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Virus Research Jul 2023Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic virus that can cause severe viral encephalitis. Initial interactions between JEV and host cells are... (Review)
Review
Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic virus that can cause severe viral encephalitis. Initial interactions between JEV and host cells are required for productive viral infection and initiation of the viral life cycle. The elucidation of these interactions is critical, not only to understand the pathogenesis of JEV infection, but also to design efficient antiviral strategies. In this review, we outline the known viral and cellular components involved in JEV entry into host cells, with a particular focus on the initial virus-host cell interaction on the cell surface and the downstream early events such as endocytosis, membrane fusion, and viral genome release.
Topics: Animals; Humans; Encephalitis Virus, Japanese; Host Microbial Interactions; Virus Internalization; Encephalitis, Japanese; Endocytosis; Encephalitis Viruses, Japanese; Virus Replication
PubMed: 37086856
DOI: 10.1016/j.virusres.2023.199120 -
The Journal of Veterinary Medical... Mar 2019Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus within the family Flaviviridae, causes fatal encephalitis with severe sequelae in humans. TBEV is... (Review)
Review
Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus within the family Flaviviridae, causes fatal encephalitis with severe sequelae in humans. TBEV is prevalent over a wide area of the Eurasian continent including Europe, Russia, Far-Eastern Asia, and Japan. While it was previously thought that TBEV was not endemic in Japan, the first confirmed case of serologically diagnosed TBE was reported in 1993 in the southern area of Hokkaido Prefecture, Japan. In addition, TBEV has been isolated from dogs, wild rodents and ticks in the area. Our epizootiological survey indicated that endemic foci of TBEV were maintained in Hokkaido and other areas of Honshu. TBEV can be divided into three subtypes based on phylogenetic analyses. The Japanese isolates were classified as the Far Eastern subtype, which causes severe neural disorders with a higher mortality rate up to 30%. However, how viral replication and pathogenicity contribute to the neurological manifestations remains unclear. Recent studies have revealed distinctive mechanisms of TBEV pathogenicity and viral genetic factors associated with virulence. This review discusses the recent findings regarding the epidemiology and pathogenesis of TBEV.
Topics: Animals; Encephalitis Viruses, Tick-Borne; Encephalitis, Tick-Borne; Humans; Japan
PubMed: 30674746
DOI: 10.1292/jvms.18-0373 -
Flavivirus NS1 Triggers Tissue-Specific Vascular Endothelial Dysfunction Reflecting Disease Tropism.Cell Reports Feb 2019Flaviviruses cause systemic or neurotropic-encephalitic pathology in humans. The flavivirus nonstructural protein 1 (NS1) is a secreted glycoprotein involved in viral...
Flaviviruses cause systemic or neurotropic-encephalitic pathology in humans. The flavivirus nonstructural protein 1 (NS1) is a secreted glycoprotein involved in viral replication, immune evasion, and vascular leakage during dengue virus infection. However, the contribution of secreted NS1 from related flaviviruses to viral pathogenesis remains unknown. Here, we demonstrate that NS1 from dengue, Zika, West Nile, Japanese encephalitis, and yellow fever viruses selectively binds to and alters permeability of human endothelial cells from lung, dermis, umbilical vein, brain, and liver in vitro and causes tissue-specific vascular leakage in mice, reflecting the pathophysiology of each flavivirus. Mechanistically, each flavivirus NS1 leads to differential disruption of endothelial glycocalyx components, resulting in endothelial hyperpermeability. Our findings reveal the capacity of a secreted viral protein to modulate endothelial barrier function in a tissue-specific manner both in vitro and in vivo, potentially influencing virus dissemination and pathogenesis and providing targets for antiviral therapies and vaccine development.
Topics: Animals; Brain; Cell Line; Cell Membrane Permeability; Dengue; Dengue Virus; Dermis; Encephalitis Virus, Japanese; Endothelial Cells; Gene Expression; Glycocalyx; Humans; Liver; Lung; Male; Mice; Organ Specificity; Primary Cell Culture; Umbilical Veins; Viral Nonstructural Proteins; Virus Replication; West Nile virus; Yellow fever virus; Zika Virus
PubMed: 30726741
DOI: 10.1016/j.celrep.2019.01.036 -
Infectious Disease Clinics of North... Sep 2022Powassan virus is an increasingly recognized cause of severe encephalitis that is transmitted by Ixodes ticks. Given the nonspecific clinical, laboratory, and imaging... (Review)
Review
Powassan virus is an increasingly recognized cause of severe encephalitis that is transmitted by Ixodes ticks. Given the nonspecific clinical, laboratory, and imaging features of Powassan virus disease, providers should consider it in patients with compatible exposures and request appropriate testing.
Topics: Encephalitis Viruses, Tick-Borne; Encephalitis, Tick-Borne; Humans
PubMed: 36116842
DOI: 10.1016/j.idc.2022.03.003 -
Revue Scientifique Et Technique... Aug 2015Tick-borne encephalitis (TBE), a zoonotic arbovirosis caused by tick-borne encephalitis virus (TBEV), is an increasing public health concern. Infections result in... (Review)
Review
Tick-borne encephalitis (TBE), a zoonotic arbovirosis caused by tick-borne encephalitis virus (TBEV), is an increasing public health concern. Infections result in neurological symptoms in humans and the virus has rapidly expanded to new geographical areas. Three subtypes are currently present in different parts of Europe and Asia. The virus is transmitted by ticks, mainly Ixodes spp., between small mammals such as rodents, which serve as virus amplifying hosts. Humans are infected sporadically, either by a tick bite or by ingestion of infected milk or milk products. Other mammals (e.g. ruminants) can also be infected, but most of the time do not show clinical signs. In contrast to rodents, other wild and domestic mammals probably play only a very small direct role in maintaining TBEV in an area, but they might play an important role as hosts in sustaining a large tick population. Therefore, the virus prevalence and the occurrence of TBE can be influenced by several environmental, genetic and behavioural factors associated with the virus, the vectors or the hosts, and understanding these factors is essential for implementation of effective control measures. This article reviews virus characteristics and the epidemiological and clinical aspects of TBEV infections and examines pathogenesis, diagnostic approaches and control measures.
Topics: Animals; Encephalitis Viruses, Tick-Borne; Encephalitis, Tick-Borne; Genetic Variation; Humans; Phylogeny
PubMed: 26601448
DOI: 10.20506/rst.34.2.2371 -
Frontiers in Cellular and Infection... 2022The genus is made up of viruses that are either mosquito-borne or tick-borne and other viruses transmitted by unknown vectors. Flaviviruses present a significant threat... (Review)
Review
The genus is made up of viruses that are either mosquito-borne or tick-borne and other viruses transmitted by unknown vectors. Flaviviruses present a significant threat to global health and infect up to 400 million of people annually. As the climate continues to change throughout the world, these viruses have become prominent infections, with increasing number of infections being detected beyond tropical borders. These include dengue virus (DENV), West Nile virus (WNV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV). Several highly conserved epitopes of flaviviruses had been identified and reported to interact with antibodies, which lead to cross-reactivity results. The major interest of this review paper is mainly focused on the serological cross-reactivity between DENV serotypes, ZIKV, WNV, and JEV. Direct and molecular techniques are required in the diagnosis of -associated human disease. In this review, the serological assays such as neutralization tests, enzyme-linked immunosorbent assay, hemagglutination-inhibition test, Western blot test, and immunofluorescence test will be discussed. Serological assays that have been developed are able to detect different immunoglobulin isotypes (IgM, IgG, and IgA); however, it is challenging when interpreting the serological results due to the broad antigenic cross-reactivity of antibodies to these viruses. However, the neutralization tests are still considered as the gold standard to differentiate these flaviviruses.
Topics: Animals; Antibodies, Viral; Cross Reactions; Dengue Virus; Encephalitis Virus, Japanese; Enzyme-Linked Immunosorbent Assay; Epitopes; Flavivirus; Humans; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M; Mosquito Vectors; West Nile virus; Zika Virus; Zika Virus Infection
PubMed: 36189346
DOI: 10.3389/fcimb.2022.975398 -
Viruses Sep 2022The beginning decades of the 21st century have been marked by multiple emergence and re-emergence phenomena of viral diseases [...].
The beginning decades of the 21st century have been marked by multiple emergence and re-emergence phenomena of viral diseases [...].
Topics: Humans; Encephalitis Viruses, Tick-Borne; West Nile Fever; West Nile virus; Encephalitis, Tick-Borne; Antibodies, Viral
PubMed: 36298675
DOI: 10.3390/v14102120 -
Emerging Infectious Diseases Jan 2020During February 2018-January 2019, we conducted large-scale surveillance for the presence and prevalence of tick-borne encephalitis virus (TBEV) and louping ill virus...
During February 2018-January 2019, we conducted large-scale surveillance for the presence and prevalence of tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) in sentinel animals and ticks in the United Kingdom. Serum was collected from 1,309 deer culled across England and Scotland. Overall, 4% of samples were ELISA-positive for the TBEV serocomplex. A focus in the Thetford Forest area had the highest proportion (47.7%) of seropositive samples. Ticks collected from culled deer within seropositive regions were tested for viral RNA; 5 of 2,041 ticks tested positive by LIV/TBEV real-time reverse transcription PCR, all from within the Thetford Forest area. From 1 tick, we identified a full-length genomic sequence of TBEV. Thus, using deer as sentinels revealed a potential TBEV focus in the United Kingdom. This detection of TBEV genomic sequence in UK ticks has important public health implications, especially for undiagnosed encephalitis.
Topics: Animals; Deer; Encephalitis Viruses, Tick-Borne; Encephalitis, Tick-Borne; Enzyme-Linked Immunosorbent Assay; Female; Hemagglutination Inhibition Tests; Humans; Ixodidae; Male; Phylogeny; RNA, Viral; Reverse Transcriptase Polymerase Chain Reaction; Sentinel Species; Sequence Analysis, RNA; United Kingdom
PubMed: 31661056
DOI: 10.3201/eid2601.191085 -
Viruses Aug 2017Apoptosis is a type of programmed cell death that regulates cellular homeostasis by removing damaged or unnecessary cells. Its importance in host defenses is highlighted... (Review)
Review
Apoptosis is a type of programmed cell death that regulates cellular homeostasis by removing damaged or unnecessary cells. Its importance in host defenses is highlighted by the observation that many viruses evade, obstruct, or subvert apoptosis, thereby blunting the host immune response. Infection with Flaviviruses such as Japanese encephalitis virus (JEV), Dengue virus (DENV) and West Nile virus (WNV) has been shown to activate several signaling pathways such as endoplasmic reticulum (ER)-stress and AKT/PI3K pathway, resulting in activation or suppression of apoptosis in virus-infected cells. On the other hands, expression of some viral proteins induces or protects apoptosis. There is a discrepancy between induction and suppression of apoptosis during flavivirus infection because the experimental situation may be different, and strong links between apoptosis and other types of cell death such as necrosis may make it more difficult. In this paper, we review the effects of apoptosis on viral propagation and pathogenesis during infection with flaviviruses.
Topics: Animals; Apoptosis; Cell Death; Cell Survival; Dengue Virus; Encephalitis Virus, Japanese; Endoplasmic Reticulum; Flavivirus; Flavivirus Infections; Host-Pathogen Interactions; Humans; Life Cycle Stages; Lymphoma, B-Cell; Neoplasms; Phosphatidylinositol 3-Kinases; Signal Transduction; Stress, Physiological; West Nile virus
PubMed: 28846635
DOI: 10.3390/v9090243 -
Viruses Jun 2018Tick-borne encephalitis virus (TBEV) is a growing health concern. It causes a severe disease that can lead to permanent neurological complications or death and the... (Review)
Review
Tick-borne encephalitis virus (TBEV) is a growing health concern. It causes a severe disease that can lead to permanent neurological complications or death and the incidence of TBEV infections is constantly rising. Our understanding of TBEV’s structure lags behind that of other flaviviruses, but has advanced recently with the publication of a high-resolution structure of the TBEV virion. The gaps in our knowledge include: aspects of receptor binding, replication and virus assembly. Furthermore, TBEV has mostly been studied in mammalian systems, even though the virus’ interaction with its tick hosts is a central part of its life cycle. Elucidating these aspects of TBEV biology are crucial for the development of TBEV antivirals, as well as the improvement of diagnostics. In this review, we summarise the current structural knowledge on TBEV, bringing attention to the current gaps in our understanding, and propose further research that is needed to truly understand the structural-functional relationship of the virus and its hosts.
Topics: Animals; Encephalitis Viruses, Tick-Borne; Encephalitis, Tick-Borne; Genome, Viral; Genomics; Humans; Life Cycle Stages; Structure-Activity Relationship; Viral Proteins; Virus Replication
PubMed: 29958443
DOI: 10.3390/v10070350