Search

Usutu virus (USUV; genus Flavivirus; family Flaviviridae) is a mosquito-borne, positive-sense RNA virus that is currently causing significant die-offs in numerous bird species throughout Europe and has caused infections in humans. Currently, there are no molecular clones for USUV, hence, hindering studies on the pathogenesis and transmission of USUV. Here, we demonstrate the development and characterization of infectious clones for two modern strains of USUV isolated from Europe and Africa. We show that the infectious clone-derived viruses replicated similarly to the parental strains in mammalian and insect cells. Additionally, we observed similar levels of replication and disease in two mouse models. These clones will aid the study of USUV infection, transmission, diagnostics, and vaccines.

Zika virus (ZIKV) is a mosquito-borne pathogen classified in the genus Flavivirus of the family Flaviviridae. Vertical transmission is considered to be the primary way to maintain some arboviruses ...

Zika virus (ZIKV) is an emerging mosquito-borne pathogen belonging to the genus Flavivirus of the family Flaviviridae. Aedes albopictus is widely distributed in China. However, little is known about the vector competence of Ae. albopictus in China. The present study presents the oral susceptibility and vector competence of Ae. albopictus Guangzhou strain to ZIKV. Additionally, vertical transmission of ZIKV is described. The results demonstrated the susceptibility of local Ae. albopictus mosquitoes to ZIKV with an extrinsic incubation period of 6 days. Disseminated infection was observed in Ae. albopictus starting on day 2 postinfection (PI). Starting on day 6 PI, the saliva of Ae. albopictus exhibited ZIKV infection, and the transmission rate was 36.4%. Vertical transmission was observed during the first gonotrophic cycle. The minimum infection rate was observed in third-to-fourth instar larvae.

The genus Flavivirus comprises numerous, small, single positive-stranded RNA viruses, many of which are important human pathogens. To store all the information required for their successful propagation, flaviviruses use discrete structural genomic RNA elements to code for functional information by the establishment of dynamic networks of long-range RNA–RNA interactions that promote specific folding. These structural elements behave as true cis-acting, non-coding RNAs (ncRNAs) and have essential regulatory roles in the viral cycle. These include the control of the formation of subgenomic RNAs, known as sfRNAs, via the prevention of the complete degradation of the RNA genome. These sfRNAs are important in ensuring viral fitness. This work summarizes our current knowledge of the functions performed by the genome conformations and the role of RNA–RNA interactions in these functions. It also reviews the role of RNA structure in the production of sfRNAs across the genus Flavivirus, and their existence in related viruses.

The mosquito-borne viruses belonging to the genus Flavivirus such as Dengue virus (DENV) and Zika virus (ZIKV) cause human infections ranging from mild flu-like symptoms to hemorrhagic fevers, hepatitis, and neuropathies. To date, there are vaccines only for few flaviviruses while no effective treatments are available. Pyridobenzothiazole (PBTZ) derivatives are a class of compounds endowed with a promising broad-spectrum anti-flavivirus activity and most of them have been reported as potent inhibitors of the flaviviral NS5 polymerase. However, synthesis of PBTZ analogues entails a high number of purification steps, the use of hazardous reagents and environmentally unsustainable generation of waste. Considering the promising antiviral activity of PBTZ analogues which require further exploration, in this work, we report the development of a new and sustainable three-component reaction (3CR) that can be combined with a basic hydrolysis in a one-pot procedure to obtain the PBTZ scaffold, thus reducing the number of synthetic steps, improving yields and saving time. 3CR was significantly explored in order to demonstrate its wide scope by using different starting materials. In addition, taking advantage of these procedures, we next designed and synthesized a new set of PBTZ analogues that were tested as anti-DENV-2 and anti-ZIKV agents. Compound 22 inhibited DENV-2 NS5 polymerase with an IC50 of 10.4 μM and represented the best anti-flavivirus compound of the new series by inhibiting DENV-2- and ZIKV-infected cells with EC50 values of 1.2 and 5.0 μM, respectively, that translates into attractive selectivity indexes (SI - 83 and 20, respectively). These results strongly reaffirm PBTZ derivatives as promising anti-flavivirus agents that now can be synthesized through a convenient and sustainable 3CR in order to obtain more potent compounds for further pre-clinical development studies.

Usutu virus (USUV; genus Flavivirus; family Flaviviridae) is a mosquito-borne, positive-sense RNA virus that is currently causing significant die-offs in numerous bird species throughout Europe and has caused infections in humans. Currently, there are no molecular clones for USUV, hence, hindering studies on the pathogenesis and transmission of USUV. In this report, we demonstrate the development and characterization of infectious clones for two modern strains of USUV isolated from Europe and Africa. We show that the infectious clone-derived viruses replicated similarly to the parental strains in both mammalian and insect cells. Additionally, we observed similar levels of replication and pathogenesis in two mouse models. This reverse genetics system will aid the scientific community in studying and developing USUV infection, transmission, diagnostics, and vaccines.

Japanese encephalitis is a mosquito-borne disease that occurs in Asia and is caused by Japanese encephalitis virus (JEV), a member of the genus Flavivirus. Although many flaviviruses can cause encephalitis, JEV causes particularly severe neurological manifestations. The virus causes loss of more disability-adjusted life years than any other arthropod-borne virus owing to the frequent neurological sequelae of the condition. Despite substantial advances in our understanding of Japanese encephalitis from in vitro studies and animal models, studies of pathogenesis and treatment in humans are lagging behind. Few mechanistic studies have been conducted in humans, and only four clinical trials of therapies for Japanese encephalitis have taken place in the past 10 years despite an estimated incidence of 69,000 cases per year. Previous trials for Japanese encephalitis might have been too small to detect important benefits of potential treatments. Many potential treatment targets exist for Japanese encephalitis, and pathogenesis and virological studies have uncovered mechanisms by which these drugs could work. In this Review, we summarize the epidemiology, clinical features, prevention and treatment of Japanese encephalitis and focus on potential new therapeutic strategies, based on repurposing existing compounds that are already suitable for human use and could be trialled without delay. We use our newly improved understanding of Japanese encephalitis pathogenesis to posit potential treatments and outline some of the many challenges that remain in tackling the disease in humans.

Background Zika virus is an emerging arbovirus of the family Flaviviridae and genus Flavivirus that until 2007 was restricted to a few cases of mild illness in Africa and Asia. Case presentation We report a case of atrial fibrillation disclosed during an acute Zika virus infection in a 49-year-old man. Different biological samples were analyzed for the molecular diagnosis of Zika by real-time PCR, however only the saliva specimen was positive. The patient’s wife tested positive in the serum sample, although she was an asymptomatic carrier. Moreover, a complete overview of patient’s biomarkers, including cytokines, chemokines, and growth-factors levels, was analyzed and compared to gender and age matching non-infected controls, as well as other Zika infected patients, considering the 95%CI of the mean values. Elevated levels of CXCL8, CCL11, CCL2, CXCL10, IL-1β, IL-6, TNF-α, IFN-γ, IL-17, IL-1Ra, IL-4, IL-9, FGF-basic, PDGF, G-CSF, and GM-CSF were observed in the Atrial fibrillation patient, in contrast to uninfected controls. Furthermore, increased levels of CCL5, IL-1β, TNF-α, IFN-γ, IL-9, G-CSF, and GM-CSF were observed only in the atrial fibrillation patient, when compared to other Zika patients. Conclusions To our knowledge, this is the first description of this type of cardiac disorder in Zika patients which may be considered another atypical manifestation during Zika virus infection.

To Fapespa, for granting a Master?s scholarship, to PNMG, for capture of the birds, to the Microbiology and Immunology Laboratory of the UFRA, for collection of the samples, and to the SAARB/IEC, for their support in the development of serological tests. Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Parque Natural?stico Mangal das Gar?as. Setor Veterin?rio. Bel?m, PA, Brasil. Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brasil. Universidade Federal Rural da Amaz?nia. Instituto da Sa?de e Produ??o Animal. Laborat?rio de Biologia Molecular. Bel?m, PA, Brasil. Universidade Federal Rural da Amaz?nia. Instituto da Sa?de e Produ??o Animal. Laborat?rio de Biologia Molecular. Bel?m, PA, Brasil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Bel?m, PA, Brasil. Universidade Federal Rural da Amaz?nia. Instituto da Sa?de e Produ??o Animal. Laborat?rio de Biologia Molecular. Bel?m, PA, Brasil. BACKGROUND: In this study, we evaluated the role of free-living domestic pigeons (Columba livia) as a reservoir of arboviruses in the city of Bel?m, state of Par?, Brazil. We investigated the presence of antibodies against the most prevalent arboviruses. OBJECTIVES: This study was aimed at evaluating some clinical and physical parameters of domestic pigeons, including the presence of antibodies to Amazon-endemic arboviruses. METHODS: Eighty-five healthy pigeons were captured in Mangal das Gar?as Park, in Bel?m, and were bled. Upon capture, the birds were subjected to a clinical examination in search of alterations that could indicate the presence of arboviruses. Blood samples were converted to serum and tested using the haemagglutination inhibition (HI) technique with a panel of 19 antigens of arboviruses circulating in the Amazon. The confirmation assay for the positive reactions to the viral species tested by HI was a neutralisation test in new-born Swiss albino mice (Mus musculus) [mouse neutralisation test (MNT)]. FINDINGS: A total of 10 (11.8%) serum samples tested positive for antiflavivirus antibodies by HI. All the samples positive for the HI test were subjected to MNT for detection of viruses and yielded negative results (logarithmic neutralisation index < 1.7). MAIN CONCLUSION: The results represent the first serological detection of antiarbovirus antibodies in domestic pigeons as potential hosts of arboviruses in Brazil. The detection of haemagglutination-inhibiting antibodies against genus Flavivirus indicated that there was recent contact between the analysed domestic pigeons and these arboviruses. Further studies are needed to evaluate the role of free-living pigeons in the maintenance cycle and spread of arboviruses in the Amazon.

Zika virus (ZIKV) is a mosquito-borne flavivirus. It was first isolated from Uganda in 1947 and has become an emergent event since 2007. However, because of the inconsistency of alignment methods, the evolution of ZIKV remains poorly understood. In this study, we first use the complete protein and an alignment-free method to build a phylogenetic tree of 87 Zika strains in which Asian, East African, and West African lineages are characterized. We also use the NS5 protein to construct the genetic relationship among 44 Zika strains. For the first time, these strains are divided into two clades: African 1 and African 2. This result suggests that ZIKV originates from Africa, then spread to Asia, Pacific islands, and throughout the Americas. We also perform the phylogeny analysis for 53 viruses in genus Flavivirus to which ZIKV belongs using complete proteins. Our conclusion is consistent with the classification by the hosts and transmission vectors.

West Nile virus (family Flaviviridae, genus Flavivirus) first caused human and veterinary disease, and was isolated from Culex pipiens pipiens L. and Aedes vexans (Meigen) (Diptera: Culicidae) in the United States in 1999. We report that a Connecticut strain of Ae. vexans was competent to transmit West Nile virus both horizontally to suckling mice and vertically to its progeny in the laboratory. Horizontal transmission was first observed on day 6 post-exposure (pe). Daily horizontal transmission rates generally increased with the day post-virus exposure with highest rates of 67–100% recorded on days 28–30 pe. One female vertically transmitted West Nile virus on day 21 pe, but only after it had taken its third bloodmeal. Horizontal and vertical transmission may contribute to West Nile virus infection rates in Ae. vexans in summer, and vertical transmission provides a means of survival of West Nile virus during winter.

Usutu virus (USUV) is an arbovirus within the genus flavivirus, which was first introduced to Southern Europe approximately twenty years ago causing epizootics among wild and captive birds. In Germany USUV was initially discovered in wild birds, mainly Common blackbirds (Turdus merula), in the Upper Rhine valley in southwest of the country in 2011 and has not spread much northwards since. Phylogenetic analyses revealed that the still ongoing USUV epidemic is caused by two different USUV strains, USUV-Germany belonging to the USUV Europe 3 lineage and USUV-Bonn belonging to the USUV Africa 3 lineage. The two strains were introduced independently. In August 2015 a new USUV strain, named USUV-Berlin, was isolated in Vero cells from two carcasses of juvenile Great grey owls (Strix nebulosa) kept in the Zoological Garden Berlin, which had suffered from a hyperacute fatal systemic infection. Both owls carried high USUV genome loads. Full-length USUV genomes sequences were determined and phylogenetic analysis demonstrated a close relationship with a Spanish mosquito-derived sequence from 2006. Immunohistochemical antigen detection in organ samples of the owls showed the typical USUV infection patterns. According to the phylogenetic analysis, USUV-Berlin belongs to the Africa 2 lineage, and can thus be distinguished from the other strains circulating in Germany. Repeated findings of different USUV strains suggest more frequent introductions into Central Europe and a higher mobility of this virus than assumed to date.

The last past two decades, there has been a tremendous expansion in the discovery and description of novel insect- specific viruses (ISVs). This has corresponded with progresses in metagenomic analyses for virus revealing and the increasing attention in insect microbiomes. Plentiful of the new ISVs seem to be members of the family Flaviviridae, genus Flavivirus, and are usual in insect populations in wildlife, with a global geographic circulation., En las últimas dos décadas, ha habido una gran expansión en el descubrimiento y la descripción de nuevos virus específicos de insectos (ISV). Esto se ha correspondido con los avances en los análisis metagenómicos para la revelación de virus y la creciente atención en microbiomas de insectos. Muchos de los nuevos ISV parecen ser miembros de la familia Flaviviridae, género Flavivirus, y son habituales en poblaciones de insectos en la vida silvestre, con una circulación geográfica global.

Japanese encephalitis (JE) is a serious arboviral disease caused by a virus of the genus Flavivirus. Japanese encephalitis is the most common vaccine-preventable virus causing encephalitis in Asia, affecting more than 50,000 persons and leading to 15,000 fatalities per year in endemic countries. For most travelers to Asia, the risk of Japanese encephalitis infection is extremely low and depends on destination, duration of travel, season, and activities. This article reviews travel-acquired Japanese encephalitis with a focus on epidemiology and prevention in the light of the newly available options for active immunization against Japanese encephalitis which have become available, and of the increasing popularity of travels to Japanese encephalitis endemic countries.

Objective Even during outbreaks, detection of Zika virus (ZIKV; genus Flavivirus, family Flaviviridae) in its mosquito vectors is surprisingly uncommon. Here we explore the reason for this apparent paradox and suggest strategies for improving the efficacy of ZIKV detection. Results There are several likely explanations for the rarity of ZIKV detection in field-collected mosquitoes during outbreaks, including the lag between the period when people are clinically ill and the initiation of entomological investigations, the prompt spraying of houses of identified cases, the difficulty of identifying some of the households of ZIKV infected cases, and the low efficiency of the sampling methods currently available. Thus, timely entomological investigation of suspected cases before the intervention of the vector control squad would enhance ZIKV detection from mosquitoes. For this to happen, administrative, financial and logistical issues must be solved before the beginning of outbreaks, and routine entomological surveillance must be conducted in foci of ZIKV amplification. Improving ZIKV detection during outbreaks is of paramount importance because identification of the mosquito species and population involved as vector in a given outbreak is a key element to a comprehensive and effective vector control strategy.

Zika virus (ZIKV; Genus Flavivirus, Family Flaviviridae) has recently emerged in Asia and the Americas to cause large outbreaks of human disease. The outbreak has been characterized by high attack rates, birth defects in infants and severe neurological complications in adults. ZIKV is transmitted to humans by Aedes mosquitoes, but recent evidence implicates sexual transmission as playing an important role as well. This review highlights the transmission of ZIKV in humans, with a focus on both mosquito and sexually-transmitted routes and their outcomes. We also discuss critical directions for future research.

Kyasanur forest disease virus (KFDV) belongs to the Flaviviridae family and genus Flavivirus that causes Kyasanur forest disease (KFD). It is a tick-borne viral infection which leads to either encephalitis or hemorrhage among infected individuals. The disease was first reported in 1957, from Shimoga district, state of Karnataka, with high mortality rate among nonhuman primates (NHPs) and human population living in the vicinity of Kyasanur forest, hence the name Kyasanur forest disease. In local language, KFD is known as “monkey fever” or “monkey disease” [1].

The genusFlavivirusincludes arthropod-borne viruses responsible for a large number of infections in humans and economically important animals. While RT-PCR protocols for specific detection of mostFlavivirusspecies are available, there has been also a demand for a broad-rangeFlavivirusassay covering all members of the genus. It is particularly challenging to balance specificity at genus level with equal sensitivity towards each target species. In the present study, a novel assay combining a SYBR Green-based RT-qPCR with a low-density DNA microarray has been developed. Validation experiments confirmed that the RT-qPCR exhibited roughly equal sensitivity of detection and quantification for all flaviviruses tested. These PCR products are subjected to hybridization on a microarray carrying 84 different oligonucleotide probes that represent all knownFlavivirusspecies. This assay has been used as a screening and confirmation tool forFlaviviruspresence in laboratory and field samples, and it performed successfully in international External Quality Assessment of NAT studies. Twenty-sixFlavivirusstrains were tested with the assay, showing equivalent or superior characteristics compared with the original or even with species-specific RT-PCRs. As an example, test results on West Nile virus detection in a panel of 340 mosquito pool samples from Greece are presented.

Dengue virus (DENV) is an arbovirus belonging to the genus Flavivirus , family Flaviviridae . In Brazil, the reemergence and spread of DENV type 4 (DENV-4) across the country were responsible for a significant outbreak in Guarujá, São Paulo, Brazil. Here, we report the first genomic sequences of DENV strains circulating in Guarujá during the 2013 outbreak.

Duck Tembusu virus (TMUV) is a newly emergent pathogen belonging to the Ntaya virus group in the genus Flavivirus. The clinical disease caused by TMUV infection has been recognized in ducks since 2010 and is characterized by severe egg drop and neurological manifestations. The infection is now endemic to Mainland China and affects domestic ducks, geese, and occasionally laying hens. A large amount of research has been directed toward this virus in recent years. In this chapter, we review the progress made in recent years in understanding the pathobiology of the virus, its diagnosis, and vaccine development.

West Nile virus, genus Flavivirus, is transmitted between birds and occasionally other animals by ornithophilic mosquitoes. This virus also infects humans causing asymptomatic infections in about 85% of cases and

Zika virus (ZIKV), belonging to the family Flaviviridae, genus Flavivirus, is an arthropod-borne virus that was first discovered from the Zika forest in Uganda in 1947. Recent outbreaks in South America have linked ZIKV to cases of microcephaly and Guillain-Barre syndrome in humans. With the increased interest in ZIKV, protocols must be established to facilitate proper research. Here we describe the laboratory techniques required to quantify, propagate, and store ZIVK. We also review the proper safety protocol for the handling of ZIKV, which is classified as a Biosafety Level 2 pathogen by the United States Centers for Disease Control and Prevention. © 2016 by John Wiley & Sons, Inc.

Zika virus belongs to the genus Flavivirus , and its spread remains an international public health emergency. In this report, we describe the obtainment and molecular characterization of a complete viral genome through the direct metagenomic analysis from saliva from an autochthonous transmission case in Mexico.

Zika virus (ZIKV), a mosquito-borne flavivirus, belongs to the Flaviviridae family, genus Flavivirus. ZIKV was initially isolated in 1947 from a sentinel monkey in the Zika forest, Uganda. Little clinical importance was attributed to ZIKV, once only few symptomatic cases were reported in some African and Southeast Asiatic countries. This situation changed in 2007, when a large outbreak was registered on the Yap Island, Micronesia, caused by the Asian ZIKV lineage. Between 2013 and 2014, ZIKV spread explosively and caused many outbreaks in different islands of the Southern Pacific Ocean and in 2015 autochthonous transmission was reported in Brazil. Currently, Brazil is the country with the highest number of ZIKV-positive cases in Latin America. Moreover, for the first time after the discovery of ZIKV, the Brazilian scientists are studying the possibility for the virus to cause severe congenital infection related to microcephaly and serious birth defects due to the time-spatial coincidence of the alarming increase of newborns with microcephaly and the Brazilian ZIKV epidemic. The present review summarizes recent information for ZIKV epidemiology, clinical picture, transmission, diagnosis and the consequences of this emerging virus in Brazil.

Dengue fever (DF) is an arboviral disease caused by a positive-sense RNA virus of the genus Flavivirus. The overall incidence of DF has increased exponentially worldwide over the last three decades. The atypical clinical manifestations of DF grouped under expanded dengue syndrome (EDS), have also been reported more frequently for the last decade. These unusual manifestations are usually associated with coinfections, comorbidities, or complications of prolonged shock. Intracranial hemorrhage (ICH) is one of the rare manifestations of the central nervous system involvement by dengue as a part of EDS. The pathogenesis and treatment of this manifestation also remain controversial. Therefore, we report a case of a previously healthy 65-year-old female who developed ICH as a part of EDS along with a brief review of literature.

Recent reports indicate that flaviviruses similar to the cell fusing agent virus (CFAV) naturally infect a wide variety of mosquito species. These newly recognized insect-specific viruses comprise a distinct CFAV complex within the genus Flavivirus. Here, we describe the isolation and characterization of nine strains of Culex flavivirus (Cx FV), a member of the CFAV complex, from mosquitoes collected in the United States (East Texas) and Trinidad. Phylogenetic analyses of the envelope protein gene sequences of these nine mosquito isolates with those of other CFAV complex flaviviruses in GenBank indicate that the U.S. isolates group with CxFV isolates from Asia (Japan and Indonesia), while the Trinidad isolates are more similar to CxFV isolates from Central America. A discussion follows on the possible biological significance of the CFAV complex flaviviruses.

Tembusu virus (TMUV) belongs to the genus Flavivirus that may cause severe egg drop in ducks. In order to evaluate the most efficient TMUV detection method, the performances of a conventional RT-PCR (C-RT-PCR), a semi-nested PCR (SN-RT-PCR), a reverse-transcriptase real-time quantitative PCR (Q-RT-PCR), and a reverse-transcription loop-mediated isothermal amplification (RT-LAMP) targeting the TMUV virus-specific NS5 gene were examined. In order to compare the sensitivity of these four techniques, two templates were used: (1) plasmid DNA that contained a partial region of the NS5 gene and (2) genomic RNA from TMUV-positive cell culture supernatants. The sensitivities using plasmid DNA detection by C-RT-PCR, SN-RT-PCR, Q-RT-PCR, and RT-LAMP were 2 × 10(4) copies/μL, 20 copies/μL, 2 copies/μL, and 20 copies/μL, respectively. The sensitivities using genomic RNA for the C-RT-PCR, SN-RT-PCR, Q-RT-PCR, and RT-LAMP were 100 pg/tube, 100, 10, and 100 fg/tube, respectively. All evaluated assays were specific for TMUV detection. The TMUV-specific RNA was detected in cloacal swabs from experimentally infected ducks using these four methods with different rates (52-92%), but not in the control (non-inoculated) samples. The sensitivities of RT-PCR, SN-RT-PCR, Q-RT-PCR, and RT-LAMP performed with cloacal swabs collected from suspected TMUV infected ducks within 2 weeks of severe egg-drop were 38/69 (55.1%), 52/69 (75.4%), 57/69 (82.6%), and 55/69 (79.7%), respectively. In conclusion, both RT-LAMP and Q-RT-PCR can provide a rapid diagnosis of TMUV infection, but RT-LAMP is more useful in TMUV field situations or poorly equipped laboratories.

Summary Recently, some cases of transfusion-transmitted infections of West Nile virus (WNV) have been reported. As a member of the genus flavivirus, WNV may cause a febrile illness with meningoenc

The past 30 years has seen a dramatic global increase in human disease caused by flaviviruses. There are approximately 60 members of the genus Flavivirus belonging to three epidemiologically distin...

TO THE EDITOR: West Nile virus (WNV) is a member of the genus Flavivirus within the Japanese encephalitis antigenic complex. The enzootic virus cycle involves transmission between avian hosts and ornithophilic mosquitoes, whereas humans and horses are considered dead-end hosts. Given the recent increase of WNV infection in humans and horses in Europe, concern has been raised regarding public and animal health.

The genus Flavivirus includes some of the most important human viral pathogens, and its members are found in all parts of the populated world. The temporal origin of diversification of the genus has long been debated due to the inherent problems with dating deep RNA virus evolution. A generally accepted hypothesis suggests that Flavivirus emerged within the last 10 000 years. However, it has been argued that the tick-borne Powassan flavivirus was introduced into North America some time between the opening and closing of the Beringian land bridge that connected Asia and North America 15 000–11 000 years ago, indicating an even older origin for Flavivirus. To determine the temporal origin of Flavivirus, we performed Bayesian relaxed molecular clock dating on a dataset with high coverage of the presently available Flavivirus diversity by combining tip date calibrations and internal node calibration, based on the Powassan virus and Beringian land bridge biogeographical event. Our analysis suggested that Flavivirus originated ~85 000 (64 000–110 000) or 120 000 (87 000–159 000) years ago, depending on the circumscription of the genus. This is significantly older than estimated previously. In light of our results, we propose that it is likely that modern humans came in contact with several members of the genus Flavivirus much earlier than suggested previously, and that it is possible that the spread of several flaviviruses coincided with, and was facilitated by, the migration and population expansion of modern humans out of Africa.

This study looked at the influence of interannual variations in temperature and precipitation on seasonal mosquito abundances, the prevalence of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in the northeastern United States, and the capacity for local mosquito communities to maintain and transmit WNV, defined as vector community competence. Vector and virus surveillance took place within Middlesex County in New Jersey over two transmission seasons (2010 and 2011). Drought conditions during the 2010 season were associated with significant increases in the number of blood-fed Culex spp. mosquitoes collected per week, and significant increases in vector community competence, or the ability of local vector communities to transmit WNV, when compared with the wetter and milder 2011 season. These increases were associated with significantly higher weekly WNV infection rates in Culex spp. (i.e., Culex pipiens L. and Culex restuans L.) during the 2010 drought season. On a larger scale, the positive influence of drought on the amplification of WNV was also confirmed at the state level where early seasonal (June-July) increases in temperature and decreases in precipitation were strongly correlated with increases in yearly WNV infection rates over a 9-yr period (2003-2011). These data suggest that there may be clear temperature and precipitation thresholds beyond which epidemic levels of WNV transmission occur.

Culex flavivirus (CxFV), a member of the genus flavivirus, is a novel insect-specific flaviviruses that can be divided into two subtypes, the cytopathic Asia/U.S. and the noncytopathic Africa/Caribbean/Latin American subtypes. The CxFV circulates in several Asian countries, and here we conducted the first study investigating CxFV in Taiwan. A total of 14,016 mosquitoes were collected between 2010 and 2012 and 3.4% (6/179) of the pools were CxFV-positive. The phylogenetic analyses indicate that the Taiwan isolates are closely related to the Africa/Caribbean/Latin American subtype, but form an independent cluster. In the cytology experiments, the CxFV Taiwan isolate infected only mosquito cells and caused cell-cell fusion that might be associated with a unique glycine residue at position 117 within the envelope protein, which is shared with the cytopathic effect-causing Asia/US subtype. This study marks the first time the Africa/Caribbean/Latin American subtype of CxFV has been identified in an Asian country and grouped into a novel cluster.

Virus-like particles (VLPs) are shell-like viruses that lack virus-specific genetic materials. Many viral-structured proteins can assemble into VLPs, which mimic the overall structure of virus particles and can elicit strong immune responses in a host. Dengue viruses (DENVs), from the genus Flavivirus, are transmitted to humans through the bites of an infected Aedes mosquito. DENVs cause several diseases that prevailed mainly in tropical and subtropical areas. However, effective treatment measures and preventive strategies for dengue diseases are still lacking. The present minireview summarized the assembly and maturation of DENVs, the strategies and effective factors for dengue VLP construction, and the application of DENV VLPs.

There has been an explosion in the discovery of ‘insect-specific’ flaviviruses and/or their related sequences in natural mosquito populations. Herein we review all ‘insect-specific’ flavivirus sequences currently available and conduct phylogenetic analyses of both the ‘insect-specific’ flaviviruses and available sequences of the entire genus Flavivirus. We show that there is no statistical support for virus–mosquito co-divergence, suggesting that the ‘insect-specific’ flaviviruses may have undergone multiple introductions with frequent host switching. We discuss potential implications for the evolution of vectoring within the family Flaviviridae. We also provide preliminary evidence for potential recombination events in the history of cell fusing agent virus. Finally, we consider priorities and guidelines for future research on ‘insect-specific’ flaviviruses, including the vast potential that exists for the study of biodiversity within a range of potential hosts and vectors, and its effect on the emergence and maintenance of the flaviviruses.

Dengue fever, dengue hemorrhagic fever and dengue shock syndrome are the prevalent mosquito borne viral infections worldwide. The dengue virus belongs to the genus flavivirus with conserved RNA domains peptidase_S7 and dexHc among its members. The secondary structures for RNA domains peptidase_S7 and DexHc are hence predicted and discussed with other known viral RNA structures to glean structural insights through comparison.

WEST Nile virus (wnv) is an arbovirus of the genus Flavivirus (family Flaviviridae), which is transmitted and amplified in enzootic cycles between avian hosts and many species of mosquito vectors ([Higgs and others 2004][1]). At least 59 mosquito species have been identified as vectors for wnv

To generate the most diverse phylogenetic dataset for the flaviviruses to date, we determined the genomic sequences and phylogenetic relationships of 14 flaviviruses, of which 10 are primarily associated with Culex spp. mosquitoes. We analyze these data, in conjunction with a comprehensive collection of flavivirus genomes, to characterize flavivirus evolutionary and biogeographic history in unprecedented detail and breadth. Based on the presumed introduction of yellow fever virus into the Americas via the transatlantic slave trade, we extrapolated a timescale for a relevant subset of flaviviruses whose evolutionary history, shows that different Culex-spp. associated flaviviruses have been introduced from the Old World to the New World on at least five separate occasions, with 2 different sets of factors likely to have contributed to the dispersal of the different viruses. We also discuss the significance of programmed ribosomal frameshifting in a central region of the polyprotein open reading frame in some mosquito-associated flaviviruses. ispartof: PLoS One vol:10 issue:2 ispartof: location:United States status: published

Rio Bravo virus (RBV) is a member of the family Flaviviridae , genus Flavivirus . It belongs to a group of viruses in the genus with no known vector. In this report, we analyze the complete genome of the prototype RBV, strain M64.

Novel flaviviruses that are genetically related to pathogenic mosquito-borne flaviviruses (MBFV) have been isolated from mosquitoes in various geographical locations, including Finland. We isolated and characterized another novel virus of this group from Finnish mosquitoes collected in 2007, designated as Ilomantsi virus (ILOV). Unlike the MBFV that infect both vertebrates and mosquitoes, the MBFV-related viruses appear to be specific to mosquitoes similar to the insect-specific flaviviruses (ISFs). In this overview of MBFV-related viruses we conclude that they differ from the ISFs genetically and antigenically. Phylogenetic analyses separated the MBFV-related viruses isolated in Africa, the Middle East and South America from those isolated in Europe and Asia. Serological cross-reactions of MBFV-related viruses with other flaviviruses and their potential for vector-borne transmission require further characterization. The divergent MBFV-related viruses are probably significantly under sampled to date and provide new information on the variety, properties and evolution of vector-borne flaviviruses., Highlights • Mosquito-borne flavivirus-related viruses were isolated from Finnish mosquitoes. • Isolates were reactive with flavivirus antibodies but appeared mosquito-specific. • Sequence analysis identified related viruses from different parts of the world. • These viruses represent unique properties among the mosquito-borne flavivirus group.

In Central Europe tick-borne encephalitis is one of the most frequent viral diseases of the central nervous system. There are geographic areas where these ticks occur in masses, and frequent visitors to such forests are most likely to be infected. The vector belongs to the genus Flavivirus of the Toga family.