Lindqvist R, Mundt F, Gilthorpe JD, Wölfel S, Gekara NO, Kröger A, Överby AK.
J Neuroinflammation. 2016 Oct 24;13(1):277.
Abstract
BACKGROUND: Neurotropic flaviviruses such as tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV), West Nile virus (WNV), and Zika virus (ZIKV) are causative agents of severe brain-related diseases including meningitis, encephalitis, and microcephaly. We have previously shown that local type I interferon response within the central nervous system (CNS) is involved in the protection of mice against tick-borne flavivirus infection. However, the cells responsible for mounting this protective response are not defined.
METHODS: Primary astrocytes were isolated from wild-type (WT) and interferon alpha receptor knock out (IFNAR-/-) mice and infected with neurotropic flaviviruses. Viral replication and spread, IFN induction and response, and cellular viability were analyzed. Transcriptional levels in primary astrocytes treated with interferon or supernatant from virus-infected cells were analyzed by RNA sequencing and evaluated by different bioinformatics tools.
RESULTS:Here, we show that astrocytes control viral replication of different TBEV strains, JEV, WNV, and ZIKV. In contrast to fibroblast, astrocytes mount a rapid interferon response and restrict viral spread. Furthermore, basal expression levels of key interferon-stimulated genes are high in astrocytes compared to mouse embryonic fibroblasts. Bioinformatic analysis of RNA-sequencing data reveals that astrocytes have established a basal antiviral state which contributes to the rapid viral recognition and upregulation of interferons. The most highly upregulated pathways in neighboring cells were linked to type I interferon response and innate immunity. The restriction in viral growth was dependent on interferon signaling, since loss of the interferon receptor, or its blockade in wild-type cells, resulted in high viral replication and virus-induced cytopathic effects. Astrocyte supernatant from TBEV-infected cells can restrict TBEV growth in astrocytes already 6 h post infection, the effect on neurons is highly reinforced, and astrocyte supernatant from 3 h post infection is already protective.
CONCLUSIONS:These findings suggest that the combination of an intrinsic constitutive antiviral response and the fast induction of type I IFN production by astrocytes play an important role in self-protection of astrocytes and suppression of flavivirus replication in the CNS.
2.
Kurhade C, Zegenhagen L, Weber E, Nair S, Michaelsen-Preusse K, Spanier J, Gekara NO, Kröger A, Överby AK.
J Neuroinflammation. 2016 Jan 27;13:22. doi: 10.1186/s12974-016-0487-9.
Abstract
BACKGROUND: Although type I interferons (IFNs)-key effectors of antiviral innate immunity are known to be induced via different pattern recognition receptors (PRRs), the cellular source and the relative contribution of different PRRs in host protection against viral infection is often unclear. IPS-1 is a downstream adaptor for retinoid-inducible gene I (RIG-I)-like receptor signaling. In this study, we investigate the relative contribution of IPS-1 in the innate immune response in the different brain regions during infection with tick-borne encephalitis virus (TBEV), a flavivirus that causes a variety of severe symptoms like hemorrhagic fevers, encephalitis, and meningitis in the human host.
METHODS: IPS-1 knockout mice were infected with TBEV/Langat virus (LGTV), and viral burden in the peripheral and the central nervous systems, type I IFN induction, brain infiltrating cells, and inflammatory response was analyzed.
RESULTS: We show that IPS-1 is indispensable for controlling TBEV and LGTV infections in the peripheral and central nervous system. Our data indicate that IPS-1 regulates neuropathogenicity in mice. IFN response is differentially regulated in distinct regions of the central nervous system (CNS) influencing viral tropism, as LGTV replication was mainly restricted to olfactory bulb in wild-type (WT) mice. In contrast to the other brain regions, IFN upregulation in the olfactory bulb was dependent on IPS-1 signaling. IPS-1 regulates basal levels of antiviral interferon-stimulated genes (ISGs) like viperin and IRF-1 which contributes to the establishment of early viral replication which inhibits STAT1 activation. This diminishes the antiviral response even in the presence of high IFN-β levels. Consequently, the absence of IPS-1 causes uncontrolled virus replication, in turn resulting in apoptosis, activation of microglia and astrocytes, elevated proinflammatory response, and recruitment of inflammatory cells into the CNS.
CONCLUSIONS: We show that LGTV replication is restricted to the olfactory bulb and that IPS-1 is a very important player in the olfactory bulb in shaping the innate immune response by inhibiting early viral replication and viral spread throughout the central nervous system. In the absence of IPS-1, higher viral replication leads to the evasion of antiviral response by inhibiting interferon signaling. Our data suggest that the local microenvironment of distinct brain regions is critical to determine virus permissiveness.
3.
Sedenkova
KN, Dueva EV, Averina EB, Grishin YK, Osolodkin DI, Kozlovskaya LI,
Palyulin VA, Savelyev EN, Orlinson BS, Novakov IA, Butov GM, Kuznetsova
TS, Karganova GG, Zefirov NS.
Org Biomol Chem. 2015 Mar 21;13(11):3406-15. doi: 10.1039/c4ob02649g.
Tick-borne encephalitis virus (TBEV) belonging to Flavivirus genus causes severe infection in humans. The search for therapeutically relevant compounds targeting TBEV
requires the exploration of novel chemotypes. A versatile synthesis of
previously unknown 4-aminopyrimidines and 4-aminopyrimidine N-oxides
based on a fluorosubstituted heterocyclic core is described. A
representative series of 4-aminotetrahydroquinazoline derivatives,
containing aliphatic and aromatic substituents as well as the adamantane
framework, was obtained and their activity against tick-borne encephalitis virus reproduction was studied. Nine compounds were found to inhibit TBEV entry into the host cells. A bulky hydrophobic adamantyl group was identified to be important for the antiviral
activity. The developed synthetic route allowed an easy access to a
consistent compound library for further structure-activity relationship
studies.
4.
Weber E, Finsterbusch K, Lindquist R, Nair S, Lienenklaus S, Gekara NO, Janik D, Weiss S, Kalinke U, Överby AK, Kröger A.
J Virol. 2014 Nov;88(21):12202-12. doi: 10.1128/JVI.01215-14. Epub 2014 Aug 13.
Vector-borne flaviviruses, such as tick-borne encephalitis virus (TBEV), West Nile virus, and dengue virus, cause millions of infections in humans. TBEV
causes a broad range of pathological symptoms, ranging from meningitis
to severe encephalitis or even hemorrhagic fever, with high mortality.
Despite the availability of an effective vaccine, the incidence of TBEV infections is increasing. Not much is known about the role of the innate immune system in the control of TBEV infections. Here, we show that the type I interferon (IFN) system is essential for protection against TBEV
and Langat virus (LGTV) in mice. In the absence of a functional IFN
system, mice rapidly develop neurological symptoms and succumb to LGTV
and TBEV
infections. Type I IFN system deficiency results in severe
neuroinflammation in LGTV-infected mice, characterized by breakdown of
the blood-brain barrier and infiltration of macrophages into the central
nervous system (CNS). Using mice with tissue-specific IFN receptor
deletions, we show that coordinated activation of the type I IFN system
in peripheral tissues as well as in the CNS is indispensable for viral
control and protection against virus induced inflammation and fatal encephalitis.
IMPORTANCE: The type I interferon (IFN) system is important to control viral infections; however, the interactions between tick-borne encephalitis virus (TBEV) and the type I IFN system are poorly characterized. TBEV causes severe infections in humans that are characterized by fever and debilitating encephalitis, which can progress to chronic illness or death. No treatment options are available. An improved understanding of antiviral innate immune responses is pivotal for the development of effective therapeutics. We show that type I IFN, an effector molecule of the innate immune system, is responsible for the extended survival of TBEV and Langat virus (LGTV), an attenuated member of the TBE serogroup. IFN production and signaling appeared to be essential in two different phases during infection. The first phase is in the periphery, by reducing systemic LGTV replication and spreading into the central nervous system (CNS). In the second phase, the local IFN response in the CNS prevents virus-induced inflammation and the development of encephalitis.
Free PMC Article
5.
De
Burghgraeve T, Kaptein SJ, Ayala-Nunez NV, Mondotte JA, Pastorino B,
Printsevskaya SS, de Lamballerie X, Jacobs M, Preobrazhenskaya M,
Gamarnik AV, Smit JM, Neyts J.
PLoS One. 2012;7(5):e37244. doi: 10.1371/journal.pone.0037244. Epub 2012 May 18.
There is an urgent need for potent inhibitors of dengue virus (DENV)
replication for the treatment and/or prophylaxis of infections with this
virus. We here report on an aglycon analogue of the antibiotic
teicoplanin (code name LCTA-949) that inhibits DENV-induced cytopathic
effect (CPE) in a dose-dependent manner. Virus infection was completely
inhibited at concentrations that had no adverse effect on the host
cells. These findings were corroborated by quantification of viral RNA
levels in culture supernatant. Antiviral activity was also observed against other flaviviruses such as the yellow fever virus and the tick-borne encephalitis virus (TBEV). In particular, potent antiviral activity was observed against TBEV.
Time-of-drug-addition experiments indicated that LCTA-949 inhibits an
early stage in the DENV replication cycle; however, a virucidal effect
was excluded. This observation was corroborated by the fact that
LCTA-949 lacks activity on DENV subgenomic replicon (that does not
encode structural proteins) replication. Using a microscopy-based binding
and fusion assay employing DiD-labeled viruses, it was shown that
LCTA-949 targets the early stage (binding/entry) of the infection.
Moreover, LCTA-949 efficiently inhibits infectivity of DENV particles
pre-opsonized with antibodies, thus potentially also inhibiting
antibody-dependent enhancement (ADE). In conclusion, LCTA-949 exerts in
vitro activity against several flaviviruses and does so (as shown for DENV) by interfering with an early step in the viral replication cycle.Free PMC Article
6.
Aberle JH, Aberle SW, Kofler RM, Mandl CW.
J Virol. 2005 Dec;79(24):15107-13.
A new vaccination principle against flaviviruses, based on a tick-borne encephalitis virus (TBEV)
self-replicating noninfectious RNA vaccine that produces subviral
particles, has recently been introduced (R. M. Kofler, J. H. Aberle, S.
W. Aberle, S. L. Allison, F. X. Heinz, and C. W. Mandl, Proc. Natl.
Acad. Sci. USA 7:1951-1956, 2004).
In this study, we evaluated the potential of the self-replicating RNA vaccine in mice in comparison to those of live, attenuated vaccines and a formalin-inactivated whole-virus vaccine (ImmunInject). For this purpose, mice were immunized using gene gun-mediated application of the RNA vaccine and tested for CD8+ T-cell responses, long-term duration, neutralizing capacity, and isotype profile of specific antibodies and protection against lethal virus challenge. We demonstrate that the self-replicating RNA vaccine induced a broad-based, humoral and cellular (Th1 and CD8+ T-cell response) immune response comparable to that induced by live vaccines and that it protected mice from challenge. Even a single immunization with 1 microg of the replicon induced a long-lasting antibody response, characterized by high neutralizing antibody titers, which were sustained for at least 1 year. Nevertheless, it was possible to boost this response further by a second injection with the RNA vaccine, even in the presence of a concomitant CD8+ T-cell response. In this way it was possible to induce a balanced humoral and cellular immune response, similar to infection-induced immunity but without the safety hazards of infectious agents. The results also demonstrate the value of TBEV replicon RNA for inducing protective long-lasting antiviral responses.
In this study, we evaluated the potential of the self-replicating RNA vaccine in mice in comparison to those of live, attenuated vaccines and a formalin-inactivated whole-virus vaccine (ImmunInject). For this purpose, mice were immunized using gene gun-mediated application of the RNA vaccine and tested for CD8+ T-cell responses, long-term duration, neutralizing capacity, and isotype profile of specific antibodies and protection against lethal virus challenge. We demonstrate that the self-replicating RNA vaccine induced a broad-based, humoral and cellular (Th1 and CD8+ T-cell response) immune response comparable to that induced by live vaccines and that it protected mice from challenge. Even a single immunization with 1 microg of the replicon induced a long-lasting antibody response, characterized by high neutralizing antibody titers, which were sustained for at least 1 year. Nevertheless, it was possible to boost this response further by a second injection with the RNA vaccine, even in the presence of a concomitant CD8+ T-cell response. In this way it was possible to induce a balanced humoral and cellular immune response, similar to infection-induced immunity but without the safety hazards of infectious agents. The results also demonstrate the value of TBEV replicon RNA for inducing protective long-lasting antiviral responses.
7.
Gritsun TS, Lashkevich VA, Gould EA.
Antiviral Res. 2003 Jan;57(1-2):129-46. Review.
Abstract Tick-borne encephalitis
(TBE) is one of the most dangerous human infections occurring in Europe
and many parts of Asia. The etiological agent Tick-borne encephalitis virus (TBEV), is a member of the virus genus Flavivirus, of the family Flaviviridae. TBEV
is believed to cause at least 11,000 human cases of encephalitis in
Russia and about 3000 cases in the rest of Europe annually. Related
viruses within the same group, Louping ill virus (LIV), Langat virus
(LGTV) and Powassan virus (POWV), also cause human encephalitis but
rarely on an epidemic scale. Three other viruses within the same group,
Omsk hemorrhagic fever virus (OHFV), Kyasanur Forest disease virus
(KFDV) and Alkhurma virus (ALKV), are closely related to the TBEV
complex viruses and tend to cause fatal hemorrhagic fevers rather than
encephalitis. This review describes the clinical manifestations
associated with TBEV
infections, the main molecular-biological properties of these viruses,
and the different factors that define the incidence and severity of
disease. The role of ticks and their local hosts in the emergence of new
virus variants with different pathogenic characteristics is also
discussed. This review also contains a brief history of vaccination against TBE including trials with live attenuated vaccine and modern tendencies in developing of vaccine virus strains.
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