected (control) at days 2 (2d) and 6 (6d) p.i. (B) IRE/CTVM19 infected and mock-infected (control) at days 2 and 6 p.i.. Error bars are standard deviations. Samples marked with + passed both RNA and protein quality checks and were used in transcriptomic and proteomic analyses