Analysis of tick-borne encephalitis virus-induced host responses in human cells of neuronal origin and interferon-mediated protection.

Martin Selinger,Esther Schnettler,Libor Grubhoffer,Alain Kohl,Quan Gu,Gavin S Wilkie,Lily Tong

doi:10.1099/jgv.0.000853

Abstract

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.

Highlights

Tick-borne encephalitis virus (TBEV) is a medically important tick-borne flavivirus and is the causative agent of tickborne encephalitis (TBE)
As TBEV infection can result in central nervous system (CNS) damage, we studied the antiviral host response against TBEV strain Neudoerfl (Western subtype) in vitro in the human medulloblastomaderived neuronal cell line, DAOY HTB-186
In order to determine the infection rate of TBEV Neudoerfl, DAOY cells were infected at a multiplicity of infection (m.o.i.) of 0.1, 1, and 5, respectively, and levels of viral NS3 protein were analysed at 24 h post infection (h p.i.) using an immunofluorescence assay

Summary

Introduction

Tick-borne encephalitis virus (TBEV) is a medically important tick-borne flavivirus and is the causative agent of tickborne encephalitis (TBE). TBE is widespread in Europe and North Asia, and more than 10 000 cases per year are reported [1]. The Czech Republic has the second highest incidence of TBE in Europe after Russia [2]. The clinical outcome of TBE can vary from sub-clinical cases to severe encephalitis/meningoencephalitis. The European subtype of TBEV is associated with a high ratio of sub-clinical or asymptomatic cases (estimated 70–95 %). Neurologic sequelae were reported in up to 30 % of the patients and the case fatality in adult patients is

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Conclusion