Neurological disease caused by flavivirus infections

2018 ◽  
Vol 39 (2) ◽  
pp. 99
Author(s):  
Tristan Gibbs ◽  
David J Speers
Keyword(s):  
South America ◽  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Zika Virus ◽  
Neurological Disease ◽  
Febrile Illness ◽  
Encephalitis Virus ◽  
Murray Valley Encephalitis Virus ◽  
Neurological Sequelae ◽  
Virus West Nile

The Flavivirus genus contains dozens of species with varying geographical distributions. Most flavivirus infections in humans are asymptomatic or manifest as a non-specific febrile illness, sometimes accompanied by rash or arthralgia. Certain species are more commonly associated with neurological disease and may be termed neurotropic flaviviruses. Several flaviviruses endemic to Australia and our near northern neighbours are neurotropic, such as Murray Valley encephalitis virus, West Nile (Kunjin) virus and Japanese encephalitis virus. Flavivirus neurological disease ranges from self-limiting meningitis to fulminant encephalitis causing permanent debilitating neurological sequelae or death. The recent Zika virus outbreak in South America has highlighted the dramatic effects of flavivirus neurotropism on the developing brain. This article focuses on the neurotropic flaviviruses endemic to Australia and those of international significance.

scholarly journals Live Chimeric and Inactivated Japanese Encephalitis Virus Vaccines Differ in Their Cross-Protective Values against Murray Valley Encephalitis Virus

2008 ◽  
Vol 83 (6) ◽  
pp. 2436-2445 ◽  
Author(s):  
Mario Lobigs ◽  
Maximilian Larena ◽  
Mohammed Alsharifi ◽  
Eva Lee ◽  
Megan Pavy
Keyword(s):  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Protective Immunity ◽  
Encephalitis Virus ◽  
Type I ◽  
Murray Valley Encephalitis Virus ◽  
Lethal Challenge ◽  
Live Virus ◽  
Immunodeficient Mice ◽  
The Cross

ABSTRACT The Japanese encephalitis virus (JEV) serocomplex, which also includes Murray Valley encephalitis virus (MVEV), is a group of antigenically closely related, mosquito-borne flaviviruses that are responsible for severe encephalitic disease in humans. While vaccines against the prominent members of this serocomplex are available or under development, it is unlikely that they will be produced specifically against those viruses which cause less-frequent disease, such as MVEV. Here we have evaluated the cross-protective values of an inactivated JEV vaccine (JE-VAX) and a live chimeric JEV vaccine (ChimeriVax-JE) against MVEV in two mouse models of flaviviral encephalitis. We show that (i) a three-dose vaccination schedule with JE-VAX provides cross-protective immunity, albeit only partial in the more severe challenge model; (ii) a single dose of ChimeriVax-JE gives complete protection in both challenge models; (iii) the cross-protective immunity elicited with ChimeriVax-JE is durable (≥5 months) and broad (also giving protection against West Nile virus); (iv) humoral and cellular immunities elicited with ChimeriVax-JE contribute to protection against lethal challenge with MVEV; (v) ChimeriVax-JE remains fully attenuated in immunodeficient mice lacking type I and type II interferon responses; and (vi) immunization with JE-VAX, but not ChimeriVax-JE, can prime heterologous infection enhancement in recipients of vaccination on a low-dose schedule, designed to mimic vaccine failure or waning of vaccine-induced immunity. Our results suggest that the live chimeric JEV vaccine will protect against other viruses belonging to the JEV serocomplex, consistent with the observation of cross-protection following live virus infections.

scholarly journals Japanese encephalitis virus–primed CD8+ T cells prevent antibody-dependent enhancement of Zika virus pathogenesis

2020 ◽  
Vol 217 (9) ◽  
Author(s):  
Dong Chen ◽  
Zhiliang Duan ◽  
Wenhua Zhou ◽  
Weiwei Zou ◽  
Shengwei Jin ◽  
...  
Keyword(s):  
T Cells ◽  
Viral Replication ◽  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Cd8 T Cells ◽  
Zika Virus ◽  
Encephalitis Virus ◽  
Protective Effects ◽  
Zikv Infection ◽  
Lethal Effects

Cross-reactive anti-flaviviral immunity can influence the outcome of infections with heterologous flaviviruses. However, it is unclear how the interplay between cross-reactive antibodies and T cells tilts the balance toward pathogenesis versus protection during secondary Zika virus (ZIKV) and Japanese encephalitis virus (JEV) infections. We show that sera and IgG from JEV-vaccinated humans and JEV-inoculated mice cross-reacted with ZIKV, exacerbated lethal ZIKV infection upon transfer to mice, and promoted viral replication and mortality upon ZIKV infection of the neonates born to immune mothers. In contrast, transfer of CD8+ T cells from JEV-exposed mice was protective, reducing the viral burden and mortality of ZIKV-infected mice and abrogating the lethal effects of antibody-mediated enhancement of ZIKV infection in mice. Conversely, cross-reactive anti-ZIKV antibodies or CD8+ T cells displayed the same pathogenic or protective effects upon JEV infection, with the exception that maternally acquired anti-ZIKV antibodies had no effect on JEV infection of the neonates. These results provide clues for developing safe anti-JEV/ZIKV vaccines.

scholarly journals Cross-Protection Against Zika Virus Infection Conferred by a Live Attenuated Japanese Encephalitis SA14-14-2 Vaccine

2020 ◽  
Author(s):  
Ran Wang ◽  
Zida Zhen ◽  
Lance Turtle ◽  
Baohua Hou ◽  
Yueqi Li ◽  
...  
Keyword(s):  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Cellular Immunity ◽  
Zika Virus ◽  
T Cell Response ◽  
Encephalitis Virus ◽  
Cross Protection ◽  
World Health ◽  
Effective Vaccine ◽  
Zikv Infection

AbstractZika virus (ZIKV) and Japanese encephalitis virus (JEV) are closely related mosquito-borne flaviviruses. Japanese encephalitis (JE) vaccine SA14-14-2 has been in the Chinese national Expanded Program on Immunization since 2007. The recent recognition of severe disease syndromes associated with ZIKV, and the identification of ZIKV from mosquitoes in China, prompts an urgent need to investigate the potential interaction between the two. In this study, we showed that SA14-14-2 is protective against ZIKV infection in mice. JE vaccine SA14-14-2 triggered both Th1 and Th2 cross-reactive immune responses to ZIKV; however, it was cellular immunity that predominantly mediated cross-protection against ZIKV infection. Passive transfer of immune sera did not result in significant cross-protection, but did mediate antibody dependent enhancement in vitro, though this did not have an adverse impact on survival. This study suggests that SA14-14-2 vaccine can protect against ZIKV through a cross-reactive T cell response. This is vital information in terms of ZIKV prevention or precaution in those ZIKV-affected regions where JEV circulates or SA14-14-2 is in widespread use, and opens a promising avenue into developing a novel bivalent vaccine against both ZIKV and JEV.ImportanceJapanese encephalitis is a controllable disease in many countries in Asia, especially in China, where many people have Japanese encephalitis virus (JEV) immunity due to extensive JEV vaccination campaigns or natural exposure. Live-attenuated SA14-14-2 strain is a safe and effective vaccine recommended by the World Health Organization and has been vaccinated more than 600 million doses since 1989. As the prevalence of Zika virus (ZIKV) and rising risk in above regions, the cross-reactive immune response between these two antigenically closely related flaviviruses, JEV and ZIKV, should also be fully recognized, which is presumed to be based on those ambiguous cross-reactive immunity between dengue virus and ZIKV. In this study, we found that JEV SA14-14-2 vaccine conferred cross-protection against ZIKV challenge in mice, which is mainly due to cellular immunity rather than neutralizing antibody response. However, specific protective components or cooperation between components warrant to be explored in subsequent experiments. In conclusion, this study can provide important evidence for those who live in JEV-endemic areas and are at risk for ZIKV infection.

scholarly journals NS5 from Dengue Virus Serotype 2 Can Adopt a Conformation Analogous to That of Its Zika Virus and Japanese Encephalitis Virus Homologues

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
Abbas El Sahili ◽  
Tingjin Sherryl Soh ◽  
Jonas Schiltz ◽  
Aïcha Gharbi-Ayachi ◽  
Cheah Chen Seh ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Zika Virus ◽  
Nonstructural Protein ◽  
Vaccine Design ◽  
Encephalitis Virus ◽  
Virus Serotype ◽  
In Cells

ABSTRACT Flavivirus nonstructural protein 5 (NS5) contains an N-terminal methyltransferase (MTase) domain and a C-terminal polymerase (RNA-dependent RNA polymerase [RdRp]) domain fused through a 9-amino-acid linker. While the individual NS5 domains are structurally conserved, in the full-length protein, their relative orientations fall into two classes: the NS5 proteins from Japanese encephalitis virus (JEV) and Zika virus (ZIKV) adopt one conformation, while the NS5 protein from dengue virus serotype 3 (DENV3) adopts another. Here, we report a crystallographic structure of NS5 from DENV2 in a conformation similar to the extended one seen in JEV and ZIKV NS5 crystal structures. Replacement of the DENV2 NS5 linker with DENV1, DENV3, DENV4, JEV, and ZIKV NS5 linkers had modest or minimal effects on in vitro DENV2 MTase and RdRp activities. Heterotypic DENV NS5 linkers attenuated DENV2 replicon growth in cells, while the JEV and ZIKV NS5 linkers abolished replication. Thus, the JEV and ZIKV linkers likely hindered essential DENV2 NS5 interactions with other viral or host proteins within the virus replicative complex. Overall, this work sheds light on the dynamics of the multifunctional flavivirus NS5 protein and its interdomain linker. Targeting the NS5 linker is a possible strategy for producing attenuated flavivirus strains for vaccine design. IMPORTANCE Flaviviruses include important human pathogens, such as dengue virus and Zika virus. NS5 is a nonstructural protein essential for flavivirus RNA replication with dual MTase and RdRp enzyme activities and thus constitutes a major drug target. Insights into NS5 structure, dynamics, and evolution should inform the development of antiviral inhibitors and vaccine design. We found that NS5 from DENV2 can adopt a conformation resembling that of NS5 from JEV and ZIKV. Replacement of the DENV2 NS5 linker with the JEV and ZIKV NS5 linkers abolished DENV2 replication in cells, without significantly impacting in vitro DENV2 NS5 enzymatic activities. We propose that heterotypic flavivirus NS5 linkers impede DENV2 NS5 protein-protein interactions that are essential for virus replication.

scholarly journals The Involvement of Microglial Cells in Japanese Encephalitis Infections

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Thananya Thongtan ◽  
Chutima Thepparit ◽  
Duncan R. Smith
Keyword(s):  
Immune Responses ◽  
Japanese Encephalitis Virus ◽  
Japanese Encephalitis ◽  
Encephalitis Virus ◽  
Microglial Cells ◽  
Asian Countries ◽  
Adaptive Immune Responses ◽  
Neurological Sequelae ◽  
Adaptive Immune ◽  
Human Infections

Despite the availability of effective vaccines, Japanese encephalitis virus (JEV) infections remain a leading cause of encephalitis in many Asian countries. The virus is transmitted to humans byCulexmosquitoes, and, while the majority of human infections are asymptomatic, up to 30% of JE cases admitted to hospital die and 50% of the survivors suffer from neurological sequelae. Microglia are brain-resident macrophages that play key roles in both the innate and adaptive immune responses in the CNS and are thus of importance in determining the pathology of encephalitis as a result of JEV infection.

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