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Zeitschriftenartikel zum Thema "Flavivirus – Transmission"
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Zhang, Xianwen, Yuhan Li, Yingyi Cao, Ying Wu und Gong Cheng. „The Role of Noncoding RNA in the Transmission and Pathogenicity of Flaviviruses“. Viruses 16, Nr. 2 (02.02.2024): 242. http://dx.doi.org/10.3390/v16020242.
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Noncoding RNAs (ncRNAs) constitute a class of RNA molecules that lack protein-coding capacity. ncRNAs frequently modulate gene expression through specific interactions with target proteins or messenger RNAs, thereby playing integral roles in a wide array of cellular processes. The Flavivirus genus comprises several significant members, such as dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV), which have caused global outbreaks, resulting in high morbidity and mortality in human populations. The life cycle of arthropod-borne flaviviruses encompasses their transmission between hematophagous insect vectors and mammalian hosts. During this process, a complex three-way interplay occurs among the pathogen, vector, and host, with ncRNAs exerting a critical regulatory influence. ncRNAs not only constitute a crucial regulatory mechanism that has emerged from the coevolution of viruses and their hosts but also hold potential as antiviral targets for controlling flavivirus epidemics. This review introduces the biogenesis of flavivirus-derived ncRNAs and summarizes the regulatory roles of ncRNAs in viral replication, vector-mediated viral transmission, antiviral innate immunity, and viral pathogenicity. A profound comprehension of the interplay between ncRNAs and flaviviruses will help formulate efficacious prophylactic and therapeutic strategies against flavivirus-related diseases.
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Habarugira, Gervais, Jasmin Moran, Jessica J. Harrison, Sally R. Isberg, Jody Hobson-Peters, Roy A. Hall und Helle Bielefeldt-Ohmann. „Evidence of Infection with Zoonotic Mosquito-Borne Flaviviruses in Saltwater Crocodiles (Crocodylus porosus) in Northern Australia“. Viruses 14, Nr. 5 (21.05.2022): 1106. http://dx.doi.org/10.3390/v14051106.
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The risk of flavivirus infections among the crocodilian species was not recognised until West Nile virus (WNV) was introduced into the Americas. The first outbreaks caused death and substantial economic losses in the alligator farming industry. Several other WNV disease episodes have been reported in crocodilians in other parts of the world, including Australia and Africa. Considering that WNV shares vectors with other flaviviruses, crocodilians are highly likely to also be exposed to flaviviruses other than WNV. A serological survey for flaviviral infections was conducted on saltwater crocodiles (Crocodylus porosus) at farms in the Northern Territory, Australia. Five hundred serum samples, collected from three crocodile farms, were screened using a pan-flavivirus-specific blocking ELISA. The screening revealed that 26% (n = 130/500) of the animals had antibodies to flaviviruses. Of these, 31.5% had neutralising antibodies to WNVKUN (Kunjin strain), while 1.5% had neutralising antibodies to another important flavivirus pathogen, Murray Valley encephalitis virus (MVEV). Of the other flaviviruses tested for, Fitzroy River virus (FRV) was the most frequent (58.5%) in which virus neutralising antibodies were detected. Our data indicate that farmed crocodiles in the Northern Territory are exposed to a range of potentially zoonotic flaviviruses, in addition to WNVKUN. While these flaviviruses do not cause any known diseases in crocodiles, there is a need to investigate whether infected saltwater crocodiles can develop a viremia to sustain the transmission cycle or farmed crocodilians can be used as sentinels to monitor the dynamics of arboviral infections in tropical areas.
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Göertz, G. P., J. J. Fros, P. Miesen, C. B. F. Vogels, M. L. van der Bent, C. Geertsema, C. J. M. Koenraadt, R. P. van Rij, M. M. van Oers und G. P. Pijlman. „Noncoding Subgenomic Flavivirus RNA Is Processed by the Mosquito RNA Interference Machinery and Determines West Nile Virus Transmission by Culex pipiens Mosquitoes“. Journal of Virology 90, Nr. 22 (31.08.2016): 10145–59. http://dx.doi.org/10.1128/jvi.00930-16.
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ABSTRACT Flaviviruses, such as Zika virus, yellow fever virus, dengue virus, and West Nile virus (WNV), are a serious concern for human health. Flaviviruses produce an abundant noncoding subgenomic flavivirus RNA (sfRNA) in infected cells. sfRNA results from stalling of the host 5′-3′ exoribonuclease XRN1/Pacman on conserved RNA structures in the 3′ untranslated region (UTR) of the viral genomic RNA. sfRNA production is conserved in insect-specific, mosquito-borne, and tick-borne flaviviruses and flaviviruses with no known vector, suggesting a pivotal role for sfRNA in the flavivirus life cycle. Here, we investigated the function of sfRNA during WNV infection of Culex pipiens mosquitoes and evaluated its role in determining vector competence. An sfRNA1-deficient WNV was generated that displayed growth kinetics similar to those of wild-type WNV in both RNA interference (RNAi)-competent and -compromised mosquito cell lines. Small-RNA deep sequencing of WNV-infected mosquitoes indicated an active small interfering RNA (siRNA)-based antiviral response for both the wild-type and sfRNA1-deficient viruses. Additionally, we provide the first evidence that sfRNA is an RNAi substrate in vivo . Two reproducible small-RNA hot spots within the 3′ UTR/sfRNA of the wild-type virus mapped to RNA stem-loops SL-III and 3′ SL, which stick out of the three-dimensional (3D) sfRNA structure model. Importantly, we demonstrate that sfRNA-deficient WNV displays significantly decreased infection and transmission rates in vivo when administered via the blood meal. Finally, we show that transmission and infection rates are not affected by sfRNA after intrathoracic injection, thereby identifying sfRNA as a key driver to overcome the mosquito midgut infection barrier. This is the first report to describe a key biological function of sfRNA for flavivirus infection of the arthropod vector, providing an explanation for the strict conservation of sfRNA production. IMPORTANCE Understanding the flavivirus transmission cycle is important to identify novel targets to interfere with disease and to aid development of virus control strategies. Flaviviruses produce an abundant noncoding viral RNA called sfRNA in both arthropod and mammalian cells. To evaluate the role of sfRNA in flavivirus transmission, we infected mosquitoes with the flavivirus West Nile virus and an sfRNA-deficient mutant West Nile virus. We demonstrate that sfRNA determines the infection and transmission rates of West Nile virus in Culex pipiens mosquitoes. Comparison of infection via the blood meal versus intrathoracic injection, which bypasses the midgut, revealed that sfRNA is important to overcome the mosquito midgut barrier. We also show that sfRNA is processed by the antiviral RNA interference machinery in mosquitoes. This is the first report to describe a pivotal biological function of sfRNA in arthropods. The results explain why sfRNA production is evolutionarily conserved.
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Cook, Shelley, Shannon N. Bennett, Edward C. Holmes, Reine De Chesse, Gregory Moureau und Xavier de Lamballerie. „Isolation of a new strain of the flavivirus cell fusing agent virus in a natural mosquito population from Puerto Rico“. Journal of General Virology 87, Nr. 4 (01.04.2006): 735–48. http://dx.doi.org/10.1099/vir.0.81475-0.
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The genus Flavivirus contains approximately 70 single-stranded, positive-sense RNA viruses that are mosquito-borne, tick-borne or have no known vector. Two discoveries support previous suggestions of the existence of a large number of unsampled flaviviruses: (i) a new flavivirus, Kamiti River virus, was recently isolated from Kenyan mosquitoes, and (ii) sequences with high similarity to those of flaviviruses have been found integrated into the genome of Aedes mosquitoes, suggesting a past infection with a virus (or viruses) that has yet to be discovered. These sequences were related most closely to a flavivirus that infects insects alone, cell fusing agent virus (CFAV). CFAV was originally isolated in the laboratory from an Aedes aegypti cell line. To date, this virus had not been found in the wild. In the present study, over 40 isolates of a novel strain of CFAV were discovered from mature mosquitoes sampled from the wild in Puerto Rico. The viral strain was present in a range of mosquito species, including Aedes aegypti, Aedes albopictus and Culex sp., from numerous locations across the island and, importantly, in mosquitoes of both sexes, suggesting vertical transmission. Here, results from viral screening, and cell culture and molecular identification of the infected mosquitoes are presented. Experimental-infection tests were also conducted by using the original CFAV strain and a highly efficient reverse-transcription mechanism has been documented, in which initiation of copying occurs at the 3′ terminus of either the genomic RNA or the intermediate of replication, potentially elucidating the mechanism by which flaviviral sequences may have integrated into mosquito genomes.
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Vasilakis, Nikos, und Scott C. Weaver. „Flavivirus transmission focusing on Zika“. Current Opinion in Virology 22 (Februar 2017): 30–35. http://dx.doi.org/10.1016/j.coviro.2016.11.007.
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Wang, Hong-Jiang, Xiao-Feng Li, Long Liu, Yan-Peng Xu, Qing Ye, Yong-Qiang Deng, Xing-Yao Huang et al. „The Emerging Duck Flavivirus Is Not Pathogenic for Primates and Is Highly Sensitive to Mammalian Interferon Antiviral Signaling“. Journal of Virology 90, Nr. 14 (04.05.2016): 6538–48. http://dx.doi.org/10.1128/jvi.00197-16.
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ABSTRACTFlaviviruses pose a significant threat to both animals and humans. Recently, a novel flavivirus, duck Tembusu virus (DTMUV), was identified to be the causative agent of a serious duck viral disease in Asia. Its rapid spread, expanding host range, and uncertain transmission routes have raised substantial concerns regarding its potential threats to nonavian hosts, including humans. Here, we demonstrate that DTMUV is not pathogenic for nonhuman primates and is highly sensitive to mammal type I interferon (IFN) signaling.In vitroassays demonstrated that DTMUV infected and replicated efficiently in various mammalian cell lines. Further tests in mice demonstrated high neurovirulence and the age-dependent neuroinvasiveness of the virus. In particular, the inoculation of DTMUV into rhesus monkeys did not result in either viremia or apparent clinical symptoms, although DTMUV-specific humoral immune responses were detected. Furthermore, we revealed that although avian IFN failed to inhibit DTMUV in avian cells, DTMUV was more sensitive to the antiviral effects of type I interferon than other known human-pathogenic flaviviruses. Knockout of the type I IFN receptor in mice caused apparent viremia, viscerotropic disease, and mortality, indicating a vital role of IFN signaling in protection against DTMUV infection. Collectively, we provide direct experimental evidence that this novel avian-origin DTMUV possesses a limited capability to establish infection in immunocompetent primates due to its decreased antagonistic activity in the mammal IFN system. Furthermore, our findings highlight the potential risk of DTMUV infection in immunocompromised individuals and warrant studies on the cross-species transmission and pathogenesis of this novel flavivirus.IMPORTANCEMosquito-borne flaviviruses comprise a large group of pathogenic and nonpathogenic members. The pathogenic flaviviruses include dengue, West Nile, and Japanese encephalitis viruses, and the nonpathogenic flaviviruses normally persist in a natural cycle and rarely cause disease in humans. A novel flavivirus, DTMUV (also known as duck egg drop syndrome flavivirus [DEDSV]) was identified in 2012 in ducks and then rapidly spread to several Asian countries. This new flavivirus was then shown to infect multiple avian species, resulting in neurological symptoms with unknown routes of transmission. There is public concern regarding its potential transmission from birds to humans and other nonavian hosts. Our present study shows that the mammalian IFN system can efficiently eliminate DTMUV infection and that the emergence of severe DTMUV-associated disease in mammals, especially humans, is unlikely. Currently, DTMUV infection mostly affects avian species.
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Göertz, Giel P., Joyce W. M. van Bree, Anwar Hiralal, Bas M. Fernhout, Carmen Steffens, Sjef Boeren, Tessa M. Visser et al. „Subgenomic flavivirus RNA binds the mosquito DEAD/H-box helicase ME31B and determines Zika virus transmission by Aedes aegypti“. Proceedings of the National Academy of Sciences 116, Nr. 38 (05.09.2019): 19136–44. http://dx.doi.org/10.1073/pnas.1905617116.
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Zika virus (ZIKV) is an arthropod-borne flavivirus predominantly transmitted by Aedes aegypti mosquitoes and poses a global human health threat. All flaviviruses, including those that exclusively replicate in mosquitoes, produce a highly abundant, noncoding subgenomic flavivirus RNA (sfRNA) in infected cells, which implies an important function of sfRNA during mosquito infection. Currently, the role of sfRNA in flavivirus transmission by mosquitoes is not well understood. Here, we demonstrate that an sfRNA-deficient ZIKV (ZIKVΔSF1) replicates similar to wild-type ZIKV in mosquito cell culture but is severely attenuated in transmission by Ae. aegypti after an infectious blood meal, with 5% saliva-positive mosquitoes for ZIKVΔSF1 vs. 31% for ZIKV. Furthermore, viral titers in the mosquito saliva were lower for ZIKVΔSF1 as compared to ZIKV. Comparison of mosquito infection via infectious blood meals and intrathoracic injections showed that sfRNA is important for ZIKV to overcome the mosquito midgut barrier and to promote virus accumulation in the saliva. Next-generation sequencing of infected mosquitoes showed that viral small-interfering RNAs were elevated upon ZIKVΔSF1 as compared to ZIKV infection. RNA-affinity purification followed by mass spectrometry analysis uncovered that sfRNA specifically interacts with a specific set of Ae. aegypti proteins that are normally associated with RNA turnover and protein translation. The DEAD/H-box helicase ME31B showed the highest affinity for sfRNA and displayed antiviral activity against ZIKV in Ae. aegypti cells. Based on these results, we present a mechanistic model in which sfRNA sequesters ME31B to promote flavivirus replication and virion production to facilitate transmission by mosquitoes.
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AYADI, T., A. HAMMOUDA, A. POUX, T. BOULINIER, S. LECOLLINET und S. SELMI. „Evidence of exposure of laughing doves (Spilopelia senegalensis) to West Nile and Usutu viruses in southern Tunisian oases“. Epidemiology and Infection 145, Nr. 13 (14.08.2017): 2808–16. http://dx.doi.org/10.1017/s0950268817001789.
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SUMMARYIt has previously been suggested that southern Tunisian oases may be suitable areas for the circulation of flaviviruses. In order to anticipate and prevent possible epidemiological spread of flaviviruses in humans and domestic animals, the ecology of their transmission in the oasis system needs to be better understood. Thus, the aim of this study was to assess the seroprevalence of anti-flavivirus antibodies in the laughing dove (Spilopelia senegalensis), an abundant resident bird in Tunisian oases. Anti-flavivirus antibodies were detected in 17% of sampled doves. Ten per cent of the total tested doves were West Nile virus (WNV) seropositive and 4% were Usutu virus (USUV) seropositive, which provides the first evidence of USUV circulation in Tunisian birds. We also found that the occurrence probability of anti-flavivirus antibodies in dove plasma increased with decreasing distance to coast, suggesting that doves inhabiting coastal oases were more exposed to flaviviruses compared with those inhabiting inland oases. We also found significantly higher antibody occurrence probability in adult doves compared with young doves, which underlines the effect of exposure time. Overall, our results suggest that the laughing dove may be used for WNV and USUV surveillance in southern Tunisia. They also stress the need for investigations combining data on birds and mosquitoes to better understand the ecological factors governing the circulation of flaviviruses in this area.
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Williams, Richard A. J., Hillary A. Criollo Valencia, Irene López Márquez, Fernando González González, Francisco Llorente, Miguel Ángel Jiménez-Clavero, Núria Busquets, Marta Mateo Barrientos, Gustavo Ortiz-Díez und Tania Ayllón Santiago. „West Nile Virus Seroprevalence in Wild Birds and Equines in Madrid Province, Spain“. Veterinary Sciences 11, Nr. 6 (07.06.2024): 259. http://dx.doi.org/10.3390/vetsci11060259.
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West Nile virus (WNV) is a re-emerging flavivirus, primarily circulating among avian hosts and mosquito vectors, causing periodic outbreaks in humans and horses, often leading to neuroinvasive disease and mortality. Spain has reported several outbreaks, most notably in 2020 with seventy-seven human cases and eight fatalities. WNV has been serologically detected in horses in the Community of Madrid, but to our knowledge, it has never been reported from wild birds in this region. To estimate the seroprevalence of WNV in wild birds and horses in the Community of Madrid, 159 wild birds at a wildlife rescue center and 25 privately owned equines were sampled. Serum from thirteen birds (8.2%) and one equine (4.0%) tested positive with a WNV competitive enzyme-linked immunosorbent assay (cELISA) designed for WNV antibody detection but sensitive to cross-reacting antibodies to other flaviviruses. Virus-neutralization test (VNT) confirmed WNV antibodies in four bird samples (2.5%), and antibodies to undetermined flavivirus in four additional samples. One equine sample (4.0%) tested positive for WNV by VNT, although this horse previously resided in a WN-endemic area. ELISA-positive birds included both migratory and resident species, juveniles and adults. Two seropositive juvenile birds suggest local flavivirus transmission within the Community of Madrid, while WNV seropositive adult birds may have been infected outside Madrid. The potential circulation of flaviviruses, including WNV, in birds in the Madrid Community raises concerns, although further surveillance of mosquitoes, wild birds, and horses in Madrid is necessary to establish the extent of transmission and the principal species involved.
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Reyes-Ruiz, José Manuel, Juan Fidel Osuna-Ramos, Luis Adrián De Jesús-González, Selvin Noé Palacios-Rápalo, Carlos Daniel Cordero-Rivera, Carlos Noe Farfan-Morales, Arianna Mahely Hurtado-Monzón et al. „The Regulation of Flavivirus Infection by Hijacking Exosome-Mediated Cell–Cell Communication: New Insights on Virus–Host Interactions“. Viruses 12, Nr. 7 (16.07.2020): 765. http://dx.doi.org/10.3390/v12070765.
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The arthropod-borne flaviviruses are important human pathogens, and a deeper understanding of the virus–host cell interaction is required to identify cellular targets that can be used as therapeutic candidates. It is well reported that the flaviviruses hijack several cellular functions, such as exosome-mediated cell communication during infection, which is modulated by the delivery of the exosomal cargo of pro- or antiviral molecules to the receiving host cells. Therefore, to study the role of exosomes during flavivirus infections is essential, not only to understand its relevance in virus–host interaction, but also to identify molecular factors that may contribute to the development of new strategies to block these viral infections. This review explores the implications of exosomes in flavivirus dissemination and transmission from the vector to human host cells, as well as their involvement in the host immune response. The hypothesis about exosomes as a transplacental infection route of ZIKV and the paradox effect or the dual role of exosomes released during flavivirus infection are also discussed here. Although several studies have been performed in order to identify and characterize cellular and viral molecules released in exosomes, it is not clear how all of these components participate in viral pathogenesis. Further studies will determine the balance between protective and harmful exosomes secreted by flavivirus infected cells, the characteristics and components that distinguish them both, and how they could be a factor that determines the infection outcome.
Dissertationen zum Thema "Flavivirus – Transmission"
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Lequime, Sébastian. „Interactions flavivirus-moustiques : diversité et transmission“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066081/document.
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Les flavivirus sont des virus à ARN parmi lesquels certains sont des arbovirus transmis entre hôtes vertébrés par des vecteurs arthropodes, notamment des moustiques. L'interaction avec les moustiques est centrale dans la biologie des flavivirus par son influence sur leur diversité génétique et transmission, mais certains de ses aspects restent méconnus. Au cœur de cette thèse, des approches basées sur les « big data », générées par des technologies modernes ou par compilation de travaux plus anciens, ont éclairé d’un jour nouveau la complexité des relations moustique-flavivirus. En explorant des génomes de moustiques anophèles, nous avons identifié et caractérisé des éléments viraux endogènes d'origine flavivirale chez Anopheles sinensis et An. minimus, suggérant l'existence de flavivirus infectant les anophèles et révélant une facette insoupçonnée de leur diversité. Par ailleurs, nous avons exploré, par séquençage haut-débit, la fine interaction entre le génotype du moustique Aedes aegypti et la diversité intra-hôte du virus de la dengue-1. Nos résultats montrent un fort effet de la dérive génétique lors de l'infection initiale, diminuant l'importance relative de la sélection naturelle, et une modulation de la diversité génétique intra-hôte du virus par le génotype du moustique. Enfin, nous avons compilé la littérature sur la transmission verticale des arbovirus chez les moustiques, c'est-à-dire de la femelle infectée à sa descendance, afin d'identifier des facteurs techniques et biologiques sous-jacents. Nos résultats améliorent la compréhension de ce mode de transmission et des stratégies employées par les arbovirus pour persister dans l’environnementFlaviviruses are RNA virus among which some are arboviruses transmitted between vertebrate hosts and arthropod vectors, like mosquitoes. The interaction with mosquitoes is key in the biology of flaviviruses because it influences their genetic diversity and transmission. However, some aspects however are still poorly understood. At the heart of the work presented in this dissertation, strategies based on ‘big data’, both by taking advantage of modern technologies and by compiling older literature, highlighted new aspects of the complex relationships between flaviviruses and mosquitoes. While exploring Anopheles mosquito genomes, we identified and characterized endogenous viral elements of flaviviral origin in Anopheles sinensis and An. minimus, which supports the existence of flaviviruses infecting Anopheles mosquitoes and highlights new aspected of their diversity. Besides, we explored, by deep sequencing, the fine-tuned interaction between genotypes of the mosquito Aedes aegypti and the intra-host diversity of dengue virus 1. Our results showed a strong effect of genetic drift during initial infection, reducing the relative importance of natural selection, and a modulation of the intra-host viral genetic diversity by the mosquito genotype. Finally, we assembled the litterature on arbovirus vertical transmission in the mosquito vector, i.e. from an infected female to her offspring, in order to identify underlying technical and biological predictors. Our results increase our understanding of this transmission mode and the strategies employed by arboviruses to persist in their environment
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Lequime, Sébastian. „Interactions flavivirus-moustiques : diversité et transmission“. Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066081.pdf.
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Les flavivirus sont des virus à ARN parmi lesquels certains sont des arbovirus transmis entre hôtes vertébrés par des vecteurs arthropodes, notamment des moustiques. L'interaction avec les moustiques est centrale dans la biologie des flavivirus par son influence sur leur diversité génétique et transmission, mais certains de ses aspects restent méconnus. Au cœur de cette thèse, des approches basées sur les « big data », générées par des technologies modernes ou par compilation de travaux plus anciens, ont éclairé d’un jour nouveau la complexité des relations moustique-flavivirus. En explorant des génomes de moustiques anophèles, nous avons identifié et caractérisé des éléments viraux endogènes d'origine flavivirale chez Anopheles sinensis et An. minimus, suggérant l'existence de flavivirus infectant les anophèles et révélant une facette insoupçonnée de leur diversité. Par ailleurs, nous avons exploré, par séquençage haut-débit, la fine interaction entre le génotype du moustique Aedes aegypti et la diversité intra-hôte du virus de la dengue-1. Nos résultats montrent un fort effet de la dérive génétique lors de l'infection initiale, diminuant l'importance relative de la sélection naturelle, et une modulation de la diversité génétique intra-hôte du virus par le génotype du moustique. Enfin, nous avons compilé la littérature sur la transmission verticale des arbovirus chez les moustiques, c'est-à-dire de la femelle infectée à sa descendance, afin d'identifier des facteurs techniques et biologiques sous-jacents. Nos résultats améliorent la compréhension de ce mode de transmission et des stratégies employées par les arbovirus pour persister dans l’environnementFlaviviruses are RNA virus among which some are arboviruses transmitted between vertebrate hosts and arthropod vectors, like mosquitoes. The interaction with mosquitoes is key in the biology of flaviviruses because it influences their genetic diversity and transmission. However, some aspects however are still poorly understood. At the heart of the work presented in this dissertation, strategies based on ‘big data’, both by taking advantage of modern technologies and by compiling older literature, highlighted new aspects of the complex relationships between flaviviruses and mosquitoes. While exploring Anopheles mosquito genomes, we identified and characterized endogenous viral elements of flaviviral origin in Anopheles sinensis and An. minimus, which supports the existence of flaviviruses infecting Anopheles mosquitoes and highlights new aspected of their diversity. Besides, we explored, by deep sequencing, the fine-tuned interaction between genotypes of the mosquito Aedes aegypti and the intra-host diversity of dengue virus 1. Our results showed a strong effect of genetic drift during initial infection, reducing the relative importance of natural selection, and a modulation of the intra-host viral genetic diversity by the mosquito genotype. Finally, we assembled the litterature on arbovirus vertical transmission in the mosquito vector, i.e. from an infected female to her offspring, in order to identify underlying technical and biological predictors. Our results increase our understanding of this transmission mode and the strategies employed by arboviruses to persist in their environment
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Terrien, Vincent Alliot Anne. „Les culicidés transmission vectorielle des infections et parasitoses à l'homme /“. [S.l.] : [s.n.], 2008. http://castore.univ-nantes.fr/castore/GetOAIRef?idDoc=46631.
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Couderc, Élodie. „Discovery of mosquito molecular factors modulating arbovirus infection in Aedes aegypti“. Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS199.
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Les virus transmis par les arthropodes (arbovirus) impactent significativement la santé humaine à l'échelle mondiale, causant des maladies avec une morbidité et une mortalité élevées. Les flavivirus transmis par les moustiques, notamment les virus de la dengue (DENV) et Zika (ZIKV), sont particulièrement préoccupants. Ces virus sont principalement transmis par le moustique Aedes aegypti, dont la répartition géographique s'étend en raison des changements globaux. Actuellement, il n'existe pas de vaccins approuvés à grande échelle ni d'antiviraux spécifiques pour ces virus, et les méthodes traditionnelles de contrôle des vecteurs sont entravées par la résistance aux insecticides. Face à ces défis, des stratégies alternatives ont été développées pour manipuler la biologie des vecteurs afin de réduire leur compétence vectorielle, c'est-à-dire leur aptitude à être infectés et à transmettre des pathogènes. Une stratégie potentielle est de relâcher de moustiques modifiés incapables de transmettre des agents pathogènes. Il est donc crucial d'identifier des cibles optimales pour ces modifications, et les facteurs moléculaires des moustiques qui modulent la transmission des arbovirus sont des candidats prometteurs. Cependant, une grande partie des connaissances actuelles sur la compétence vectorielle des moustiques provient d'études sur l'insecte modèle Drosophila melanogaster, qui ne reproduit pas entièrement les réponses des moustiques. Des approches spécifiques aux moustiques sont donc essentielles pour étudier les facteurs intrinsèques de leur compétence vectorielle.Cette thèse de doctorat présente trois approches in vivo pour étudier les facteurs moléculaires influençant l'infection, la dissémination et la transmission des flavivirus chez Aedes aegypti. Le premier chapitre traite de la caractérisation fonctionnelle in vivo d'un gène Vago-like, VLG-1, chez Ae. aegypti dans le contexte de l'infection par les flavivirus. De façon surprenante, une lignée mutante de VLG-1 générée par CRISPR/Cas9 a montré que chez Ae. aegypti, VLG-1 favorise la dissémination de DENV et ZIKV dans le moustique, remettant en question le dogme affirmant que les gènes Vago-like sont des facteurs antiviraux conservés chez les arthropodes. Une analyse transcriptomique organe-spécifique a révélé que VLG-1 affecte des processus biologiques potentiellement liés à la réplication virale, tels que la réponse au stress oxydatif. Le deuxième chapitre rapporte la découverte d'un nouveau facteur antiviral non canonique, le cytochrome P450 4g15, associé à une résistance naturelle à DENV dans une population d'Ae. aegypti. L'induction de ce gène dans le tube digestif après un repas sanguin entrave l'infection par DENV. Des polymorphismes dans la séquence promotrice de ce gène contrôlent son expression et la probabilité d'infection par DENV. Cette étude est la première à démontrer l'impact de variants naturels d'un gène sur la résistance d'Ae. aegypti à DENV. Le troisième chapitre décrit la caractérisation in vivo de potentiels récepteurs de DENV chez Ae. aegypti, en particulier prohibitin-2. Malgré un effet proviral de prohibitin-2 sur la réplication de DENV dans le corps du moustique, ce gène n'a pas montré de rôle significatif dans l'entrée de DENV dans le tube digestif du moustique in vivo. Ces résultats indiquent que l'identification in vitro de récepteurs viraux ne garantit pas la confirmation in vivo de leur rôle dans l'entrée virale. En résumé, cette thèse de doctorat contribue à faire avancer notre compréhension des interactions moustiques-virus, à identifier de nouvelles cibles pour le contrôle des vecteurs et à mettre en lumière la complexité des mécanismes moléculaires de la compétence vectorielle. Elle met en avant la nécessité de la recherche in vivo et l'importance d'exploiter la diversité génétique naturelle des populations de moustiques pour développer des stratégies innovantes de contrôle des maladies transmises par les moustiquesArthropod-borne viruses (arboviruses) significantly impact global health, causing diseases with high morbidity and mortality. Mosquito-borne flaviviruses, notably dengue (DENV) and Zika (ZIKV) viruses, are of particular concern. These viruses are primarily transmitted by the Aedes aegypti mosquito, which is expanding its range due to global changes. Currently, there are no globally approved vaccines or specific antivirals for these viruses, and traditional vector control methods are hindered by insecticide resistance. Concerns about the future of vector control have led to alternative strategies aimed at manipulating the biology of vectors to reduce their vector competence, i.e., the ability of mosquitoes to become infected and transmit pathogens. The release of modified mosquitoes that cannot transmit pathogens is a potential strategy to reduce the incidence of human disease. Thus, there is a growing need to identify optimal targets for modification, and mosquito molecular factors that modulate arbovirus transmission are promising candidates.However, much of the knowledge on mosquito vector competence derives from studies in the insect model Drosophila melanogaster and does not fully recapitulate mosquito responses. Therefore, implementation of mosquito-specific approaches is essential to investigate intrinsic factors underlying vector competence. In this context, this PhD thesis presents three in vivo approaches to investigate molecular factors that influence flavivirus infection, dissemination, and transmission in Aedes aegypti.The first chapter is dedicated to the functional characterization of a Vago-like gene, VLG-1, in Ae. aegypti in the context of flavivirus infection. Arthropod Vago genes are often described as analogs of mammalian cytokines with antiviral functions. Strikingly, a VLG-1 mutant line generated by CRISPR/Cas9-mediated gene editing revealed that in Ae. aegypti, VLG-1 promotes DENV and ZIKV dissemination within the mosquito, challenging the idea that Vago-like genes are conserved antiviral factors. Tissue-specific transcriptome analysis indicated that VLG-1 affects biological processes potentially linked to viral replication, such as oxidative stress response. The second chapter focuses on the discovery of a novel non-canonical antiviral factor, cytochrome P450 4g15, associated with a natural DENV resistance phenotype in a field-derived Ae. aegypti population. Induction of cytochrome P450 4g15 in the midgut after bloodmeal ingestion hinders DENV infection. Polymorphisms in this gene's promoter sequence control its expression level and the probability of successful DENV infection, marking the first report of natural gene variants impacting DENV resistance in Ae. aegypti.The third chapter examines candidate DENV receptors in Ae. aegypti, with a specific emphasis on prohibitin-2. This study demonstrated a proviral effect of prohibitin-2 on DENV replication in mosquito bodies. Nevertheless, despite employing a range of experimental techniques, prohibitin-2 did not exhibit a substantial role in DENV entry into mosquito midguts in vivo. These findings indicate that in vitro identification of viral receptors may not necessarily translate to in vivo confirmation of their role in viral entry.Overall, this PhD thesis contributes to advancing our understanding of mosquito-virus interactions, identifying new targets for vector control strategies, and highlighting the complexity of the molecular mechanisms underlying vector competence. This work emphasizes the necessity for in vivo research and underscores the value of exploiting the natural genetic diversity of field-derived mosquito populations to gain insights into the complex mechanisms governing mosquito vector competence for flaviviruses and to develop innovative strategies for controlling mosquito-borne diseases
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Mondini, Adriano. „Análise molecular, espacial e temporal da transmissão de dengue no município de São José do Rio Preto.SP“. Faculdade de Medicina de São José do Rio Preto, 2010. http://bdtd.famerp.br/handle/tede/90.
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Dengue belongs to the Flavivirus genus and is the most common arboviral infection worldwide. It can be caused by four antigenically different serotypes (DENV 1-4). These serotypes are transmitted mainly by the bite of Aedes aegypti mosquitoes. The vector is widely associated with human activity and the influence of organized social space favors the interaction among vector, virus and man, making populated areas sources of dengue dispersion. In this study, we performed a molecular, spatial and temporal study of DENV transmission through positive samples of blood and infected mosquitoes captured in São José do Rio Preto/SP in a period of four years. Material and Methods: Serum samples of patients presenting dengue like symptoms and pools of mosquitoes had their viral RNA extracted and were tested by Multiplex- RT-PCR with Flavivirus generic primers based on non-structural protein (NS5) in the first round, followed by Nested assays with species-specific primers for the identification of DENV 1-3, yellow fever virus, Saint Louis encephalitis virus (SLEV) among others. Positive samples were analyzed spatially and phylogenetically. Results and Discussion: We analyzed 613 blood samples for four years: 199 in 2006, 94 in 2007, 313 in 2008 and 10 in 2009. The positivity was high in 2006 and 2007, with 106 and 51 infected patients, respectively. The major dengue serotype circulating during the 2006 and 2007 epidemics was DENV-3 and few cases of DENV-2, which is an indication of its recent introduction in the municipality. We also reported the first outbreak of SLEV in Brazil in 2006. Among DENV patients in 2008, only seven were infected by DENV-3 and 90 were infected by DENV-2, suggesting the reemergence of this serotype. We detected the circulation of DENV-1 in two Abstract xxv patients in 2008 and in four patients in 2009. Nearly 1200 mosquitoes were captured from December 2007 to March 2008. We have captured 814 Aedes aegypti mosquitoes, which were divided in 463 pools. Only 3.67% of them were positive for DENV-3 and DENV-2. Pools containing only male mosquitoes were positive for DENV, indicating the presence of transovarial transmission. We obtained sequences from 82 patients among 174 blood samples. We were able to geo-code 46 sequences. The alignment generated a 399-nucleotide long dataset with 134 taxa. The phylogenetic analysis indicated that all samples were of DENV-3 and related to strains circulating on the isle of Martinique in 2000 2001. Sixty DENV-3 from São José do Rio Preto formed a monophyletic group (lineage 1), closely related to the remaining 22 isolates (lineage 2). We assumed that these lineages appeared before 2006 in different occasions. The possibility of inferring the spatio-temporal dynamics from genetic data has been generally little explored, and it may shed light on DENV circulation. The use of both geographic and temporally structured phylogenetic data provided a detailed view on the spread of at least two dengue viral strains in a populated urban area.
Dengue pertence ao gênero Flavivirus e é a infecção por arbovírus mais comum no mundo todo. Pode ser causada por quatro sorotipos antigenicamente distintos (DENV 1-4). Estes sorotipos são transmitidos pela picada do mosquito Aedes aegypti. O vetor está amplamente associado a atividade humana e a influencia do espaço urbano favorece a interação entre o vetor, o vírus e o homem, tornando áreas populosas, grandes centros de dispersão do dengue. Neste estudo, foi realizada um estudo molecular, espacial e temporal da transmissão de DENV através de amostras positivas de sangue e de mosquitos infectados capturados em São José do Rio Preto/SP, num período de quatro anos. Materiais e métodos: Soro de pacientes apresentando sintomas de dengue e pools de mosquitos tiveram seu RNA viral extraído e foram testados por Multiplex-RT-PCR, com primers genéricos de Flavivirus baseados na proteína não estrutural 5 (NS5) numa primeiro ciclo,seguida por ensaios Nested com primers específicos para DENV, para o vírus da febre amarela, para o vírus da encefalite de Saint Louis, entre outros. As amostras positivas foram analisadas espacial e filogeneticamente. Resultados e discussão: Analisamos 613 amostras de soro durante 4 anos: 199 em 2006; 94 em 2007; 313 em 2008 e 10 em 2009. A positividade foi alta em 2006 e 2007, com 106 e 51 pacientes infectados, respectivamente. O principal sorotipo circulante durante as epidemias de 2006-2007 foi DENV-3 e poucos casos de DENV-2, o que pode ser a indicação de sua recente introdução no município. Nós também descrevemos a primeira epidemia de SLEV no Brasil em 2006. Dentre os pacientes com DENV em 2008, apenas sete estavam infectados com DENV-3 e 90 com DENV-2, sugerindo a reemergência do sorotipo. Nós Resumo xxiii detectamos a circulação de DENV-1 em dois pacientes em 2009 e em quatro pacientes em 2009. Aproximadamente 1200 mosquitos foram capturados entre Dezembro 2007 e Março de 2008. Capturamos 814 mosquitos Aedes aegypti, que foram divididos em 463 pools. Apenas 3,67% deles foram positivos para DENV-2 e DENV-3. Pools contendo apenas machos foram positivos para DENV, indicando a presença de transmissão transovariana. Nós obtivemos sequências de 82 pacientes dentre 174 amostras de sangue. Nós fomos capazes de geocodificar 46 sequências. O alinhamento gerou gerou nucleotídeos com 399 bp com 134 taxa. A análise filogenética indicou que todas as amostras foram de DENV-3 e estavam relacionadas às cepas circulantes na ilha da Martinica em 2000-2001. Sessenta pacientes com DENV- 3 de São José do Rio Preto formaram um grupo monofilético (linhagem 1), intimamente relacionado com os outros 22 isolados (linhagem 2). Nós assumimos que estas linhagens apareceram antes de 2006 em ocasiões diferentes. A possibilidade de inferir a dinâmica espaço-temporal através de dados genéticos é relativamente pouco explorada e pode esclarecer acirculação de DENV. O uso de dados filogenéticos estruturadosgeograficamente e temporalmente forneceu uma visão detalhada na dispersão de, pelo menos, duas cepas virais distintas numa área urbana.
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Denis, Jessica. „Discrimination sérologique de flavivirus, étude du domaine III de la protéine d’enveloppe du virus Zika comme cible d’anticorps spécifiques. High specificity and sensitivity of Zika EDIII-based ELISA diagnosis highlighted by a large human reference panel. Vector-Borne Transmission of the Zika Virus Asian Genotype in Europe“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS078.
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Le virus Zika fait partie du genre des Flavivirus comme le virus de la dengue. Ils sont transmis par les moustiques du genre Aedes. En 2015, une épidémie a causé plus de 700 000 infections, à l’origine de microcéphalies chez les fœtus et de syndromes de Guillain Barré. Pour la première fois, la transmission d’un arbovirus par voie sexuelle est mise en évidence. Les Flavivirus co-circulent dans de nombreux pays, parfois de façon concomitante. Leurs infections induisent des anticorps capables de reconnaitre différents Flavivirus. Cette réactivité croisée peut conduire, en fonction de leur concentration et de leur affinité à une séro-neutralisation virale croisée ou au contraire aggraver la pathologie liée à une seconde infection. Deux problématiques dues à cette réaction croisée apparaissent, (i) il est difficile de rendre un sérodiagnostic fiable et (ii) un vaccin pourrait induire, au contraire d’une protection, une aggravation des pathologies. Au cours de ces travaux, nous avons évalué la fiabilité de reconnaissance du domaine III de la protéine d’enveloppe du virus Zika par les anticorps qu’une infection virale induit chez l’homme. Ce domaine porte des épitopes reconnus spécifiquement par des IgG produits lors d’une infection par ce virus ce qui en fait un marqueur spécifique. L’ELISA mis au point a une sensibilité de 92% et une spécificité de 90%. Avec cet outil nous avons diagnostiqué un cas ancien présent dans une zone pré-épidémique ainsi qu’un cas autochtone dans le sud de la France en 2019. Le suivi de la cinétique d’apparition et de disparition des IgM et des IgG de patients pendant une année nous a permis d’estimer une fenêtre d’utilisation de notre diagnostic, tout en caractérisant les réponses immunitaires humorales liées à l’intensité des infections, la gravité de la pathologie ainsi que la présence d’une cicatrice sérologique. Enfin, l’étude d’anticorps induits par ce domaine complexé à une nanoparticule dans un modèle animal a montré un fort pouvoir adjuvant de ces nanoparticules ainsi qu’une reconnaissance spécifique du virus ZikaThe Zika virus, like the dengue virus, is a Flavivirus and both are transmitted by Aedes mosquitoes. In 2015, an epidemic caused more than 700,000 infections, leading to foetal microcephaly and Guillain Barré syndrome. In addition, sexual transmission of the Zika virus was demonstrated for the first time. Flaviviruses co-circulate in many countries, sometimes concomitantly. Infections with Flaviviruses induce cross-reacting antibodies, leading to cross-neutralization or, on the contrary, worsening of the disease following a second infection, depending on their concentration and affinity. Such cross-reaction leads to two principle problems: (i) it is difficult to make a reliable serodiagnosis and (ii) a vaccine may aggravate the disease instead of providing protection. Here, we evaluated the reliability of antibodies induced during human infections to recognise envelope protein domain III of the Zika virus. This domain carries epitopes recognized by the IgG produced during a Zika virus infection, making it a specific marker. An ELISA developed to detect this domain shows 92% sensitivity and 90% specificity. We used this tool to diagnose an old case from a pre-epidemic area as well as an indigenous case from the south of France in 2019. Monitoring the kinetics of the appearance and disappearance of IgM and IgG in the blood of patients for one year allowed us to estimate the window of use for our diagnostic tool, while characterizing the humoral immune responses linked to the epidemic and the severity of the disease, as well as the presence of a serological scar. Finally, the study of antibodies induced by this domain complexed to nanoparticles in an animal model showed such nanoparticles to be a strong adjuvant and the antibodies to specifically recognize the Zika virus
Bücher zum Thema "Flavivirus – Transmission"
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Nuttall, Patricia A. Tick-borne encephalitides. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0044.
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Tick-borne encephalitides are caused by three different viruses transmitted by ticks and belonging to the Flaviviridae virus family: tick-borne encephalitis virus (Far Eastern, Siberian, and European subtypes), louping ill virus, and Powassan virus (including deer tick virus). These viruses cause encephalitis affecting humans in Eurasia and North America. In nature, they are maintained in transmission cycles involving Ixodes tick species and small or medium-sized wild mammals. The tick-borne flavivirus group is one of the most intensely studied groups of tick-borne pathogens.
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Казачинская, Е. И. ВИРУС ДЕНГЕ. Академическое изд-во «Гео», 2021. http://dx.doi.org/10.21782/b978-5-6043022-6-2.
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The review is devoted to the analysis of literature data on the history research of dengue fever, the discovery of the etiological infectious agent of this disease-dengue virus and its serotypes. A taxonomic overview of the }lavivirus family, genome organization, structure and function of viral proteins, mosquito species-viral vectors and virus transmission cycles, theories of its origin are presented. As well as the evolution, characteristics and epidemiology of viral serotypes, cellular receptors for dengue virus penetration, pathogenicity for human and factors for the development of severe disease, induced immunity, applied methods and markers for diagnosis, principles of disease treatment and drug development (more information about monoclonal antibodies-potential therapeutic drugs), vaccine options and their effectiveness are considered. The book is intended for students, graduate students, employees of research institutions and universities, as well as doctors involved in the study of }laviviruses and the problem of differential diagnosis of flavivirus infections.
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Mesquita, Emersom C., und Fernando A. Bozza. Diagnosis and management of viral haemorrhagic fevers in the ICU. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0293.
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In a globalized scenario where widespread international travel allows viral agents to migrate from endemic to non-endemic areas, health care providers and critical care specialists must be able to readily recognize a suspected case of viral haemorrhagic fever (VHF). Early suspicion is pivotal for improving patient outcome and to ensure that appropriate biosafety measures be applied. VHFs are acute febrile illnesses marked by coagulation disorders and organ specific syndromes. VHFs represent a great medical challenge because diseases are associated with a high mortality rate and many VHFs have the potential for person-to-person transmission (Filoviruses, Arenavioruses, and Bunyaviroses). Dengue is the most frequent haemorrhagic viral disease and re-emergent infection in the world and, due to its public health relevance, severe dengue will receive special attention in this chapter. The diagnosis of VHFs is made by detecting specific antibodies, viral antigens (ELISA) and viral nucleic acid (RT-PCR) on blood samples. Supportive care is the cornerstone in the treatment of VHFs. Ribavirin should be started as soon as a case of VHF is suspected and discontinued if a diagnosis of Filovirus or Flavivirus infection is established. Adjunctive antimicrobial therapy is usually implemented to treat co-existing or secondary infections. Antimalarial treatment should also be initiated if a malaria test (thick blood films) is not quickly available and/or reliable and patients travel history is compatible. It is always recommended to apply appropriate biosafety measures and notify local infection control unit and state and national authorities.
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author, Olshaker Mark 1951, Hrsg. Deadliest enemy: Our war against killer germs. Little, Brown and Company, 2017.
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Osterholm, Michael T., und Mark Olshaker. Deadliest Enemy: Our War Against Killer Germs. Hodder & Stoughton, 2020.
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Osterholm, Michael T., und Mark Olshaker. Deadliest Enemy: Our War Against Killer Germs. Little Brown & Company, 2017.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "Flavivirus – Transmission"
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Schuch, Viviane, Felipe Martins, Felipe Ten Caten, Mariana Araujo-Pereira, Marielton Dos Passos Cunha, Nadia El Khawanky, Otavio Cabral-Marques und Helder I. Nakaya. „Systems immunology of flavivirus infection“. In Zika Virus Biology, Transmission, and Pathology, 221–34. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-820268-5.00020-1.
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Oxford, John, Paul Kellam und Leslie Collier. „Flaviviruses: yellow fever, dengue fever, and hepatitis C“. In Human Virology. Oxford University Press, 2016. http://dx.doi.org/10.1093/hesc/9780198714682.003.0012.
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This chapter focuses on flaviviruses and notes that there are at least 70 serotypes of flavivirus. The molecular clock analysis dates the sojourn of these viruses from 10 to 100,000 years. The prototype virus of this family causes yellow fever (YF), which is a classic disease of antiquity, and the application of the term white man’s grave to West Africa resulted from its impact on colonizers. The chapter refers to Carlos Finlay, who viewed the mosquito as the source and scourge of YF, but this was not proven until the volunteer experiments coordinated by Walter Reed in 1900. Other medically important flaviviruses are tick-borne encephalitis virus (TBE), dengue virus and West Nile virus, Japanese encephalitis, Murray Valley encephalitis virus, and Zika virus. The chapter highlights the hepatitis C virus, a well-researched member of the family that does not have the typical mosquito transmission of the other flaviviruses.
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Kumar, Swatantra, Rajni Nyodu, Vimal K. Maurya und Shailendra K. Saxena. „Pathogenesis and Host Immune Response during Japanese Encephalitis Virus Infection“. In Innate Immunity in Health and Disease. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98947.
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Japanese Encephalitis Virus (JEV) is a mosquito borne flavivirus infection. Transmission of JEV starts with the infected mosquito bite where human dermis layer act as the primary site of infection. Once JEV makes its entry into blood, it infects monocytes wherein the viral replication peaks up without any cell death and results in production of TNF-α. One of the most characteristics pathogenesis of JEV is the breaching of blood brain barrier (BBB). JEV propagation occurs in neurons that results in neuronal cell death as well as dissemination of virus into astrocytes and microglia leading to overexpression of proinflammatory cytokines. JEV infection results in host cells mediated secretion of various types of cytokines including type-1 IFN along with TNF-α and IFN-γ. Molecule like nitrous oxide (NO) exhibits antiviral activities against JEV infection and helps in inhibiting the viral replication by blocking protein synthesis and viral RNA and also in virus infected cells clearance. In addition, the antibody can also acts an opsonizing agent in order to facilitate the phagocytosis of viral particles, which is mediated by Fc or C3 receptor. This chapter focuses on the crucial mechanism of JEV induced pathogenesis including neuropathogenesis viral clearance mechanisms and immune escape strategies.
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Ooi, E. E., L. R. Petersen und D. J. Gubler. „Flaviviruses excluding dengue“. In Oxford Textbook of Medicine, 564–75. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.070514_update_001.
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Flaviviruses, family Flaviviridae, are enveloped viruses with a single-strand positive-sense RNA genome approximately 11 kb in length. They comprise 53 species (40 of which can cause human infection), divided into three major groups based on epidemiology and phylogenetics. They are maintained in nature in complex transmission cycles involving a variety of animals and hematophagous arthropods, which transmit infection to humans. IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) is widely used for diagnosis, with confirmation requiring a four-fold or greater rise in specific antibodies between acute and convalescent serum samples, virus isolation, detection of specific antigen by immunohistochemistry or of viral RNA by nucleic acid amplification from blood or other tissue sample....
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Frizon, Amanda Bartolomeu, Pedro Vieira Silva, Mariana Tonelli Ricci und Matheus Maia Henriques Malveira. „Dengue e outras Arboviroses“. In Doença do Pronto Atendimento. Editora Pascal LTDA, 2024. http://dx.doi.org/10.29327/5417839.1-2.
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As arboviroses são um grupo de doenças virais cuja transmissão ocorre, predominantemente, através de artrópodes, principalmente mosquitos e carrapatos. Entre essas doenças, destaca-se a dengue, causada pelos vírus pertencentes à família Flaviviridae, gênero Flavivirus. Os agentes etiológicos da dengue, denominados DENV, compreendem quatro sorotipos diversos, sendo eles: DENV-1, DENV-2, DENV-3 e DENV-4, caracterizados por variações genéticas em seus genótipos e linhagens. A transmissão do vírus da dengue ao ser humano ocorre, majoritariamente, por meio da picada de fêmeas infectadas do mosquito Aedes aegypti, que age como vetor principal. Outros modos de transmissão, como vertical (de mãe para filho durante a gestação) e por transfusão sanguínea, são considerados raros e infrequentes.
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Diaz, Adrián. „Flaviviruses and where the Zika virus fits in: An overview“. In Zika Virus Biology, Transmission, and Pathology, 3–18. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-820268-5.00001-8.
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Gritsun, T. S., und E. A. Gould. „Origin and Evolution of 3′Utr of Flaviviruses: Long Direct Repeats as A Basis for the Formation of Secondary Structures and Their Significance for Virus Transmission“. In Advances in Virus Research, 203–48. Elsevier, 2006. http://dx.doi.org/10.1016/s0065-3527(06)69005-2.
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„Virus isolations Mosquito collections obtained during most field trips to the north-west of Western Australia have been processed for virus isolation. Until 1985, virus isolation was undertaken by intracerebral inoculation of suckling mice, but this was then replaced by cell culture using C6/36 mosquito, PSEK, BHK and Vero cells. The use of cell culture has significantly reduced the overall virus isolation rate by largely excluding arboviruses, rhabdoviruses and most bunyaviruses, but is as effective as suckling mice for the isolation of flaviviruses and alphaviruses. MVE virus has been isolated every year that significant numbers of adult mosquitoes have been processed except 1983 (Broom et al. 1989; Broom et al. 1992; Mackenzie et al. 1994c). Isolations of MVE, Kunjin and other flaviviruses are shown in Table 8.2. There was a strong correlation between the number of virus isolates in any given year and the prevailing environmental conditions. Thus those years with a heavy, above average wet season rainfall and subsequent widespread flooding yielded large numbers of virus isolates (1981, 1991, 1993) compared with years with average or below average rainfall and with only localized flooding. Although most MVE virus isolates were obtained from Culex annulirostris mosquitoes, occasional isolates were also obtained from a variety of other species, including Culex quinquefasciatus, Culex palpalis, Aedes normanensis, Aedes pseudonormanensis, Aedes eidvoldensis, Aedes tremulus, Anopheles annulipes, Anopheles bancroftii, Anopheles amictus and Mansonia uniformis (cited in Mackenzie et al. 1994b; Mackenzie and Broom 1995), although the role of these species in natural transmission cycles has still to be determined. Virus carriage rates in Culex annulirostris mosquitoes are shown in Table 8.3 for the Ord River area (Kununurra–Wyndham) and Balgo and Billiluna in south-east Kimberley. Very high mosquito infection rates were observed in those years with above average rainfall. Virus spread and persistence Stanley (1979) suggested that viraemic waterbirds, which are often nomadic, may generate epidemic activity of MVE in south-east Australia and in the Pilbara region. In an attempt to understand the genesis of epidemic activity better, our laboratory initiated a long-term study in the arid south-east Kimberley area at Billiluna and Balgo, two Aboriginal communities on the northern edge of the Great Sandy Desert. Occasional cases of Australian encephalitis had occurred in both communities (1978, 1981). The studies have clearly shown that MVE virus activity only occurs following very heavy, widespread rainfall both locally and in the catchment area of the nearby watercourse, Sturt Creek, which results in extensive flooding across its floodplain (Broom et al. 1992). Localized flooding is insufficient to generate virus activity. Two possible explanations can be proposed to account for the reappearance of MVE virus activity when environmental conditions are suitable: either virus can be reintroduced into the area by viraemic waterbirds arriving from enzootic areas further north; or virus may“. In Water Resources, 133–35. CRC Press, 1998. http://dx.doi.org/10.4324/9780203027851-26.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Flavivirus – Transmission"
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Araújo, Simone Rodrigues da Silva, Ludmilla Pinto Guiotti Cintra Abreu, Ronaldo Gonçalves Abreu, Jardel Robert Henning Rodrigues de Magalhães, Maurício de Oliveira Chaves, Euzilene Felisberto Chaves, Maria Lúcia de Farias und Shairlon Luca dos Santos. „Yellow fever in Brazil: Reflections on vaccine safety and effectiveness“. In IV Seven International Congress of Health. Seven Congress, 2024. http://dx.doi.org/10.56238/homeivsevenhealth-004.
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Yellow fever is an arbovirus caused by a virus of the Flavivirus genus, endemic in tropical regions of Africa and South America. Transmission occurs mainly through the bite of infected mosquitoes, especially of the Haemagogus or Sabethes genera, which contract the virus from monkeys. There is also inter-human transmission via the Aedes aegypti mosquito. The disease is severe and hemorrhagic, with nonspecific initial symptoms, followed by periods of remission and toxemia, characterized by hemorrhagic manifestations and acute liver failure. Approximately 50% of cases are non-specific, 20% have few symptoms and 30% progress to fulminant forms, without specific treatment. Therefore, vaccination, early case detection, monitoring and life support are the main recommended strategies. Given the threat that yellow fever poses to public health in Brazil, a narrative review of the main articles on the safety and efficacy of the vaccine is justified.
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Rodrigues, Francisco, Andre Campino und Patricia Coelho. „Epidemiology of dengue in Portugal – a portrait“. In III SEVEN INTERNATIONAL MULTIDISCIPLINARY CONGRESS. Seven Congress, 2023. http://dx.doi.org/10.56238/seveniiimulti2023-226.
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Dengue is a systemic infectious disease of viral etiology transmitted through the bite of female hematophagous mosquitoes of the genus Aedes, with Aedes aegypti and Aedes albopictus being the most competent species for its transmission [1-4]. Dengue virus (VDEN) taxonomically belongs to the family Flaviviridae and the genus flavivirus [5-8]. To date, four antigenically differentiated serotypes - VDEN-1, VDEN-2, VDEN-3 and VDEN-4 - have been reported based on biological, immunological and molecular criteria [8,9]. Among all arboviruses, VDEN is by far the pathogen that most affects humans [10-13]. According to the World Health Organization (WHO) in the last 50 years the incidence of Dengue cases has increased by about 30 times, and it is estimated that there are currently between 50 and 100 million infections annually [10]. The disease is widespread in all tropical and subtropical regions of the planet, with a growing incidence in Asia, Africa, Latin America and the Pacific region [10,14]. It is estimated that approximately 2.5 billion people live at risk of contracting the disease in endemic countries [10,13]. Around 120 million people travel to affected areas each year, with travellers playing a key role in the geographical spread of the disease (the return of infected travellers from Dengue-endemic countries can establish autochthonous cycles of infection) [15,16, 17].
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Mj, Counotte, Maxwell L, Kim Cr, Broutet Njn und Low N. „O14.6 Sexual transmission of flaviviruses – a living systematic review“. In STI and HIV World Congress Abstracts, July 9–12 2017, Rio de Janeiro, Brazil. BMJ Publishing Group Ltd, 2017. http://dx.doi.org/10.1136/sextrans-2017-053264.83.
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Lins, Stephanie Ballatore Holland, Luane Tavares De Oliveira, Gabriela Lino Lopes, Maria Clara Costa Paulino, Diego De Lima Mamede und Danyelly Rodrigues Machado Azevedo. „COBERTURA VACINAL CONTRA FEBRE AMARELA NO ESTADO DE GOIÁS, 2009 A 2019“. In I Congresso Brasileiro de Doenças Infectocontagiosas On-line. Revista Multidisciplinar em Saúde, 2021. http://dx.doi.org/10.51161/rems/2244.
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Introdução: A febre amarela (FA) é uma doença infecciosa febril aguda provocada por um arbovírus do gênero Flavivirus, família Flaviviridae e transmitida por vetores artrópodes em dois ciclos de transmissão: silvestre e urbano. No ciclo urbano, o Aedes aegypti atua como vetor principal, enquanto no ciclo silvestre, mosquitos dos gêneros Haemagogus e Sabethes são responsáveis pela manutenção do vírus na natureza e sua transmissão entre primatas não humanos (PNH). Embora no Estado de Goiás não tenha sido registrado nenhum caso humano de FA desde 2017, seu ciclo silvestre não é passível de eliminação e, por ser uma zoonose, há necessidade contínua de vigilância e manutenção das ações de controle da doença, principalmente no que se refere à necessidade de ampliação da cobertura vacinal nesse Estado que é uma das áreas com recomendação da vacina (ACRV), conforme determinação do Ministério da Saúde (MS). Objetivo: Analisar a cobertura vacinal de febre amarela no Estado de Goiás, entre os anos de 2009 a 2019. Metodologia: Realizou-se uma análise da cobertura vacinal de FA datando de 2009 a 2019 com base nos registros do Programa Nacional de Imunização (PNI) através do site Mapa da Saúde, da Secretaria de Estado da Saúde de Goiás. O processamento e análise de dados foram realizados através do programa Microsoft Excel. Resultados: Dentro do período analisado de 2009 para 2019, a cobertura vacinal apresentou um decréscimo de 102,64% para 75,72%, respectivamente. No entanto, o maior percentual de vacinação contra FA foi em 2011, com 107,96% da população imunizada. Por recomendação da Organização Mundial de Saúde, a partir de abril de 2017 houve mudança do protocolo vacinal com indicação de dose única em todo o Brasil, o que poderia explicar a maior queda na cobertura vacinal no ano, com 76,05% de imunizados. Conclusão: Os resultados obtidos neste trabalho, indicam que a cobertura vacinal contra FA está abaixo do recomendado pelo MS, assim, conclui-se que as condições para disseminação da doença estão favoráveis, logo, são necessários esforços adicionais voltados às ações de vigilância, prevenção e controle da doença, principalmente no que tange o aumento da cobertura vacinal.