Project description:There has been an emergence and expansion of tick-borne diseases in Europe, Asia and North America in recent years, including Lyme disease, tick-borne encephalitis, and human anaplasmosis. The primary tick vectors implicated are hard ticks of the Ixodes genera. Although much is known about the host response to these bacterial and viral pathogens, there is limited knowledge of the cellular responses to infection within the tick vector. The bacterium Anaplasma phagocytophilum (A. phagocytophilum), is able to bypass apoptotic processes in ticks, enabling infection to proceed. However, the tick cellular responses to infection with the flaviviruses tick-borne encephalitis virus (TBEV) and louping ill virus (LIV), which cause tick-borne encephalitis and louping ill respectively, are less clear. Infection of an Ixodes ricinus (I. ricinus) tick cell line with the viruses LIV and TBEV, and the bacterium A. phagocytophilum, identified activation of common and distinct cellular pathways. In particular, commonly-upregulated genes included those that modulate apoptotic pathways (HSP70), putative anti-pathogen genes (FKBP and XBL1), and genes that influence the tick innate immune response, including selective activation of toll genes. These data provide an insight into potentially key genes involved in the tick cellular response to viral or bacterial infection.
Project description:Ixodes species ticks are competent vectors of tick-borne viruses including tick-borne encephalitis and Powassan encephalitis. Tick saliva has been shown to facilitate and enhance viral infection. This likely occurs by saliva-mediated modulation of host responses into patterns favorable for viral infection and dissemination. Because of the rapid kinetics of tick-borne viral transmission, this modulation must occur as early as tick attachment and initiation of feeding. In this study, the gene expression profile of cutaneous bite-site lesions created by uninfected ticks were analyzed at 1, 3, 6, and 12 hours after Ixodes scapularis nymphal tick attachment to discover host pathways or responses potentially important in tick-borne viral establishment.
Project description:Ixodes species ticks are competent vectors of tick-borne viruses including tick-borne encephalitis and Powassan encephalitis. Tick saliva has been shown to facilitate and enhance viral infection. This likely occurs by saliva-mediated modulation of host responses into patterns favorable for viral infection and dissemination. Because of the rapid kinetics of tick-borne viral transmission, this modulation must occur as early as tick attachment and initiation of feeding. In this study, the gene expression profile of cutaneous bite-site lesions created by uninfected ticks were analyzed at 1, 3, 6, and 12 hours after Ixodes scapularis nymphal tick attachment to discover host pathways or responses potentially important in tick-borne viral establishment. Four milimeter ear biopsies from BALB/cJ mice infested with Ixodes scapularis nymphs were assayed using Affymetrix genechip 430A 2.0 arrays at 1, 3, 6, and 12 hours after infestation during a primary exposure. 3 mice were measured at each time point. Controls were 3 similarly housed but tick-free mice.
Project description:Flavivirus non-structural protein 1 (NS1) is secreted from cells in infected individuals and in cell culture and levels correlate with disease severity. Treatment of murine bone marrow–derived dendritic cells (BMDCs) with recombinantly produced solube NS1 (sNS1) of tick-borne encephalitis virus (TBEV) or West Nile virus (WNV) prior to poly(I:C) stimulation revealed two gene clusters that were downregulated by TBEV or WNV sNS1 and that were associated with innate and adaptive immune responses. Especially co-stimulatory molecules and pro-inflammatory cytokines as well as chemokines were found to be downregulated in sNS1 pre-treated BMDCs prior to poly(I:C) stimulation.
Project description:Tick-borne diseases (TBDs) are the most common illnesses transmitted by ticks, and the annual number of reported TBD cases continues to increase. The Asian longhorned tick, a vector associated with at least 30 human pathogens, is native to eastern Asia and recently reached the USA as an emerging disease threat. Newly identified tick-transmitted pathogens continue to be reported, raising concerns about how TBDs occur. Interestingly, tick can harbor pathogens without being affected themselves. For viral infections, ticks have their own immune systems that protect them from infection. Meanwhile, tick-borne viruses have evolved to avoid these defenses as they establish themselves within the vector. Here, we show in detail that infecting longhorned ticks with distinct arthropod-borne RNA viruses through two approaches natural blood feeding and injection, all induce the production of vsiRNAs. Dicer2-like homolog plays a role in regulating antiviral RNAi responses as knocking down of this gene enhanced viral replication. Furthermore, we demonstrate that tick antiviral RNAi responses are inhibited through expression heterologous VSR proteins in recombinant SINV. We identify both the virus and tick factors are critical components to understanding TBDs. Importantly, our study introduces a novel, in vivo virus-vector-mouse model system for exploring TBDs in the future.
Project description:Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes severe clinical symptoms and mortality in humans. Haemaphysalis longicornis tick has been identified as the competent vector for SFTSV transmission. Although antiviral RNA interference (RNAi) in insects has been well documented, the degree to which RNAi contributes to antiviral defense in ticks is still largely elusive. In this study, utilizing arthropod-borne RNA viruses, including SFTSV, we find abundant virus-derived small interfering RNAs (vsiRNAs) are induced in H. longicornis after infection through either microinjection or natural blood-feeding. Furthermore, we identify a Dicer2-like homolog, the core protein of antiviral RNAi pathway, in H. longicornis and knocking down this gene exacerbated virus amplification. To counteract this antiviral RNAi of ticks, viruses have evolved suppressors of RNAi (VSRs). Here, we show that reduced viral replication inversely correlated with the accumulation of vsiRNAs in ticks after infection with recombinant sindbis virus (SINV) expressing heterologous VSR proteins. Elucidating the antiviral RNAi pathway of ticks by model arthropod-borne RNA viruses in vivo is critical to understanding the virus-host interaction, providing a feasible intervention strategy to control tick-borne arbovirus transmission.
Project description:There are very few studies exploring the genetic diversity of tick-borne encephalitis complex viruses. Most of the viruses have been sequenced using capillary electrophoresis, however, very few viruses have been analyzed using deep sequencing to look at the genotypes in each virus population. In this study, different viruses and strains belonging to the tick-borne encephalitis complex were sequenced and genetic diversity was analyzed. Shannon entropy and single nucleotide variants were used to compare the viruses. Then genetic diversity was compared to the phylogenetic relationship of the viruses.
Project description:Upon tick borne encephalitis virus exposure of brain-resident cells, astrocytes are important IFN-β producers that followed a biphasic response, which initially depends on MAVS- and later on MyD88/TRIF-signaling
Project description:Tick saliva contains many bioactive molecules that are involved in attachment to the host, blood feeding and transmission of pathogens. MicroRNAs (miRNAs) are a class of short non-coding RNAs with a length of 19-24 nucleotides. They act as regulators of gene expression by binding to their target mRNA at the post-transcriptional level and control a variety of cellular functions, including regulation of growth, metabolism, and development. The detection and characterizations of miRNAs from tick saliva may help explain the molecular mechanisms involved in the interaction between ticks, pathogens, and hosts. They may also contribute to the discovery of vaccines, which can control ticks and the pathogens they transmit. An RNA library was generated from the saliva of fed adult Haemaphysalis longicornis ticks, and it contained 17.4 million clean reads of 18-30 nucleotides. Overall, 319 known miRNAs and 1 novel miRNA were found. The 10 most abundantly expressed miRNAs present in tick saliva were miR-100_2, miR-315, miR-184_1, miR-100-5p_2, miR-5307, miR-184-3p_3, Let-7-5p_6, miR-71_5, miR-1-3p_6, and miR-10-5p_2. The miR-375, one of the abundantly expressed, was subjected to Quantitative Real-Time PCR analysis (qRT-PCR) in various tick developmental stages, as well as in different tissues isolated from adult ticks. The expression of miR-375 in different tick development stages was highest in unfed nymphs and lowest in the egg stage. In the tissues of adult ticks, miR-375 was most highly expressed in the salivary gland. To investigate the possible role of miR-375, Ant-375 was used to inhibit the miR-375. Treated group (Ant-375) had a reduced number of eggs (t(10)= 2.652, P=0.0242), eggs that were partially desiccated, and reduced egg hatchability (t(10)=2.272, P=0.044) compared to Ms-Ant and the non-injected control. This is the first study to investigate the miRNAs profile in tick saliva and the role of miR-375 in H. longicornis. The identification and characterization of miRNA in tick saliva may help to reveal the molecular mechanisms of interactions among ticks, pathogens, and hosts and suggest new vaccine strategies to control tick borne diseases.