scholarly journals Flaviviruses – new human pathogens

2018 ◽  
Vol 72 ◽  
pp. 184-191
Author(s):  
Martyna Biała ◽  
Bartosz Jerczak ◽  
Małgorzata Inglot ◽  
Brygida Knysz
Keyword(s):  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Clinical Manifestations ◽  
Health Impact ◽  
Human Populations ◽  
Human Pathogens ◽  
Tick Borne Encephalitis ◽  
Animal Pathogens ◽  
The Family ◽  
Significant Public Health

The family Flaviviridae includes arthropod-borne viruses that are transmitted to vertebrates by infected mosquitoes and ticks. There are over a 100 species in this family, most of which are animal pathogens, although it cannot be excluded that some animal flaviviruses will also cause human disease. The family name is due to the discovery of the yellow fever virus and is derived from the Latin word flavus, meaning yellow. Several human-pathogenic flaviviruses have a significant public health impact in different parts of the world and the potential of emerging in previously non-endemic regions. The medically important flaviviruses include among others: dengue, Zika, yellow fever, tick‐borne encephalitis (TBE) and West Nile viruses. Diseases that are caused by these viruses include a spectrum of illnesses ranging from asymptomatic infections to severe and fatal disease. Although the characteristics of these viruses are well defined, they are still unpredictable with increases in disease severity, unusual clinical manifestations, unexpected methods of transmission, long-term persistence, and the discovery of new species. This review compares the epidemiological and clinical features of the medically important flaviviruses and considers the effect of human activity on their evolution and dispersal. Climate change, urbanization and increasing ease of travel have created opportunities for the vector to spread and expand into new human populations. The combination of these factors makes it possible for the family Flaviviridae to change and emerge quickly as a new, potential human pathogen.

scholarly journals Zika virus infection: a public health emergency!

2017 ◽  
Vol 3 (3) ◽  
pp. 68
Author(s):  
Muhammad Salman Haider Qureshi ◽  
Bakhtawar Wajeeha Qureshi ◽  
Ramsha Khan
Keyword(s):  
Public Health ◽  
West Nile Virus ◽  
Virus Infection ◽  
Dengue Virus ◽  
Yellow Fever ◽  
Zika Virus ◽  
Yellow Fever Virus ◽  
Public Health Emergency ◽  
Human Pathogens ◽  
The Family

<p class="abstract"><em>Zika virus</em> belongs to the family of Flaviviridae. The Flaviviridae family also includes other human pathogens like <em>West Nile virus</em> (WNV), <em>Yellow fever virus</em> (YFV), mosquito transmitted <em>Dengue virus</em> (DENV), <em>Tick borne encephalitic virus</em> (TBEV) and <em>Japanese encephalitis virus</em> (JEV). <em>Zika virus</em> is a mosquito-borne disease and is transmitted by <em>Aedes aegypti</em> mosquito<span lang="EN-IN">. </span></p>

scholarly journals Dengue and Zika virus 5’-UTRs harbor IRES functions

2019 ◽  
Author(s):  
Yutong Song ◽  
JoAnn Mugavero ◽  
Charles B. Stauft ◽  
Eckard Wimmer
Keyword(s):  
Yellow Fever ◽  
Zika Virus ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Human Populations ◽  
Human Pathogens ◽  
West Nile Fever ◽  
West Nile ◽  
Ribosomal Entry ◽  
Dependent Mechanism

AbstractMembers ofFlavivirus, a genus ofFlaviviridae, encompass numerous enveloped plus strand RNA viruses, of which globally dengue virus (DENV) is the leading cause of serious arthropod-borne disease. The genomes of DENV, just as those of yellow fever virus (YFV), West Nile fever virus (WNV), or Zika virus (ZIKV), control their translation by a 5’-terminal capping group. Three other genera of Flaviviridae are remarkable because their viruses use internal ribosomal entry sites (IRESs) to control translation and they are not arthropod transmitted. In 2006 E. Harris’ group published work suggesting that DENV RNA does not stringently need a cap for translation. They proposed that instead DENV translation is controlled by an interplay between 5’ and 3’ termini. Here we present evidence that the DENV or ZIKV 5’-untranslated regions (5’-UTRs) alone have IRES competence. This conclusion is based, first, on the observation that uncapped mono-cistronic mRNAs 5’ terminated with the DENV or ZIKV 5’-UTRs can efficiently direct translation of a reporter gene in BHK and C6/36 cells; second, that either 5’-UTR placed between two reporter genes can efficiently induce expression of the downstream gene in BHK but not in C6/36 cells. These experiments followed observations that uncapped DENV/ZIKV genomic transcripts, 5’ terminated with pppAN… or GpppAN…, can initiate infections of mammalian (BHK) or mosquito (C6/36) cells. IRES competence of the 5’-UTRs of DENV/ZIKV raises many open questions regarding the biology and control, as well as the evolution, of insect-borne flaviviruses.ImportanceMembers of the genusFlavivirusofFlaviviridaeare important human pathogens of great concern because they cause serious diseases, sometimes death, in human populations living in tropical, subtropical (dengue, DENV; Zika, ZIKV; yellow fever virus), or moderate climates (West Nile virus). Flaviviruses are known to control their translation by a cap-dependent mechanism. We have observed, however, that the uncapped genomes of DENV or ZIKV can initiate infection of mammalian and insect cells. We provide evidence that the short 5’ untranslated region (5’-UTR) of DENV or ZIKV genomes can fulfill the function of an internal ribosomal entry site (IRES). This strategy frees these organisms from the cap-dependent mechanism of gene expression at an as yet unknown stage of proliferation. The data raise new questions about the biology and evolution of flaviviruses, possibly leading to new controls of flavivirus disease.

Flaviviruses excluding dengue

2020 ◽  
pp. 830-845
Author(s):  
Shannan Lee Rossi ◽  
Nikos Vasilakis
Keyword(s):  
Japanese Encephalitis Virus ◽  
Host Range ◽  
Yellow Fever ◽  
Japanese Encephalitis ◽  
Human Infection ◽  
Virus Species ◽  
Human Pathogens ◽  
West Nile ◽  
The Family ◽  
Large Host

The family Flaviviridae currently consists of four recognized genera: Flavivirus, Pestivirus, Hepacivirus, and Pegivirus. Although members of the family have a large host range that includes both vertebrates and invertebrates, only members of the genus Flavivirus are known as arboviruses, vectored either by mosquitoes or ticks. The remaining genera in the family are exclusively found in mammals, and their diversity has greatly expanded with recent virus discoveries. The genus Flavivirus comprises 92 virus species, of which over 40 can cause human infection. Many of these include important human pathogens such as Zika, dengue, yellow fever, West Nile, and Japanese encephalitis virus.

scholarly journals Host-Specific NS5 Ubiquitination Determines Yellow Fever Virus Tropism

2019 ◽  
Vol 93 (14) ◽  
Author(s):  
Lisa Miorin ◽  
Maudry Laurent-Rolle ◽  
Giuseppe Pisanelli ◽  
Pierre Hendrick Co ◽  
Randy A. Albrecht ◽  
...  
Keyword(s):  
Animal Models ◽  
Mouse Model ◽  
Yellow Fever ◽  
Zika Virus ◽  
Yellow Fever Virus ◽  
Disease Model ◽  
Fever Virus ◽  
Type I ◽  
Human Pathogens ◽  
Immunocompetent Mouse

ABSTRACT The recent yellow fever virus (YFV) epidemic in Brazil in 2017 and Zika virus (ZIKV) epidemic in 2015 serve to remind us of the importance of flaviviruses as emerging human pathogens. With the current global flavivirus threat, there is an urgent need for antivirals and vaccines to curb the spread of these viruses. However, the lack of suitable animal models limits the research questions that can be answered. A common trait of all flaviviruses studied thus far is their ability to antagonize interferon (IFN) signaling so as to enhance viral replication and dissemination. Previously, we reported that YFV NS5 requires the presence of type I IFN (IFN-α/β) for its engagement with human signal transducer and activator of transcription 2 (hSTAT2). In this manuscript, we report that like the NS5 proteins of ZIKV and dengue virus (DENV), YFV NS5 protein is able to bind hSTAT2 but not murine STAT2 (mSTAT2). Contrary to what has been demonstrated with ZIKV NS5 and DENV NS5, replacing mSTAT2 with hSTAT2 cannot rescue the YFV NS5-STAT2 interaction, as YFV NS5 is also unable to interact with hSTAT2 in murine cells. We show that the IFN-α/β-dependent ubiquitination of YFV NS5 that is required for STAT2 binding in human cells is absent in murine cells. In addition, we demonstrate that mSTAT2 restricts YFV replication in vivo. These data serve as further impetus for the development of an immunocompetent mouse model that can serve as a disease model for multiple flaviviruses. IMPORTANCE Flaviviruses such as yellow fever virus (YFV), Zika virus (ZIKV), and dengue virus (DENV) are important human pathogens. A common flavivirus trait is the antagonism of interferon (IFN) signaling to enhance viral replication and spread. We report that like ZIKV NS5 and DENV NS5, YFV NS5 binds human STAT2 (hSTAT2) but not mouse STAT2 (mSTAT2), a type I IFN (IFN-α/β) pathway component. Additionally, we show that contrary to what has been demonstrated with ZIKV NS5 and DENV NS5, YFV NS5 is unable to interact with hSTAT2 in murine cells. We demonstrate that mSTAT2 restricts YFV replication in mice and that this correlates with a lack of IFN-α/β-induced YFV NS5 ubiquitination in murine cells. The lack of suitable animal models limits flavivirus pathogenesis, vaccine, and drug research. These data serve as further impetus for the development of an immunocompetent mouse model that can serve as a disease model for multiple flaviviruses.

scholarly journals Experience of application of IgY-technology for laboratory diagnostics of viral infections

2020 ◽  
Vol 65 (1) ◽  
pp. 21-26 ◽  
Author(s):  
A. P. Ivanov ◽  
T. D. Klebleeva ◽  
O. E. Ivanova
Keyword(s):  
Yellow Fever ◽  
Viral Infections ◽  
Yellow Fever Virus ◽  
Laboratory Diagnosis ◽  
Encephalitis Virus ◽  
Fever Virus ◽  
Laboratory Animals ◽  
Tick Borne Encephalitis ◽  
Tick Borne Encephalitis Virus

Introduction. The well-known advantages of class Y antibodies (IgY) from egg yolks of immunized hens in comparison with class G antibodies (IgG) of laboratory animals traditionally used in laboratory diagnosis of infectious diseases determine the stable interest of researchers in using IgY for these purposes (IgY technology) . Over the past 20 years, the obvious benefits of IgY technology have been demonstrated for a number of viral and bacterial infections. Goals and objectives. Construction of ELISA systems based on specific IgY for laboratory diagnosis of infections caused by tick-borne encephalitis virus, yellow fever virus, poliovirus.Material and methods. Obtaining yolk preparations of immunized chickens, obtaining highly purified IgY preparations (salting out, affinity chromatography), constructing ELISA systems for determining virus-specific antigens, testing the parameters of ELISA systems.Results and discussion. For the first time in laboratory practice, ELISA systems based on the use of specific polyclonal IgY were designed for laboratory diagnosis of topical human viral infections caused by flaviviruses and enteroviruses: determination of antigens of tick-borne encephalitis virus, yellow fever virus, 3 types of poliovirus. It was experimentally shown that these ELISA systems have high sensitivity and specificity, which allows them to be used for the semiquantitative and quantitative determination of antigens of these viruses in various materials (infected cell cultures, vaccines, etc.).Conclusion. The ELISA systems developed on the basis of specific IgY for determination of viral antigens can be effectively used for laboratory diagnosis of a number of viral infections, for the validation and control of vaccine preparations.

scholarly journals Salient Conclusive Remarks on Epidemiology and Clinical Manifestations of Pediatric COVID-19: Narrative Review

2020 ◽  
Vol 8 ◽  
Author(s):  
Abdelwahid Saeed Ali ◽  
Ahmed Mossa Al-Hakami ◽  
Ayed Abdullah Shati ◽  
Ali Alsuheel Asseri ◽  
Saleh Mohammed Al-Qahatani
Keyword(s):  
Clinical Manifestations ◽  
Primary Source ◽  
The Elderly ◽  
Narrative Review ◽  
Human Populations ◽  
Clinical Phenotypes ◽  
Virus Acquisition ◽  
Epidemiological Features ◽  
Significant Public Health ◽  
Novel Coronavirus

The ongoing pandemic of COVID-19, which is caused by the novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), constituted significant public health concerns and impacted the human populations with massive economic and social burdens worldwide. The disease is known to infect people of all ages, including children, adults, and the elderly. Although several reports about pediatric COVID-19 were seen in the literature, we believe that the epidemiology and pathology of the infection described in these reports are not conclusive. Therefore, in this scientific communication, a narrative review study was performed to shed some light on the characteristic epidemiological features and clinical phenotypes of pediatric COVID-19. In this report, we had compiled and presented the different epidemiological features of the disease related to the age of infection, virus acquisition, explanations of the low infectivity rates, and consequences of infections. The discriminatory clinical manifestations of the disease in children were also addressed and discussed in this review. The search included the data published from the date of the start of the pandemic in December 2019 up to October 2020. Our literature search revealed that children of all ages, including neonates, had been infected by the virus. Despite the fact that pediatric COVID-19 is less common to occur, as compared to the disease in adults, the infected children usually manifest the disease symptomatology in benign form. Asymptomatic and symptomatic adult patients are the primary source of the virus to the children. Intrauterine transmission of the virus and breastfeeding infections to the neonates were hypothesized in some studies but ruled out since they were not confirmed. Intensive review and discussion warranting the low infection rates and benign conditions of COVID-19 in children were also made in this study. As documented in many studies, the infectivity, morbidity, and mortality rates of the disease among the children populations are much lower than those in adults. They also seem to be lower than those observed during SARS-CoV and MERS-CoV epidemics. The described clinical phenotypes of COVID-19 in children do not differ much from those of adults, and complications of the disease seem to be associated with comorbidities.

scholarly journals Dengue 2 serotype and yellow fever coinfection

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Flávia Gehrke ◽  
Katharyna Cardoso Gois ◽  
Beatriz da Costa Alves Aguiar Reis ◽  
Gabriel Zorello Laporta ◽  
Fernando Luiz Affonso Fonseca
Keyword(s):  
Clinical Diagnosis ◽  
Yellow Fever ◽  
Laboratory Tests ◽  
Yellow Fever Virus ◽  
Genetic Material ◽  
High Sensitivity ◽  
Multiplex Assay ◽  
Case Presentation ◽  
Molecular Tests ◽  
The Family

Case Presentation. Arboviruses primarily consist of RNA, which favours greater genetic plasticity, with a higher frequency of mutations that allow the virus to adapt to different hosts. The initial symptomatology is nonspecific, in that the patient can present fever, myalgia, arthralgia, rash and headache. This makes a clinical diagnosis using laboratory tests difficult and time-consuming. In Brazil, the main arboviruses involved in epidemics belong to the family Flaviviridae. The patient in this case is from the municipality of São Bernardo do Campo, an area endemic for arboviruses. He presented symptoms of fever, myalgia and headache. Results. The multiplex assay for arboviruses detected genetic material from the dengue 2 and yellow fever viruses. Conclusion. This result confirms the importance of molecular tests showing high sensitivity and specificity that can assist clinical diagnosis, particularly in endemic areas during periods of outbreak for other arboviruses, like the epidemiological picture in Brazil in 2018, when significant co-circulation of dengue virus and yellow fever virus occurred. The presence of co-circulating arboviruses increases the chance of coinfection and demonstrates the importance of differential diagnosis.

scholarly journals Re-emergence of yellow fever in the neotropics — quo vadis?

2020 ◽  
Vol 4 (4) ◽  
pp. 411-422
Author(s):  
Livia Sacchetto ◽  
Betania P. Drumond ◽  
Barbara A. Han ◽  
Mauricio L. Nogueira ◽  
Nikos Vasilakis
Keyword(s):  
Yellow Fever ◽  
Amazon Basin ◽  
Yellow Fever Virus ◽  
Animal Health ◽  
Anthropogenic Factors ◽  
Human Populations ◽  
Sylvatic Cycle ◽  
Tropical Regions ◽  
Transmission Cycle ◽  
Quo Vadis

Yellow fever virus (YFV) is the etiological agent of yellow fever (YF), an acute hemorrhagic vector-borne disease with a significant impact on public health, is endemic across tropical regions in Africa and South America. The virus is maintained in two ecologically and evolutionary distinct transmission cycles: an enzootic, sylvatic cycle, where the virus circulates between arboreal Aedes species mosquitoes and non-human primates, and a human or urban cycle, between humans and anthropophilic Aedes aegypti mosquitoes. While the urban transmission cycle has been eradicated by a highly efficacious licensed vaccine, the enzootic transmission cycle is not amenable to control interventions, leading to recurrent epizootics and spillover outbreaks into human populations. The nature of YF transmission dynamics is multifactorial and encompasses a complex system of biotic, abiotic, and anthropogenic factors rendering predictions of emergence highly speculative. The recent outbreaks in Africa and Brazil clearly remind us of the significant impact YF emergence events pose on human and animal health. The magnitude of the Brazilian outbreak and spillover in densely populated areas outside the recommended vaccination coverage areas raised the specter of human — to — human transmission and re-establishment of enzootic cycles outside the Amazon basin. Herein, we review the factors that influence the re-emergence potential of YFV in the neotropics and offer insights for a constellation of coordinated approaches to better predict and control future YF emergence events.

Flaviviral RNAs: weapons and targets in the war between virus and host

2014 ◽  
Vol 462 (2) ◽  
pp. 215-230 ◽  
Author(s):  
Katell Bidet ◽  
Mariano A. Garcia-Blanco
Keyword(s):  
Rna Binding ◽  
Yellow Fever Virus ◽  
Rna Binding Proteins ◽  
Life Cycles ◽  
Human Pathogens ◽  
Cellular Functions ◽  
Tick Borne Encephalitis ◽  
Infected Cells ◽  
Non Coding Rnas

Flaviviruses are a genus of (+)ssRNA (positive ssRNA) enveloped viruses that replicate in the cytoplasm of cells of diverse species from arthropods to mammals. Many are important human pathogens such as DENV-1–4 (dengue virus types 1–4), WNV (West Nile virus), YFV (yellow fever virus), JEV (Japanese encephalitis virus) and TBEV (tick-borne encephalitis). Given their RNA genomes it is not surprising that flaviviral life cycles revolve around critical RNA transactions. It is these we highlight in the present article. First, we summarize the mechanisms governing flaviviral replication and the central role of conserved RNA elements and viral protein–RNA interactions in RNA synthesis, translation and packaging. Secondly, we focus on how host RNA-binding proteins both benefit and inhibit flaviviral replication at different stages of their life cycle in mammalian hosts. Thirdly, we cover recent studies on viral non-coding RNAs produced in flavivirus-infected cells and how these RNAs affect various aspects of cellular RNA metabolism. Together, the article puts into perspective the central role of flaviviral RNAs in modulating both viral and cellular functions.

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