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Antiviral Research Feb 2019The summer of 2018 in Germany was the second hottest and driest on record. These generally extremely favorable climatic conditions most likely triggered the further...
The summer of 2018 in Germany was the second hottest and driest on record. These generally extremely favorable climatic conditions most likely triggered the further expansion and the efficient propagation of the zoonotic arthropod-borne West Nile virus in many Southern/Southeastern and even Central European countries. WNV infections were detected for the first time in resident wild and aviary birds, such as common blackbirds, northern goshawks and great grey owls in Eastern and Southeastern Germany. The causative WNV strain belonged to the central European subclade II. Phylogeographic analysis indicated a single introduction event of WNV into Germany, most likely in 2016 from Czech Republic, and also a unique non-synonymous mutation in the NS3 gene. Extraordinary high temperatures in 2018 presumably led to decreased averaged extrinsic incubation period values for WNV in mosquitoes, leading to rapid virus amplification and greater transmission risk for vertebrates in Germany. Blood transfusion services and clinicians in Germany should be aware of these possible WNV infection risks in humans especially during late summer.
Topics: Animals; Bird Diseases; Birds; Culicidae; Germany; Seasons; Temperature; Weather; West Nile Fever; West Nile virus
PubMed: 30550796
DOI: 10.1016/j.antiviral.2018.12.005 -
Emerging Infectious Diseases Apr 2022West Nile virus (WNV) is an emergent arthropodborne virus that is transmitted from bird to bird by mosquitoes. Spillover events occur when infected mosquitoes bite...
West Nile virus (WNV) is an emergent arthropodborne virus that is transmitted from bird to bird by mosquitoes. Spillover events occur when infected mosquitoes bite mammals. We created a geopositioned database of WNV presence in Africa and considered reports of the virus in all animal components: reservoirs, vectors, and nonhuman dead-end hosts. We built various biogeographic models to determine which drivers explain the distribution of WNV throughout Africa. Wetlands of international importance for birds accounted for the detection of WNV in all animal components, whereas human-related drivers played a key role in the epizootic cases. We combined these models to obtain an integrative and large-scale perspective of the areas at risk for WNV spillover. Understanding which areas pose the highest risk would enable us to address the management of this spreading disease and to comprehend the translocation of WNV outside Africa through avian migration routes.
Topics: Africa; Animals; Culicidae; Mammals; Mosquito Vectors; West Nile Fever; West Nile virus
PubMed: 35318911
DOI: 10.3201/eid2804.211103 -
Brazilian Journal of Microbiology :... Mar 2021West Nile virus (WNV) is a mosquito-borne Flavivirus that can affect birds, horses, and humans, and is the only zoonotic Flavivirus that has been identified in six...
West Nile virus (WNV) is a mosquito-borne Flavivirus that can affect birds, horses, and humans, and is the only zoonotic Flavivirus that has been identified in six continents. In Brazil, until 2010, there was no evidence of WNV circulation. Recently, the virus was isolated from a horse with encephalitis, and the first human cases were registered in Brazil. Despite that, there is still no information on the enzootic cycle of this virus in birds or wildlife. This study aimed to investigate whether there is evidence of WNV circulation among wild birds from Southern Brazil. For this, we used free-living wild raptors (live-trapped or rescued) as potential sentinels to investigate the presence of WNV antibodies using ELISA and plaque reduction neutralization test (PRNT) assay. In addition, the presence of nucleic acids from Flavivirus family members was investigated. None of the birds sampled presented clinical findings compatible with WNV. Of the 200 serum samples from birds of prey belonging to 21 species, ten (5%) were positive for the presence of WNV antibodies on ELISA testing. The PRNT test did not confirm the ELISA results, but indicated that three birds had possibly been exposed to Saint Louis encephalitis virus (SLEV). All samples were negative for Flavivirus RNA. The results presented here evince the need for permanent surveillance for emerging flaviviruses in Brazil, as well as for a contingency policy in the case of human/animal outbreaks, particularly in high-risk areas.
Topics: Animals; Animals, Wild; Antibodies, Viral; Bird Diseases; Brazil; Flavivirus; Humans; Raptors; Seroepidemiologic Studies; West Nile Fever; West Nile virus
PubMed: 33108590
DOI: 10.1007/s42770-020-00393-z -
Viruses May 2023West Nile virus is a re-emerging arbovirus whose impact on public health is increasingly important as more and more epidemics and epizootics occur, particularly in...
West Nile virus is a re-emerging arbovirus whose impact on public health is increasingly important as more and more epidemics and epizootics occur, particularly in America and Europe, with evidence of active circulation in Africa. Because birds constitute the main reservoirs, migratory movements allow the diffusion of various lineages in the world. It is therefore crucial to properly control the dispersion of these lineages, especially because some have a greater health impact on public health than others. This work describes the development and validation of a novel whole-genome amplicon-based sequencing approach to West Nile virus. This study was carried out on different strains from lineage 1 and 2 from Senegal and Italy. The presented protocol/approach showed good coverage using samples derived from several vertebrate hosts and may be valuable for West Nile genomic surveillance.
Topics: Animals; Humans; West Nile virus; West Nile Fever; Europe; Italy; Senegal
PubMed: 37376561
DOI: 10.3390/v15061261 -
Viruses May 2023West Nile virus (WNV) neuroinvasive disease threatens the health and well-being of horses and humans worldwide. Disease in horses and humans is remarkably similar. The... (Review)
Review
West Nile virus (WNV) neuroinvasive disease threatens the health and well-being of horses and humans worldwide. Disease in horses and humans is remarkably similar. The occurrence of WNV disease in these mammalian hosts has geographic overlap with shared macroscale and microscale drivers of risk. Importantly, intrahost virus dynamics, the evolution of the antibody response, and clinicopathology are similar. The goal of this review is to provide a comparison of WNV infection in humans and horses and to identify similarities that can be exploited to enhance surveillance methods for the early detection of WNV neuroinvasive disease.
Topics: Humans; Horses; Animals; West Nile virus; West Nile Fever; Sentinel Surveillance; Mammals; Horse Diseases
PubMed: 37376530
DOI: 10.3390/v15061230 -
Virologica Sinica Feb 2021West Nile virus (WNV) is an important neurotropic flavivirus that is widely distributed globally. WNV strain XJ11129 was first isolated in Xinjiang, China, and its...
West Nile virus (WNV) is an important neurotropic flavivirus that is widely distributed globally. WNV strain XJ11129 was first isolated in Xinjiang, China, and its genetic and biological characteristics remain largely unknown. In this study, phylogenetic and sequence analyses revealed that XJ11129 belongs to lineage 1a and shares high genetic identity with the highly pathogenic strain NY99. Then, the full-length genomic cDNA of XJ11129 was amplified and assembled using a modified Gibson assembly (GA) method. The virus (named rXJ11129) was successfully rescued in days following this method. Compared with other wild-type WNV isolates, rXJ11129 exhibited virulence indistinguishable from that of the NY99 strain in vivo. In summary, the genomic and virulence phenotypes of rXJ11129 were characterized in vivo and in vitro, and these data will improve the understanding of the spread and pathogenesis of this reemerging virus.
Topics: China; Flavivirus; Humans; Phylogeny; West Nile Fever; West Nile virus
PubMed: 32632819
DOI: 10.1007/s12250-020-00246-x -
PLoS Pathogens Oct 2019It has been 20 years since West Nile virus first emerged in the Americas, and since then, little progress has been made to control outbreaks caused by this virus. After... (Review)
Review
It has been 20 years since West Nile virus first emerged in the Americas, and since then, little progress has been made to control outbreaks caused by this virus. After its first detection in New York in 1999, West Nile virus quickly spread across the continent, causing an epidemic of human disease and massive bird die-offs. Now the virus has become endemic to the United States, where an estimated 7 million human infections have occurred, making it the leading mosquito-borne virus infection and the most common cause of viral encephalitis in the country. To bring new attention to one of the most important mosquito-borne viruses in the Americas, we provide an interactive review using Nextstrain: a visualization tool for real-time tracking of pathogen evolution (nextstrain.org/WNV/NA). Nextstrain utilizes a growing database of more than 2,000 West Nile virus genomes and harnesses the power of phylogenetics for students, educators, public health workers, and researchers to visualize key aspects of virus spread and evolution. Using Nextstrain, we use virus genomics to investigate the emergence of West Nile virus in the U S, followed by its rapid spread, evolution in a new environment, establishment of endemic transmission, and subsequent international spread. For each figure, we include a link to Nextstrain to allow the readers to directly interact with and explore the underlying data in new ways. We also provide a brief online narrative that parallels this review to further explain the data and highlight key epidemiological and evolutionary features (nextstrain.org/narratives/twenty-years-of-WNV). Mirroring the dynamic nature of outbreaks, the Nextstrain links provided within this paper are constantly updated as new West Nile virus genomes are shared publicly, helping to stay current with the research. Overall, our review showcases how genomics can track West Nile virus spread and evolution, as well as potentially uncover novel targeted control measures to help alleviate its public health burden.
Topics: Computational Biology; Databases, Genetic; Disease Transmission, Infectious; Evolution, Molecular; Genome, Viral; Humans; United States; West Nile Fever; West Nile virus
PubMed: 31671157
DOI: 10.1371/journal.ppat.1008042 -
International Journal of Molecular... Nov 2020West Nile virus (WNV), like the dengue virus (DENV) and yellow fever virus (YFV), are major arboviruses belonging to the genus. WNV is emerging or endemic in many... (Review)
Review
West Nile virus (WNV), like the dengue virus (DENV) and yellow fever virus (YFV), are major arboviruses belonging to the genus. WNV is emerging or endemic in many countries around the world, affecting humans and other vertebrates. Since 1999, it has been considered to be a major public and veterinary health problem, causing diverse pathologies, ranging from a mild febrile state to severe neurological damage and death. WNV is transmitted in a bird-mosquito-bird cycle, and can occasionally infect humans and horses, both highly susceptible to the virus but considered dead-end hosts. Many studies have investigated the molecular determinants of WNV virulence, mainly with the ultimate objective of guiding vaccine development. Several vaccines are used in horses in different parts of the world, but there are no licensed WNV vaccines for humans, suggesting the need for greater understanding of the molecular determinants of virulence and antigenicity in different hosts. Owing to technical and economic considerations, WNV virulence factors have essentially been studied in rodent models, and the results cannot always be transported to mosquito vectors or to avian hosts. In this review, the known molecular determinants of WNV virulence, according to invertebrate (mosquitoes) or vertebrate hosts (mammalian and avian), are presented and discussed. This overview will highlight the differences and similarities found between WNV hosts and models, to provide a foundation for the prediction and anticipation of WNV re-emergence and its risk of global spread.
Topics: Animals; Culicidae; Disease Models, Animal; Disease Susceptibility; Host Specificity; Host-Pathogen Interactions; Humans; Invertebrates; Mosquito Vectors; Species Specificity; Vertebrates; Virulence; West Nile Fever; West Nile virus
PubMed: 33266206
DOI: 10.3390/ijms21239117 -
Viruses Sep 2019Although West Nile virus (WNV) has been a prominent mosquito-transmitted infection in North America for twenty years, no human vaccine has been licensed. With a... (Review)
Review
Although West Nile virus (WNV) has been a prominent mosquito-transmitted infection in North America for twenty years, no human vaccine has been licensed. With a cumulative number of 24,714 neurological disease cases and 2314 deaths in the U.S. since 1999, plus a large outbreak in Europe in 2018 involving over 2000 human cases in 15 countries, a vaccine is essential to prevent continued morbidity, mortality, and economic burden. Currently, four veterinary vaccines are licensed, and six vaccines have progressed into clinical trials in humans. All four veterinary vaccines require multiple primary doses and annual boosters, but for a human vaccine to be protective and cost effective in the most vulnerable older age population, it is ideal that the vaccine be strongly immunogenic with only a single dose and without subsequent annual boosters. Of six human vaccine candidates, the two live, attenuated vaccines were the only ones that elicited strong immunity after a single dose. As none of these candidates have yet progressed beyond phase II clinical trials, development of new candidate vaccines and improvement of vaccination strategies remains an important area of research.
Topics: Animals; Clinical Trials, Phase II as Topic; Drug Development; History, 21st Century; Humans; West Nile Fever; West Nile Virus Vaccines; West Nile virus
PubMed: 31491885
DOI: 10.3390/v11090823 -
Methods in Molecular Biology (Clifton,... 2023The plaque-forming assay is a gold standard technique to determine the concentration of infectious viral particles. In this assay, lytic viruses infect and lyse the...
The plaque-forming assay is a gold standard technique to determine the concentration of infectious viral particles. In this assay, lytic viruses infect and lyse the cells but are immobilized due to the presence of an agarose-containing overlay medium. The progeny viruses can only spread locally to and kill the adjacent cells and finally form a clear zone or plaque after staining the live cells. The number of plaques formed can be theoretically considered as the initial number of the infectious viral particles present in the sample and hence can be expressed as plaque-forming units (PFU) in a volume of the sample. Here, we provide a step-by-step method to carry out a plaque-forming assay to determine the titer of West Nile virus in a cell culture medium, which also can be adapted to other lytic viruses of eukaryotic cells.
Topics: West Nile virus; Viral Plaque Assay
PubMed: 36331760
DOI: 10.1007/978-1-0716-2760-0_2