RESUMO
Usutu virus (USUV) and West Nile virus (WNV) are two closely related emerging mosquito-borne flaviviruses. Their natural hosts are wild birds, but they can also cause severe neurological disorders in humans. Both viruses are efficiently suppressed by type I interferon (IFN), which interferes with viral replication, dissemination, pathogenesis and transmission. Here, we show that the replication of USUV and WNV are inhibited through a common set of IFN-induced genes (ISGs), with the notable exception of ISG20, which USUV is resistant to. Strikingly, USUV was the only virus among all the other tested mosquito-borne flaviviruses that demonstrated resistance to the 3'-5' exonuclease activity of ISG20. Our findings highlight that the intrinsic resistance of the USUV genome, irrespective of the presence of cellular or viral proteins or protective post-transcriptional modifications, relies on a unique sequence present in its 3' untranslated region. Importantly, this genomic region alone can confer ISG20 resistance to a susceptible flavivirus, without compromising its infectivity, suggesting that it could be acquired by other flaviviruses. This study provides new insights into the strategy employed by emerging flaviviruses to overcome host defense mechanisms.
Assuntos
Regiões 3' não Traduzidas , Flavivirus , Replicação Viral , Vírus do Nilo Ocidental , Regiões 3' não Traduzidas/genética , Flavivirus/genética , Flavivirus/fisiologia , Humanos , Animais , Replicação Viral/genética , Vírus do Nilo Ocidental/genética , Vírus do Nilo Ocidental/fisiologia , Infecções por Flavivirus/virologia , Exonucleases/metabolismo , Exonucleases/genética , Chlorocebus aethiops , Exorribonucleases/metabolismo , Exorribonucleases/genética , Células HEK293 , Células Vero , Linhagem Celular , Interferon Tipo I/metabolismo , Genoma ViralRESUMO
Insect-specific viruses (ISVs) include viruses that are restricted to the infection of mosquitoes and are spread mostly through transovarial transmission. Despite using a distinct mode of transmission, ISVs are often phylogenetically related to arthropod-borne viruses (arboviruses) that are responsible for human diseases and able to infect both mosquitoes and vertebrates. ISVs can also induce a phenomenon called "superinfection exclusion", whereby a primary ISV infection in an insect inhibits subsequent viral infections of the insect. This has sparked interest in the use of ISVs for the control of pathogenic arboviruses transmitted by mosquitoes. In particular, insect-specific flaviviruses (ISFs) have been shown to inhibit infection of vertebrate-infecting flaviviruses (VIFs) both in vitro and in vivo. This has shown potential as a new and ecologically friendly biological approach to the control of arboviral disease. For this intervention to have lasting impacts for biological control, it is imperative that ISFs are maintained in mosquito populations with high rates of vertical transmission. Therefore, these strategies will need to optimise vertical transmission of ISFs in order to establish persistently infected mosquito lines for sustainable arbovirus control. This review compares recent observations of vertical transmission of arboviral and insect-specific flaviviruses and potential determinants of transovarial transmission rates to understand how the vertical transmission of ISFs may be optimised for effective arboviral control.
Assuntos
Culicidae , Infecções por Flavivirus , Flavivirus , Transmissão Vertical de Doenças Infecciosas , Mosquitos Vetores , Vertebrados , Animais , Flavivirus/fisiologia , Flavivirus/genética , Flavivirus/classificação , Mosquitos Vetores/virologia , Culicidae/virologia , Infecções por Flavivirus/transmissão , Infecções por Flavivirus/virologia , Humanos , Vertebrados/virologia , Arbovírus/fisiologia , Arbovírus/classificaçãoRESUMO
The genus Flavivirus (Family: Flaviviridae) comprises arboviruses with the capacity to infect humans and animals. It also integrates insect-specific viruses. This study aimed to identify Flavivirus in mosquitoes captured in 17 municipalities in Yucatan State, Mexico. The mosquitoes were caught in households from November 2021 to May 2022. A total of 4,321 adult mosquitoes from five species were caught. The most abundant were Culex quinquefasciatus (n = 3,563) and Aedes aegypti (n = 734). For molecular investigations, 600 female mosquitoes were split into groups of 10, mostly for species and site location. Reverse transcriptase polymerase chain reaction (RT-PCR) amplified a region of the NS5 gene to find the Flavivirus ribonucleic acids (RNA). A total of 24 pools that were positive for Flavivirus were detected in Ae. aegypti specimens and subsequently subjected to sequencing using the Sanger method. A total of 12 sequences matched the established quality criteria and were subsequently employed for sequence homology analysis. We found that one sequence corresponded to the Zika virus (ZIKV), and 11 sequences had sequence similarity with Phlebotomus-associated flavivirus (PAFV), an insect-specific virus (ISF). In conclusion, we found ZIKV in the Merida municipality, Yucatan State, which suggests that the virus is silently circulating. Phlebotomus-associated flavivirus is distributed in five municipalities in Yucatan State, Mexico. Future studies could focus on isolating this virus and studying its biological role within Ae. aegypti.
Assuntos
Culicidae , Flavivirus , Mosquitos Vetores , Animais , México , Flavivirus/genética , Flavivirus/isolamento & purificação , Flavivirus/classificação , Mosquitos Vetores/virologia , Feminino , Culicidae/virologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , RNA Viral/genética , RNA Viral/análise , Culex/virologiaRESUMO
MicroRNAs (miRNAs) are molecules that influence messenger RNA (mRNA) expression levels by binding to the 3' untranslated region (3' UTR) of target genes. Host miRNAs can influence flavivirus replication, either by inducing changes in the host transcriptome or by directly binding to viral genomes. The 3' UTR of the flavivirus genome is a conserved region crucial for viral replication. Cells might exploit this well-preserved region by generating miRNAs that interact with it, ultimately impacting viral replication. Despite significant efforts to identify miRNAs capable of arresting viral replication, the potential of all these miRNAs to interact with the flavivirus 3' UTR is still poorly characterised. In this context, bioinformatic tools have been proposed as a fundamental part of accelerating the discovery of interactions between miRNAs and the 3' UTR of viral genomes. In this study, we performed a computational analysis to reveal potential miRNAs from human and mosquito species that bind to the 3' UTR of flaviviruses. In humans, miR-6842 and miR-661 were found, while in mosquitoes, miR-9-C, miR-2945-5p, miR-11924, miR-282-5p, and miR-79 were identified. These findings open new avenues for studying these miRNAs as antivirals against flavivirus infections.
Assuntos
Regiões 3' não Traduzidas , Biologia Computacional , Flavivirus , Genoma Viral , MicroRNAs , MicroRNAs/genética , MicroRNAs/metabolismo , Regiões 3' não Traduzidas/genética , Flavivirus/genética , Humanos , Animais , Biologia Computacional/métodos , Replicação Viral/genética , Antivirais/farmacologia , Infecções por Flavivirus/virologia , Infecções por Flavivirus/genética , Culicidae/virologia , Culicidae/genéticaRESUMO
Bagaza virus (BAGV) is a mosquito-borne flavivirus of the family Flaviviridae, genus Orthoflavivirus, Ntaya serocomplex. Like other viruses of the Ntaya and Japanese encephalitis serocomplexes, it is maintained in nature in transmission cycles involving viremic wild bird reservoirs and Culex spp. mosquitoes. The susceptibility of red-legged partridge, ring-necked pheasant, Himalayan monal and common wood pigeon is well known. Determining whether other species are susceptible to BAGV infection is fundamental to understanding the dynamics of disease transmission and maintenance. In September 2023, seven Eurasian magpies were found dead in a rural area in the Mértola district (southern Portugal) where a BAGV-positive cachectic red-legged partridge had been found two weeks earlier. BAGV had also been detected in several red-legged partridges in the same area in September 2021. Three of the magpies were tested for Bagaza virus, Usutu virus, West Nile virus, Avian influenza virus and Avian paramyxovirus serotype 1, and were positive for BAGV only. Sequencing data confirmed the specificity of the molecular detection. Our results indicate that BAGV is circulating in southern Portugal and confirm that Eurasian magpie is potential susceptible to BAGV infection. The inclusion of the abundant Eurasian magpie in the list of BAGV hosts raises awareness of the potential role of this species as as an amplifying host.
Assuntos
Flavivirus , Animais , Portugal , Flavivirus/genética , Flavivirus/isolamento & purificação , Filogenia , Doenças das Aves/virologia , Doenças das Aves/epidemiologia , Infecções por Flavivirus/virologia , Infecções por Flavivirus/veterinária , Infecções por Flavivirus/transmissão , Infecções por Flavivirus/epidemiologiaRESUMO
Tick-borne encephalitis virus (TBEV) is a neurotropic member of the genus Orthoflavivirus (former Flavivirus) and is of significant health concern in Europe and Asia. TBEV pathogenesis may occur directly via virus-induced damage to neurons or through immunopathology due to excessive inflammation. While primary cells isolated from the host can be used to study the immune response to TBEV, it is still unclear how well these reflect the immune response elicited in vivo. Here, we compared the transcriptional response to TBEV and the less pathogenic tick-borne flavivirus, Langat virus (LGTV), in primary monocultures of neurons, astrocytes and microglia in vitro, with the transcriptional response in vivo captured by single-nuclei RNA sequencing (snRNA-seq) of a whole mouse cortex. We detected similar transcriptional changes induced by both LGTV and TBEV infection in vitro, with the lower response to LGTV likely resulting from slower viral kinetics. Gene set enrichment analysis showed a stronger transcriptional response in vivo than in vitro for astrocytes and microglia, with a limited overlap mainly dominated by interferon signaling. Together, this adds to our understanding of neurotropic flavivirus pathogenesis and the strengths and limitations of available model systems.
Assuntos
Astrócitos , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Microglia , Neurônios , Animais , Astrócitos/virologia , Microglia/virologia , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Vírus da Encefalite Transmitidos por Carrapatos/patogenicidade , Camundongos , Neurônios/virologia , Encefalite Transmitida por Carrapatos/virologia , Infecções por Flavivirus/virologia , Infecções por Flavivirus/imunologia , Células Cultivadas , Flavivirus/fisiologia , Flavivirus/genética , Camundongos Endogâmicos C57BL , Transcrição GênicaRESUMO
BACKGROUND: Mosquito host feeding patterns are an important factor of the species-specific vector capacity determining pathogen transmission routes. Culex pipiens s.s./Cx. torrentium are competent vectors of several arboviruses, such as West Nile virus and Usutu virus. However, studies on host feeding patterns rarely differentiate the morphologically indistinguishable females. METHODS: We analyzed the host feeding attraction of Cx. pipiens and Cx. torrentium in host-choice studies for bird, mouse, and a human lure. In addition, we summarized published and unpublished data on host feeding patterns of field-collected specimens from Germany, Iran, and Moldova from 2012 to 2022, genetically identified as Cx. pipiens biotype pipiens, Cx. pipiens biotype molestus, Cx. pipiens hybrid biotype pipiens × molestus, and Cx. torrentium, and finally put the data in context with similar data found in a systematic literature search. RESULTS: In the host-choice experiments, we did not find a significant attraction to bird, mouse, and human lure for Cx. pipiens pipiens and Cx. torrentium. Hosts of 992 field-collected specimens were identified for Germany, Iran, and Moldova, with the majority determined as Cx. pipiens pipiens, increasing the data available from studies known from the literature by two-thirds. All four Culex pipiens s.s./Cx. torrentium taxa had fed with significant proportions on birds, humans, and nonhuman mammals. Merged with the data from the literature from 23 different studies showing a high prevalence of blood meals from birds, more than 50% of the blood meals of Cx. pipiens s.s. were identified as birds, while up to 39% were human and nonhuman mammalian hosts. Culex torrentium fed half on birds and half on mammals. However, there were considerable geographical differences in the host feeding patterns. CONCLUSIONS: In the light of these results, the clear characterization of the Cx. pipiens s.s./Cx. torrentium taxa as ornithophilic/-phagic or mammalophilic/-phagic needs to be reconsidered. Given their broad host ranges, all four Culex taxa could potentially serve as enzootic and bridge vectors.
Assuntos
Aves , Culex , Comportamento Alimentar , Mosquitos Vetores , Animais , Culex/fisiologia , Culex/virologia , Culex/classificação , Camundongos , Humanos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Mosquitos Vetores/classificação , Feminino , Alemanha , Irã (Geográfico) , Especificidade de Hospedeiro , Vírus do Nilo Ocidental/fisiologia , Vírus do Nilo Ocidental/genética , Flavivirus/genética , Flavivirus/fisiologia , Flavivirus/isolamento & purificação , Especificidade da EspécieRESUMO
One third of all emerging infectious diseases are vector-borne, with no licensed antiviral therapies available against any vector-borne viruses. Zika virus and Usutu virus are two emerging flaviviruses transmitted primarily by mosquitoes. These viruses modulate different host pathways, including the PI3K/AKT/mTOR pathway. Here, we report the effect on ZIKV and USUV replication of two AKT inhibitors, Miransertib (ARQ-092, allosteric inhibitor) and Capivasertib (AZD5363, competitive inhibitor) in different mammalian and mosquito cell lines. Miransertib showed a stronger inhibitory effect against ZIKV and USUV than Capivasertib in mammalian cells, while Capivasertib showed a stronger effect in mosquito cells. These findings indicate that AKT plays a conserved role in flavivirus infection, in both the vertebrate host and invertebrate vector. Nevertheless, the specific function of AKT may vary depending on the host species. These findings indicate that AKT may be playing a conserved role in flavivirus infection in both, the vertebrate host and the invertebrate vector. However, the specific function of AKT may vary depending on the host species. A better understanding of virus-host interactions is therefore required to develop new treatments to prevent human disease and new approaches to control transmission by insect vectors.
Assuntos
Infecções por Flavivirus , Flavivirus , Proteínas Proto-Oncogênicas c-akt , Replicação Viral , Zika virus , Animais , Flavivirus/fisiologia , Flavivirus/efeitos dos fármacos , Flavivirus/genética , Humanos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Linhagem Celular , Zika virus/fisiologia , Zika virus/efeitos dos fármacos , Infecções por Flavivirus/virologia , Infecções por Flavivirus/transmissão , Vertebrados/virologia , Antivirais/farmacologia , Mosquitos Vetores/virologia , Chlorocebus aethiops , Culicidae/virologia , Interações Hospedeiro-PatógenoRESUMO
The family Cimicidae comprises ectoparasites feeding exclusively on the blood of endothermic animals. Cimicid swallow bugs specifically target swallow birds (Hirundinidae) and their nestlings in infested nests. Bugs of the genus Oeciacus are commonly found in mud nests of swallows and martins, while they rarely visit the homes of humans. Although-unlike other cimicid species-the house martin bug Oeciacus hirundinis has never been reported as a vector of zoonotic pathogens, its possible role in arbovirus circulation in continental Europe is unclear. Samples of O. hirundinis were therefore collected from abandoned house martin (Delichon urbicum) nests in southern Moravia (Czech Republic) during the 2021/2022 winter season and checked for alpha-, flavi- and bunyaviruses by RT-PCR. Of a total of 96 pools consisting of three adult bugs each, one pool tested positive for Usutu virus (USUV)-RNA. Phylogenetic analysis showed that the virus strain was closely related to Italian and some Central European strains and corresponded to USUV lineage 5. The detection of USUV in O. hirundinis during wintertime in the absence of swallows raises the question for a possible role of this avian ectoparasite in virus overwintering in Europe.
Assuntos
Cimicidae , Flavivirus , Filogenia , Estações do Ano , Animais , Cimicidae/virologia , Flavivirus/isolamento & purificação , Flavivirus/genética , Flavivirus/classificação , República Tcheca , RNA Viral/genética , Doenças das Aves/parasitologia , Doenças das Aves/virologiaRESUMO
Usutu virus (USUV) is an emerging flavivirus that can infect birds and mammals. In humans, in severe cases, it may cause neuroinvasive disease. The innate immune system, and in particular the interferon response, functions as the important first line of defense against invading pathogens such as USUV. Many, if not all, viruses have developed mechanisms to suppress and/or evade the interferon response in order to facilitate their replication. The ability of USUV to antagonize the interferon response has so far remained largely unexplored. Using dual-luciferase reporter assays we observed that multiple of the USUV nonstructural (NS) proteins were involved in suppressing IFN-ß production and signaling. In particular NS4A was very effective at suppressing IFN-ß production. We found that NS4A interacted with the mitochondrial antiviral signaling protein (MAVS) and thereby blocked its interaction with melanoma differentiation-associated protein 5 (MDA5), resulting in reduced IFN-ß production. The TM1 domain of NS4A was found to be essential for binding to MAVS. By screening a panel of flavivirus NS4A proteins we found that the interaction of NS4A with MAVS is conserved among flaviviruses. The increased understanding of the role of NS4A in flavivirus immune evasion could aid the development of vaccines and therapeutic strategies.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Flavivirus , Helicase IFIH1 Induzida por Interferon , Interferon beta , Transdução de Sinais , Proteínas não Estruturais Virais , Proteínas não Estruturais Virais/metabolismo , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/imunologia , Humanos , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Flavivirus/imunologia , Flavivirus/genética , Flavivirus/fisiologia , Interferon beta/genética , Interferon beta/imunologia , Interferon beta/metabolismo , Helicase IFIH1 Induzida por Interferon/genética , Helicase IFIH1 Induzida por Interferon/metabolismo , Helicase IFIH1 Induzida por Interferon/imunologia , Células HEK293 , Evasão da Resposta Imune , Infecções por Flavivirus/imunologia , Infecções por Flavivirus/virologia , Interações Hospedeiro-Patógeno/imunologia , Ligação Proteica , Imunidade Inata , AnimaisRESUMO
Usutu virus (USUV) is a mosquito-borne flavivirus originating from Africa, that belongs to the Japanese encephalitis virus (JEV) complex. In nature, USUV involves Culex spp. mosquitoes acting as vectors and birds as amplifying hosts. The virus has recently spread in Europe and is considered an emerging human pathogen. This is the first research study performed in Greece revealing the presence and circulation of USUV in Culex spp. mosquito populations. Out of the 1,500 mosquito pools tested with real-time RT-PCR, four (Roesch et al., 2019) were positive for USUV. All four pools were collected from the region of Central Macedonia, Northern Greece.
Assuntos
Culex , Flavivirus , Mosquitos Vetores , Animais , Culex/virologia , Grécia , Flavivirus/genética , Flavivirus/isolamento & purificação , Flavivirus/classificação , Mosquitos Vetores/virologia , Reação em Cadeia da Polimerase em Tempo Real , Infecções por Flavivirus/virologia , Infecções por Flavivirus/veterinária , Infecções por Flavivirus/transmissão , RNA Viral/genética , RNA Viral/isolamento & purificaçãoRESUMO
Annexin A2 (ANXA2) is a multifaceted protein implicated in various stages of viral infections, particularly in envelope virus replication through mechanisms such as endocytosis and exocytosis. This study delves into the characterization and functional dynamics of duck ANXA2 (duANXA2). We successfully cloned the full-length coding sequence of duANXA2 and conducted a detailed structural analysis. The open reading frame (ORF) of duANXA2 is 1020 bp, encoding 339 amino acids and featuring 4 conserved domains. Phylogenetic tree analysis indicates that duANXA2 is most closely related to Gallus gallus, with significantly lesser homology to fish species. We evaluated the tissue-specific expression of duANXA2 in healthy ducks, noting its ubiquitous presence but varying expression levels across different organs, with notably high expression in the esophagus and immune organs. Upon infecting duck embryo fibroblast (DEF) cells with the duck Tembusu virus (DTMUV), a flavivirus causing ducks substantial mortality and a dramatic decline in egg production, we observed a pronounced upregulation of duANXA2. Functional assays demonstrated that overexpression of duANXA2 in DEF cells augments DTMUV replication, while its interference markedly reduces DTMUV replication. These findings underscore the role of duANXA2 as a facilitator of DTMUV replication, presenting it as a potential target for therapeutic intervention in managing DTMUV infections.
Assuntos
Anexina A2 , Proteínas Aviárias , Patos , Flavivirus , Filogenia , Doenças das Aves Domésticas , Replicação Viral , Animais , Patos/genética , Anexina A2/genética , Anexina A2/metabolismo , Doenças das Aves Domésticas/virologia , Doenças das Aves Domésticas/genética , Flavivirus/fisiologia , Flavivirus/genética , Proteínas Aviárias/genética , Proteínas Aviárias/metabolismo , Proteínas Aviárias/química , Clonagem Molecular , Infecções por Flavivirus/veterinária , Infecções por Flavivirus/virologia , Infecções por Flavivirus/genética , Sequência de Aminoácidos , Alinhamento de Sequência/veterináriaRESUMO
Usutu virus (USUV) is an emerging flavivirus that is maintained in an enzootic cycle with mosquitoes as vectors and birds as amplifying hosts. In Europe, the virus has caused mass mortality of wild birds, mainly among Common Blackbird (Turdus merula) populations. While mosquitoes are the primary vectors for USUV, Common Blackbirds and other avian species are exposed to other arthropod ectoparasites, such as ticks. It is unknown, however, if ticks can maintain and transmit USUV. We addressed this question using in vitro and in vivo experiments and field collected data. USUV replicated in IRE/CTVM19 Ixodes ricinus tick cells and in injected ticks. Moreover, I. ricinus nymphs acquired the virus via artificial membrane blood-feeding and maintained the virus for at least 70 days. Transstadial transmission of USUV from nymphs to adults was confirmed in 4.9% of the ticks. USUV disseminated from the midgut to the haemocoel, and was transmitted via the saliva of the tick during artificial membrane blood-feeding. We further explored the role of ticks by monitoring USUV in questing ticks and in ticks feeding on wild birds in the Netherlands between 2016 and 2019. In total, 622 wild birds and the Ixodes ticks they carried were tested for USUV RNA. Of these birds, 48 (7.7%) carried USUV-positive ticks. The presence of negative-sense USUV RNA in ticks, as confirmed via small RNA-sequencing, showed active virus replication. In contrast, we did not detect USUV in 15,381 questing ticks collected in 2017 and 2019. We conclude that I. ricinus can be infected with USUV and can transstadially and horizontally transmit USUV. However, in comparison to mosquito-borne transmission, the role of I. ricinus ticks in the epidemiology of USUV is expected to be minor.
Assuntos
Doenças das Aves , Infecções por Flavivirus , Flavivirus , Ixodes , Ninfa , Animais , Ixodes/virologia , Ixodes/fisiologia , Flavivirus/fisiologia , Flavivirus/genética , Infecções por Flavivirus/transmissão , Infecções por Flavivirus/veterinária , Infecções por Flavivirus/virologia , Ninfa/virologia , Doenças das Aves/virologia , Doenças das Aves/transmissão , Aves/virologia , Vetores Aracnídeos/virologia , Vetores Aracnídeos/fisiologia , Países Baixos , FemininoRESUMO
Usutu virus is an emerging pathogen transmitted by mosquitoes. Culex modestus mosquitoes are widespread in Europe, but their role in disease transmission is poorly understood. Recent data from a single infectious mosquito suggested that Culex modestus could be an unrecognized vector for Usutu virus. In this study, our aim was to corroborate this finding using a larger sample size. We collected immature Culex modestus from a reedbed pond in Flemish Brabant, Belgium, and reared them in the laboratory until the third generation. Adult females were then experimentally infected with Usutu virus in a blood meal and incubated at 25 °C for 14 days. The presence of Usutu virus in the saliva, head and body of each female was determined by plaque assay and quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). The transmission efficiency was 54% (n = 15/28), confirming that Belgian Culex modestus can experimentally transmit Usutu virus.
Assuntos
Culex , Infecções por Flavivirus , Flavivirus , Mosquitos Vetores , Animais , Culex/virologia , Feminino , Mosquitos Vetores/virologia , Flavivirus/genética , Flavivirus/fisiologia , Bélgica , Infecções por Flavivirus/transmissão , Infecções por Flavivirus/virologia , Saliva/virologiaRESUMO
Usutu virus (USUV), an arbovirus from the Flaviviridae family, genus Flavivirus, has recently gained increasing attention because of its potential for emergence. After his discovery in South Africa, USUV spread to other African countries, then emerged in Europe where it was responsible for epizootics. The virus has recently been found in Asia. USUV infection in humans is considered to be most often asymptomatic or to cause mild clinical signs. However, a few cases of neurological complications such as encephalitis or meningo-encephalitis have been reported in both immunocompromised and immunocompetent patients. USUV natural life cycle involves Culex mosquitoes as its main vector, and multiple bird species as natural viral reservoirs or amplifying hosts, humans and horses can be incidental hosts. Phylogenetic studies carried out showed eight lineages, showing an increasing genetic diversity for USUV. This work describes the development and validation of a novel whole-genome amplicon-based sequencing approach to Usutu virus. This study was carried out on different strains from Senegal and Italy. The new approach showed good coverage using samples derived from several vertebrate hosts and may be valuable for Usutu virus genomic surveillance to better understand the dynamics of evolution and transmission of the virus.
Assuntos
Infecções por Flavivirus , Flavivirus , Genoma Viral , Filogenia , Flavivirus/genética , Flavivirus/classificação , Flavivirus/isolamento & purificação , Animais , Infecções por Flavivirus/virologia , Infecções por Flavivirus/veterinária , Humanos , Senegal , Itália , Aves/virologia , RNA Viral/genética , Variação Genética , Culex/virologia , Sequenciamento Completo do Genoma , Cavalos/virologiaRESUMO
The genus Flavivirus comprises approximately 80 different viruses. Phylogenetic relationships among its members indicate a clear ecological separation between those viruses transmitted by mosquitoes, ticks, with no known vector, and insect-specific Flaviviruses. The diversity and phylogenetic relationships among insect-specific flaviviruses circulating in the central and northern regions of Argentina were studied by performing molecular detection and characterization of the NS5 protein gene in mosquitoes collected in Córdoba, Chaco and Tucumán provinces. Overall, 68 out of 1776 pools were positive. CxFV, KRV and CFAV circulate in the 3 studied provinces. Several mosquito species (Aedes aegypti, Culex bidens, Cx. dolosus, Cx. interfor, Cx. quinquefasciatus, Cx. saltanensis, Haemagogus spegazzini) were found infected. A wide circulation of CxFV was observed in the central-northern region of Argentina. CxFV strains detected in our study clustered with strains circulating in Santa Fe and Buenos Aires provinces (Argentina), and other countries such as Indonesia, Mexico, Uganda and Taiwan. The presence of these viruses in mosquitoes could play an important role from the public health perspective, because it has been shown that previous CxFV infection can increase or block the infection of the mosquito by other pathogenic flaviviruses.
Assuntos
Culicidae , Flavivirus , Mosquitos Vetores , Filogenia , Animais , Argentina , Flavivirus/classificação , Flavivirus/genética , Flavivirus/isolamento & purificação , Culicidae/virologia , Culicidae/classificação , Mosquitos Vetores/virologia , Mosquitos Vetores/classificaçãoRESUMO
Viral genetic diversity presents significant challenges in developing antivirals with broad-spectrum activity and high barriers to resistance. Here we report development of proteolysis targeting chimeras (PROTACs) targeting the dengue virus envelope (E) protein through coupling of known E fusion inhibitors to ligands of the CRL4CRBN E3 ubiquitin ligase. The resulting small molecules block viral entry through inhibition of E-mediated membrane fusion and interfere with viral particle production by depleting intracellular E in infected Huh 7.5 cells. This activity is retained in the presence of point mutations previously shown to confer partial resistance to the parental inhibitors due to decreased inhibitor-binding. The E PROTACs also exhibit broadened spectrum of activity compared to the parental E inhibitors against a panel of mosquito-borne flaviviruses. These findings encourage further exploration of targeted protein degradation as a differentiated and potentially advantageous modality for development of broad-spectrum direct-acting antivirals.
Assuntos
Antivirais , Vírus da Dengue , Flavivirus , Proteólise , Internalização do Vírus , Humanos , Proteólise/efeitos dos fármacos , Animais , Antivirais/farmacologia , Flavivirus/efeitos dos fármacos , Flavivirus/genética , Flavivirus/metabolismo , Internalização do Vírus/efeitos dos fármacos , Vírus da Dengue/efeitos dos fármacos , Vírus da Dengue/fisiologia , Vírus da Dengue/genética , Culicidae/virologia , Ubiquitina-Proteína Ligases/metabolismo , Proteínas do Envelope Viral/metabolismo , Linhagem CelularRESUMO
Newly emerging viruses, primarily zoonotic or vector-borne, pose a persistent threat to public health and have led to outbreaks of global concern [...].
Assuntos
Infecções por Alphavirus , Alphavirus , Infecções por Flavivirus , Flavivirus , Alphavirus/fisiologia , Alphavirus/genética , Humanos , Animais , Flavivirus/genética , Flavivirus/fisiologia , Infecções por Alphavirus/virologia , Infecções por Alphavirus/epidemiologia , Infecções por Flavivirus/virologia , Infecções por Flavivirus/epidemiologiaRESUMO
The Orthoflavivirus ilheusense (ILHV) is an arbovirus that was first isolated in Brazil in 1944 during an epidemiologic investigation of yellow fever. Is a member of the Flaviviridae family and it belongs to the antigenic complex of the Ntaya virus group. Psorophora ferox is the primary vector of ILHV and this study presents the isolation and phylogenetic analysis of ILHV in a pool of Ps. ferox collected in the state of Goiás in 2021. Viral isolation tests were performed on Vero cells and C6/36 clones. The indirect immunofluorescence test (IFI) was used to confirm the positivity of the sample. The positive sample underwent RT-qPCR, sequencing, and phylogenetic analysis. This is the first report of ILHV circulation in this municipality and presented close relationship between this isolate and another ILHV isolate collected in the city of Belém (PA).
Assuntos
Culicidae , Filogenia , Animais , Brasil , Células Vero , Culicidae/virologia , Chlorocebus aethiops , Flavivirus/genética , Flavivirus/isolamento & purificação , Flavivirus/classificação , Mosquitos Vetores/virologiaRESUMO
Zika and dengue virus nonstructural protein 5 antagonism of STAT2, a critical interferon signaling transcription factor, to suppress the host interferon response is required for viremia and pathogenesis in a vertebrate host. This affects viral species tropism, as mouse STAT2 resistance renders only immunocompromised or humanized STAT2 mice infectable. Here, we explore how STAT2 evolution impacts antagonism. By measuring the susceptibility of 38 diverse STAT2 proteins, we demonstrate that resistance arose numerous times in mammalian evolution. In four species, resistance requires distinct sets of multiple amino acid changes that often individually disrupt STAT2 signaling. This reflects an evolutionary ridge where progressive resistance is balanced by the need to maintain STAT2 function. Furthermore, resistance may come with a fitness cost, as resistance that arose early in lemur evolution was subsequently lost in some lemur lineages. These findings underscore that while it is possible to evolve resistance to antagonism, complex evolutionary trajectories are required to avoid detrimental host fitness consequences.