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Mosquitoes collected in Finland were screened for flaviviral RNA leading to the discovery and isolation of a novel flavivirus designated Hanko virus (HANKV). Virus characterization, including phylogenetic analysis of the complete ...
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Mosquitoes collected in Finland were screened for flaviviral RNA leading to the discovery and isolation of a novel flavivirus designated Hanko virus (HANKV). Virus characterization, including phylogenetic analysis of the complete coding sequence, confirmed HANKV as a member of the "insect-specific" flavivirus (ISF) group. HANKV is the first member of this group isolated from northern Europe, and therefore the first northern European ISF for which the complete coding sequence has been determined. HANKV was not transcribed as DNA in mosquito cell culture, which appears atypical for an ISF. HANKV shared highest sequence homology with the partial NS5 sequence available for the recently discovered Spanish Ochlerotatus flavivirus (SOcFV). Retrospective analysis of mitochondrial sequences from the virus-positive mosquito pool suggested an Ochlerotatus mosquito species as the most likely host for HANKV. HANKV and SOcFV may therefore represent a novel group of Ochlerotatus-hosted insect-specific flaviviruses in Europe and further afield.
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We report the characterization of three novel flaviviruses isolated in Spain. Marisma Mosquito virus, a novel mosquito borne virus, was isolated from Ochlerotatus caspius mosquitoes; Spanish Ochlerotatus flavivirus and Spanish Cul...
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We report the characterization of three novel flaviviruses isolated in Spain. Marisma Mosquito virus, a novel mosquito borne virus, was isolated from Ochlerotatus caspius mosquitoes; Spanish Ochlerotatus flavivirus and Spanish Culex flavivirus, two novel insect flaviviruses, were isolated from Oc. caspius and Culex pipiens, respectively. During this investigation, we designed a sensitive RT-nested polymerase chain reaction method that amplifies a 1019bp fragment of the flavivirus NS5 gene and could be directly used in clinical or environmental samples for flavivirus characterization and surveillance. Analysis of the sequence generated from that amplicon contains enough phylogenetic information for proper taxonomic studies. Moreover, the use of this tool allowed the detection of additional flavivirus DNA forms in Culex, Culiseta, and Ochlerotatus mosquitoes.
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Previously, we reported a high prevalence of Culex flavivirus (CxFV) in Culex quinquefasciatus (Say) in the Yucatan Peninsula of Mexico. To determine whether other Culex spp. mosquitoes in this region are susceptible to natural Cx...
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Previously, we reported a high prevalence of Culex flavivirus (CxFV) in Culex quinquefasciatus (Say) in the Yucatan Peninsula of Mexico. To determine whether other Culex spp. mosquitoes in this region are susceptible to natural CxFV infection, Cx. bahamensis (Dyar and Knab), Cx. coronator (Dyar and Knab), Cx. interrogator (Dyar and Knab), Cx. nigripalpus (Theobald) and Cx. opisthopus (Komp) in the Yucatan Peninsula of Mexico were tested for CxFV. Two pools of Cx. interrogator were positive. The envelope protein genes of these isolates and 16 isolates from Cx. quinquefasciatus were sequenced and shown to have ≥99.2% nucleotide identity. These data suggest that there is limited genetic diversity among CxFV isolates in the Yucatan Peninsula of Mexico.
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Mutation of the West Nile virus-like particle (WN VLP) prM protein (T20D, K31A, K31V, or K31T) results in undetectable VLP secretion from transformed COS-1 cells. K31 mutants formed intracellular prM-E heterodimers; however these ...
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Mutation of the West Nile virus-like particle (WN VLP) prM protein (T20D, K31A, K31V, or K31T) results in undetectable VLP secretion from transformed COS-1 cells. K31 mutants formed intracellular prM-E heterodimers; however these proteins remained in the ER and ER-Golgi intermediary compartments of transfected cells. The T20D mutation affected glycosylation, heterodimer formation, and WN VLP secretion. When infectious viruses bearing the same mutations were used to infect COS-1 cells, K31 mutant viruses exhibited delayed growth and reduced infectivity compared to WT virus. Epitope maps of WN VLP and WNV prM were also different. These results suggest that while mutations in the prM protein can reduce or eliminate secretion of WN VLPs, they have less effect on virus. This difference may be due to the quantity of prM in WN VLPs compared to WNV or to differences in maturation, structure, and symmetry of these particles.
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Several flaviviruses are important pathogens for humans and animals (Dengue viruses, Japanese encephalitis virus, Yellow-fever virus, Tick-borne encephalitis virus, West Nile virus). In recent years, numerous novel and related fla...
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Several flaviviruses are important pathogens for humans and animals (Dengue viruses, Japanese encephalitis virus, Yellow-fever virus, Tick-borne encephalitis virus, West Nile virus). In recent years, numerous novel and related flaviviruses without known pathogenic capacity have been isolated worldwide in the natural mosquito population. However, phylogenetic studies have shown that genomic sequences of these viruses diverge from other flaviviruses. Moreover, these viruses seem to be exclusive of insects (they do not seem to grow on vertebrate cell lines), and were already defined as mosquito-only flaviviruses or insect-specific flaviviruses. At least eleven of these viruses were isolated worldwide, and sequences ascribable to other eleven putative viruses were detected in several mosquito species. A large part of the cycle of these viruses is not well known, and their persistence in the environment is poorly understood. These viruses are detected in a wide variety of distinct mosquito species and also in sandflies and chironomids worldwide; a single virus, or the genetic material ascribable to a virus, was detected in several mosquito species in different countries, often in different continents. Furthermore, some of these viruses are carried by invasive mosquitoes, and do not seem to have a depressive action on their fitness.
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Despite their worldwide occurrence, the distribution and role of insect-specific flaviviruses (ISFs) remain unclear. Methods: We evaluated the presence of ISFs in mosquitoes collected in S?o Paulo, Brazil, using reverse transcript...
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Despite their worldwide occurrence, the distribution and role of insect-specific flaviviruses (ISFs) remain unclear. Methods: We evaluated the presence of ISFs in mosquitoes collected in S?o Paulo, Brazil, using reverse transcription and semi-nested polymerase chain reaction (PCR). Some of the positive samples were subjected to nanopore sequencing. Results: Twelve mosquito pools (2.8%) tested positive for flavivirus infection. Nanopore sequencing was successfully performed on six samples. Phylogenetic analysis grouped these sequences into genotype 2 of Culex flavivirus (CxFV). Conclusions: The identification of CxFV genotype 2 at new locations in S?o Paulo highlights the importance of understanding the role of ISFs in mosquito vector competence.
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Mosquito-borne flaviviruses (MBFVs) are important cause of emerging and re-emerging human diseases nearly worldwide, transmitted by arthropod vectors (mostly aedes and culex mosquitoes), with particular reference to yellow fever v...
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Mosquito-borne flaviviruses (MBFVs) are important cause of emerging and re-emerging human diseases nearly worldwide, transmitted by arthropod vectors (mostly aedes and culex mosquitoes), with particular reference to yellow fever virus, Japanese encephalitis virus, dengue fever virus, St. Louis encephalitis virus, Murray Valley encephalitis virus, etc. In over 100 countries, more than 2.5 billion people are at risk of infection, and approximately 20 million infections are reported annually. Through the analysis of gene sequence data of these virus populations it is possible to infer phylogenetic relationships, which in turn can yield important epidemiological information, including their demographic history. Early attempts to define the evolutionary relationships and origins of viruses in the genus flavivirus are hampered by the lack of genetic information particularly amongst the MBFVs. In this study, complete genome, translated polyprotein, structural and non-structural proteins of MBFVs have been targeted and revealed an extensive series of clades defined by their epidemiology and disease associations. The branching patterns of at the deeper nodes of the resultant trees were different from those reported in the previous study. The significance of these observations is discussed.
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An estimated 3% of the world's population is chronically infected with hepatitis C virus (HCV). Although HCV was discovered more than 20 y ago, its origin remains obscure largely because no closely related animal virus homolog ...
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An estimated 3% of the world's population is chronically infected with hepatitis C virus (HCV). Although HCV was discovered more than 20 y ago, its origin remains obscure largely because no closely related animal virus homolog has been identified; furthermore, efforts to understand HCV pathogenesis have been hampered by the absence of animal models other than chimpanzees for human disease. Here we report the identification in domestic dogs of a nonprimate hepacivirus. Comparative phylogenetic analysis of the canine hepacivirus (CHV) confirmed it to be the most geneti cally similar animal virus homolog of HCV. Bayesian Markov chains Monte Carlo and associated time to most recent common ancestor analyses suggest a mean recent divergence time of CHV and HCV clades within the past 500-1,000 y, well after the domestication of canines. The discovery of CHV may provide new insights into the origin and evolution of HCV and a tractable model system with which to probe the pathogenesis, prevention, and treatment of diseases caused by hepacivirus infection.
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Koutango virus (KOUV), a close relative of West Nile virus, is highly neuroinvasive in animal models and has been associated with human disease. The complete genome of the KOUV prototype strain DakAnD5443 is reported here and may ...
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Koutango virus (KOUV), a close relative of West Nile virus, is highly neuroinvasive in animal models and has been associated with human disease. The complete genome of the KOUV prototype strain DakAnD5443 is reported here and may facilitate development of infectious clones for further characterization of this novel flavivirus.
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? 2022 Elsevier Inc.Septins are a family of GTP-binding proteins identified in insects and mammals. Septins are components of the cytoskeleton and participate in cytokinesis, chromosomal segregation, intracellular vesicular traffi...
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? 2022 Elsevier Inc.Septins are a family of GTP-binding proteins identified in insects and mammals. Septins are components of the cytoskeleton and participate in cytokinesis, chromosomal segregation, intracellular vesicular traffic, and response to pathogens. Human septin 6 was identified as necessary for hepatitis C virus replication. Information about host factors necessary for flavivirus replication in mosquitoes is scarce. Thus, the role of septins in the replicative cycle of dengue virus in Aedes spp. derived cells was investigated. Through bioinformatic analysis, sequences of septin-like proteins were identified. Infected mosquito cells showed increased expression of Sep2. Colocalization analysis, proximity ligation and immunoprecipitation assays indicated that Sep2 interacts with proteins E, NS3 and NS5, but not NS1. Immunoelectron microscopy evidenced the presence of AalSep2 in replicative complexes. Finally, silencing of Sep2 expression resulted in a significant decrease in virus progeny, indicating that Sep2 is a host factor participating in dengue virus replication in mosquito cells.
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