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A single-nucleus transcriptomic atlas of the adult Aedes aegypti mosquito.

The female Aedes aegypti mosquito's remarkable ability to hunt humans and transmit pathogens relies on her unique biology. Here, we present the Aedes aegypti Mosquito Cell Atlas, a comprehensive single-nucleus RNA sequencing dataset of more than 367,000 nuclei from 19 dissected tissues of adult female and male Aedes aegypti, providing cellular-level resolution of mosquito biology. We identify novel cell types and expand our understanding of sensory neuron organization of chemoreceptors to all sensory tissues. Our analysis uncovers male-specific cells and sexually dimorphic gene expression in the antenna and brain. In female mosquitoes, we find that glial cells in the brain, rather than neurons, undergo the most extensive transcriptional changes following blood feeding. Our findings provide insights into the cellular basis of mosquito behavior and sexual dimorphism. The Aedes aegypti Mosquito Cell Atlas resource enables systematic investigation of cell type-specific expression across all mosquito tissues.

Aedes aegypti

Fine-Scale Landscape Genomics Show Asymmetric Patterns of Gene Flow for the Invasive Mosquito Aedes albopictus.

Mosquito-borne viruses like dengue, Zika, and chikungunya pose increasing health risks in the United States due to the expanding range of Aedes albopictus, a highly invasive mosquito species that now has a global distribution. Aedes albopictus thrive in artificial containers associated with anthropogenic land use, allowing populations to reach high numbers in urban and suburban environments. While the global spread of Ae. albopictus has been well characterized, the effects of heterogeneous urban landscapes on dispersal and gene flow at fine spatial scales remain unclear. This study analyzed the genetic connectivity of Aedes albopictus populations collected in Wake County, North Carolina in 2018. We used single nucleotide polymorphisms (SNP) data from double-digest restriction-enzyme associated DNA sequencing (ddRADseq) and examined genetic connectivity through principal component analysis (PCA) and genetic network analysis. We then evaluated migration and source-sink dynamics using a Bayesian approach for SNP data (BA3-SNP). We found little evidence of genetic clustering or isolated populations of Ae. albopictus in Wake County, suggesting high gene flow between sites. Migration analysis demonstrated asymmetric gene flow from rural to urban regions within Wake County, with greater gene flow occurring between and within urban regions. These findings suggest that the pattern of gene flow of Ae. albopictus populations within local metropolitan areas may involve urban city centers serving as genetic sinks and surrounding suburban and rural regions serving as sources. This study highlights how heterogeneous landscapes shape mosquito population connectivity and migration at fine spatial scales, which is critical for informing vector control and public health intervention strategies.

Aedes albopictus

The piRNA pathway mediates transcriptional silencing of LTR retrotransposons in ovaries and somatic tissues of Aedes mosquitoes.

The PIWI-interacting RNA (piRNA) pathway preserves genomic integrity by suppressing transposable elements in animal germlines. Despite its well-established function in the animal germline, piRNAs and PIWI proteins are expressed in somatic tissues across arthropod species, and their functions outside the gonads remain poorly understood. Aedes albopictus mosquitoes express four PIWI genes, Piwi4, Piwi5, Piwi6, and Ago3, in both gonadal and somatic tissues. Here, we generated Piwi6 knockout (KO) Ae. albopictus cell lines and observed a substantial upregulation of long terminal repeat retrotransposons, including a full-length endogenous retrovirus that we named Aedes albopictus Endogenous Retrovirus-1 (AalERV1). Nascent RNA sequencing and Cleavage Under Targets and Tagmentation (CUT&Tag) analyses revealed that Piwi6 silences AalERV1 transcriptionally by guiding the deposition of the repressive H3K9me3 histone mark. Consistently, Piwi6 localized to both the cytoplasm and nucleus, with sequences in the intrinsically disordered region guiding nuclear translocation. Reintroduction of full-length GFP-Piwi6, but not a mutant GFP-Piwi6 defective in nuclear localization, rescued AalERV1 repression in Piwi6 KO cells. Importantly, Piwi6-mediated control of AalERV1 was recapitulated in vivo as Piwi6 knockdown increased AalERV1 expression in both ovaries and somatic tissues of Ae. albopictus mosquitoes. These results establish Aedes mosquitoes as a model to study nuclear PIWI functions and suggest that somatic piRNA-mediated transposon silencing is evolutionarily conserved across arthropod species.

Animals

Infection rate of Aedes aegypti mosquitoes with dengue virus depends on the interaction between temperature and mosquito genotype.

Dengue fever is the most prevalent arthropod-transmitted viral disease worldwide, with endemic transmission restricted to tropical and subtropical regions of different temperature profiles. Temperature is epidemiologically relevant because it affects dengue infection rates in Aedes aegypti mosquitoes, the major vector of the dengue virus (DENV). Aedes aegypti populations are also known to vary in competence for different DENV genotypes. We assessed the effects of mosquito and virus genotype on DENV infection in the context of temperature by challenging Ae. aegypti from two locations in Vietnam, which differ in temperature regimes, with two isolates of DENV-2 collected from the same two localities, followed by incubation at 25, 27 or 32°C for 10 days. Genotyping of the mosquito populations and virus isolates confirmed that each group was genetically distinct. Extrinsic incubation temperature (EIT) and DENV-2 genotype had a direct effect on the infection rate, consistent with previous studies. However, our results show that the EIT impacts the infection rate differently in each mosquito population, indicating a genotype by environment interaction. These results suggest that the magnitude of DENV epidemics may not only depend on the virus and mosquito genotypes present, but also on how they interact with local temperature. This information should be considered when estimating vector competence of local and introduced mosquito populations during disease risk evaluation.

Aedes

Remodeling of host lipid metabolism by Wolbachia strain wAlbB is associated with lipid accumulation and cardiolipin dysregulation in the Aedes aegypti fat body.

BACKGROUND: The intracellular symbiont Wolbachia, particularly the wAlbB strain, is a promising biocontrol agent against mosquito-borne diseases. Although Wolbachia infection is known to perturb host metabolism, the underlying mechanisms, especially those related to lipid metabolism, remain poorly understood. METHODS: We performed an integrated multi-level analysis of the Aedes aegypti fat body in uninfected and wAlbB-infected mosquitoes, combining histology, biochemistry, untargeted liquid chromatography-mass spectrometry (LC-MS) lipidomics, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis, reverse transcription quantitative PCR of key metabolic genes, and quantification of acetyl-coenzyme A (acetyl-CoA) and reduced nicotinamide adenine dinucleotide (NADH) levels. RESULTS: wAlbB infection increased fat body wet weight and thickness, accompanied by accumulation of triglyceride and of lipid droplets. Lipidomic analysis further revealed extensive lipidome remodeling, with elevated free fatty acid, diglyceride, and triglyceride, but broad depletion of glycerophospholipids, particularly cardiolipin. These changes were supported by transcriptional alterations: upregulation of fatty acid synthase 1 and glycerol-3-phosphate acyltransferase 1, and downregulation of adipose triglyceride lipase and carnitine palmitoyltransferase 1. Cardiolipin depletion correlated with downregulation of genes involved in its synthesis and remodeling, including phosphatidylglycerophosphate synthase and calcium-independent phospholipase A2γ. These lipid changes were also associated with accumulation of acetyl-CoA and NADH. CONCLUSIONS: Our findings suggest that wAlbB infection is associated with extensive lipid metabolic remodeling in the Aedes aegypti fat body, characterized by accumulation of neutral lipids and cardiolipin depletion, accompanied by transcriptional remodeling of key metabolic enzymes. This study establishes the fat body as a primary tissue-level hub for Wolbachia-associated lipid remodeling and provides a foundational framework for future mechanistic investigations into host-symbiont metabolic interactions.

Animals

MDV-like endogenous viral elements act as immune rheostats in Aedes cells by modulating defensin A-mediated responses to arboviruses.

Mosquito cell lines are essential tools for arbovirus research. Endogenous viral elements (EVEs) are prevalent in mosquito genomes, yet their functional effects on host immune responses remain unclear, potentially complicating experimental interpretations. In this study, we systematically characterized endogenous mosquito densovirus-like elements (EMLs) within the Aedes aegypti Aag2 cell line and found that these endogenous EMLs are transcriptionally active but translationally defective. The silencing of EML transcripts significantly diminished the replication of Zika virus (ZIKV), Japanese encephalitis virus (JEV), and chikungunya virus (CHIKV), while transiently increasing dengue virus 2 (DENV-2), thereby indicating a virus-dependent regulatory mechanism. Mechanistically, RNA sequencing after EML interference, alongside plasmid-based mimic expression, demonstrated that EML transcripts downregulate defensin A, an antimicrobial peptide produced by mosquitoes. Functional assays using synthetic defensin A showed that this peptide differentially regulates arboviral infection. Binding assays and structural modeling further supported its interaction with viral envelope proteins, while stage-restricted infection assays revealed distinct stages of action: defensin A enhanced adsorption of ZIKV, JEV, and CHIKV, but did not promote DENV-2 adsorption or entry, and instead reduced DENV-2 RNA accumulation at the post-entry replication stage. Our findings highlight a previously unrecognized role of densovirus-derived EVEs in mosquito innate immunity, extending their functional scope from the well-established PIWI-interacting RNA-mediated antiviral defense to the regulation of antimicrobial peptide-associated immune pathways. These findings emphasize the necessity of accounting for EVE activity when analyzing data derived from mosquito cell lines, and suggest that related EVE-mediated immune regulation may contribute to arbovirus dynamics in mosquitoes.IMPORTANCEMosquito-borne viruses such as dengue, Zika, Japanese encephalitis, and chikungunya continue to threaten human health worldwide. Laboratory studies often use Aedes aegypti cell lines to investigate how these viruses interact with their mosquito hosts. Here, we show that the genomes of these cells contain endogenous viral elements derived from mosquito densoviruses. Far from being inert fossils, these sequences are transcriptionally active and regulate mosquito immunity by suppressing the antimicrobial peptide defensin A. This immune modulation influences the replication of different arboviruses in opposite ways, enhancing some while restricting others. Our findings reveal that integrated viral elements can shape the outcome of arbovirus infection, with important implications for interpreting mosquito cell culture experiments and for evaluating endogenous viral element-mediated immune regulation in mosquito-virus interactions.

Aag2 cell

Expansive and Diverse Phenotypic Landscape of Field Aedes aegypti (Diptera: Culicidae) Larvae with Differential Susceptibility to Temephos: Beyond Metabolic Detoxification.

Arboviruses including dengue, Zika, and chikungunya are amongst the most significant public health concerns worldwide. Arbovirus control relies on the use of insecticides to control the vector mosquito Aedes aegypti (Linnaeus), the success of which is threatened by widespread insecticide resistance. The work presented here profiled the gene expression of Ae. aegypti larvae from field populations of Ae. aegypti with differential susceptibility to temephos originating from two Colombian urban locations, Bello and Cúcuta, previously reported to have distinctive disease incidence, socioeconomics, and climate. We demonstrated that an exclusive field-to-lab (Ae. aegypti strain New Orleans) comparison generates an over estimation of differential gene expression (DGE) and that the inclusion of a geographically relevant field control yields a more discrete, and likely, more specific set of genes. The composition of the obtained DGE profiles is varied, with commonly reported resistance associated genes including detoxifying enzymes having only a small representation. We identify cuticle biosynthesis, ion exchange homeostasis, an extensive number of long noncoding RNAs, and chromatin modelling among the differentially expressed genes in field resistant Ae. aegypti larvae. It was also shown that temephos resistant larvae undertake further gene expression responses when temporarily exposed to temephos. The results from the sampling triangulation approach here contribute a discrete DGE profiling with reduced noise that permitted the observation of a greater gene diversity, increasing the number of potential targets for the control of insecticide resistant mosquitoes and widening our knowledge base on the complex phenotypic network of the Ae. aegypti response to insecticides.

Aedes

Autodissemination stations suppress Aedes notoscriptus mosquitoes and reduce Buruli ulcer risk in urban Australia: a randomized controlled field trial.

Aedes notoscriptus are mosquito vectors implicated in transmission of Mycobacterium ulcerans. This bacterium causes a destructive infection of skin and soft tissue called Buruli ulcer. Here we ran a randomized controlled trial in an urban Buruli ulcer endemic area in Melbourne, Australia to test whether autodissemination mosquito control stations, containing pyriproxyfen (larvicide) and Beauveria bassiana (entomopathogenic fungus), suppress Ae. notoscriptus populations. Six geographic areas each received 100 autodissemination stations for 8 weeks, and six control areas received no stations between 25 January 2024 and 21 March 2024. The primary outcome measure was mosquito population numbers. After the trial, there was a 70% average reduction in mosquito egg counts among the six intervention areas compared to control areas (P = 0.0076). In an ad hoc analysis, we then explored human Buruli ulcer notifications in treatment and control areas. After accounting for the 4.8-month mean incubation period, there was an 83% reduction in infection likelihood coinciding with peak intervention effect (intervention zones 1 case, control zones 6 cases, incidence ratio rate 0.167, 95% CI 0.0026-1.054, P = 0.047). The effect was not observed during the same time period in the year previous or following 2024, when no interventions were undertaken. A strong correlation (R2 = 0.85) was observed between decreased disease risk and mosquito suppression. These data show that autodissemination traps can effectively lower urban mosquito populations and reduce the threat of Buruli ulcer in humans.

Animals

Knockdown-resistance (kdr) mutations in Indian Aedes aegypti populations: Lack of recombination among haplotypes bearing V1016G, F1534C, and F1534L kdr alleles.

BACKGROUND: Knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC) gene are a key mechanism of insecticide resistance in mosquitoes. In Asian Aedes aegypti populations two main VGSC haplogroups with kdr mutations have been identified: one carrying the F1534C mutation and another with V1016G and/or S989P mutations. Previous functional studies have demonstrated that these three mutations on a single haplotype confer up to a 1100-fold increase in pyrethroid resistance, underscoring the importance of monitoring these triple mutations in distinct populations. This study investigates the prevalence of kdr mutations in Indian populations and explores the linkage association between these mutations and two distinct conserved types of introns located between exons 20 and 21. METHODS: Ae. aegypti specimens collected from eight different locations were genotyped for kdr alleles and intron (between exons 20 and 21) haplotypes using PCR-based assays. Representative samples underwent DNA sequencing of VGSC regions. RESULTS: Five kdr mutations namely S989P, V1016G, T1520I, F1534C, and F1534L were identified, each exhibiting varying distribution and frequencies across different geographical regions. Two distinct and stably-diverged intron haplotypes, designated as intron-A and intron-B, were identified between exons 20 and 21. Seven haplotypes, including two wild-type variants, were observed among Indian populations. The kdr-bearing haplotypes can be classified into three distinct haplogroups: haplogroup G (V1016G with/or without S989P and with intron-A), haplogroup L (F1534L and intron-A), and haplogroup C (F1534C with/or without T1520I and with intron-B). Importantly, no evidence of recombination within Indian populations was detected among these three haplogroups. CONCLUSIONS: Five kdr mutations were identified in the VGSC of Indian Ae. aegypti populations, each showing a definitive linkage with one of the two types of intron haplotypes. The lack of recombination among haplogroups bearing 1016G with 989P, 1534C and 1534L mutations suggests that the most potent insecticide resistance haplotype, bearing the triple kdr mutation, is currently absent. This finding has significant operational implications, as it may indicate that current vector control measures remain effective against these populations, potentially delaying the emergence of highly resistant phenotypes.

Animals

Population genomics of Aedes albopictus across remote Pacific islands for genetic biocontrol considerations.

Remote Pacific islands (RPI) are characterized by ecological isolation, diverse endemic species, and vulnerability to invasive organisms due to globalization-driven connectivity. Among these species, Aedes albopictus, a highly invasive vector of flaviviruses, has spread extensively across the RPI via human-mediated dispersal, posing significant health and economic burdens. While the population structure and the degree of gene flow between mosquito populations can inform the dispersal pathways critical for disease vector management, the population genetics of Ae. albopictus in Northern RPI remains understudied. The present work investigated the population structure and connectivity of Ae. albopictus populations from Guam, Hawaiian Islands, and the Republic of the Marshall Islands (RMI) to inform disease and vector-based biosecurity risks and develop targeted management strategies. This is the first assessment to develop and analyze whole genome sequences of Ae. albopictus for RPI, enabling more accurate estimates of differentiation, admixture, and ancestry. We found distinct genetic clustering between regions, distinct ancestry of populations across RPI, and potential invasions that originated from Hawaii and spread into the RMI, and invasions from North America that spread to Guam. These findings can inform biosecurity protocols to limit the invasion of Ae. albopictus and their associated diseases within Hawaii and around the Pacific. Given the significant degree of genetic differentiation, we found between islets, islands, and regions, the genome data from this study can be used to enable the development of locally confined geographically isolated gene drives. These drives may be used to prevent and control outbreaks of dengue, chikungunya, and Zika, diseases that have had devastating consequences in these remote island communities.

Animals

Emergence and phylogeography of the dengue vector Aedes aegypti in Southeastern Iran.

BACKGROUND: Aedes (Stegomyia) aegypti (Linnaeus) is the primary vector of dengue, chikungunya, Zika, and yellow fever viruses. Its recent detection in southeastern Iran raises public health concerns about arbovirus spread to new regions. This study provides the first genetic and phylogeographic analysis of Ae. aegypti populations from Sistan and Baluchistan Province (SBP), Iran, to infer their origin and invasion pathways. METHODS: Mitochondrial COI and ND4 genes were analysed in newly collected Ae. aegypti specimens from border areas, ports, and urban centres of SBP. Haplotype network analyses were constructed using the TCS method in PopART, and phylogenetic analyses were conducted using global reference sequences. RESULTS: Iranian specimens comprised 7 COI haplotypes (n = 18) and 10 ND4 haplotypes (n = 17). COI phylogeny placed Iranian specimens into two main clades, while ND4 analysis distributed them across several derived clades, mostly clustering with lineages from Latin America (Brazil, Mexico) or Africa. One Iranian specimen showed a close relationship with a Saudi Arabian sequence (bootstrap: 98%) near the basal region. Combined COI + ND4 analysis revealed a monophyletic clade of Iranian specimens with a Sri Lankan specimen, distinct from other global lineages. The global COI network (n = 47) showed a star-like topology with a dominant haplotype 1 shared among 10 Iranian specimens. The ND4 network (n = 31) revealed a complex topology with 18 haplotypes, where a Saudi Arabian and one Iranian specimen (~30 mutational steps) possibly represented the peripheral root. CONCLUSIONS: Detection of diverse Ae. aegypti clades confirm establishment of this vector in southeastern Iran. Results support multiple introductions and genetic connectivity with Latin America, Africa, and South Asia, pointing to an emerging invasion corridor. Continued genomic surveillance and integrated vector monitoring are urgently needed to guide prevention strategies.

Animals

Comet assay analysis of multigenerational genomic instability (F0-F2) in Aedes aegypti exposed to gamma radiation in Sterile Insect Technique.

The use of irradiation in the Sterile Insect Technique (SIT) is a sustainable and environmentally friendly strategy for controlling Aedes aegypti populations by the release of sterile males. However, the potential toxic effects of radiation on mosquito genetic material, as well as the heritability of such damage, remain insufficiently understood. In this study, we evaluated gamma radiation-induced DNA damage (20, 30, 40, and 50 Gy) in male pupae (F0 generation) and assessed the persistence of these effects in subsequent generations (F1 and F2) using the comet assay in hemocytes. In the parental generation, a significant dose-response relationship was observed, with increasing radiation doses associated with higher damage index and damage frequency (p < 0.05). In the F1 generation, both larvae and adults exhibited significantly greater DNA damage than the control group, particularly at doses of 30 and 40 Gy, supporting the inheritance of radiation-induced genomic instability. In the F2 generation, genotoxic effects were attenuated, although residual damage remained detectable in adults, suggesting partial recovery of genomic stability, possibly influenced by DNA repair mechanisms and/or selective pressures. No viable offspring were obtained at 50 Gy, confirming the sterilizing efficacy of higher doses. Integration of comet assay results with micronucleus data and reproductive parameters reinforces the association between DNA damage, mutagenic effects, and reduced fertility. These findings indicate that radiation-induced genotoxic effects may persist beyond the irradiated generation but tend to decline across generations. Overall, this study provides insights into the balance between achieving sterility and preserving biological quality in SIT programs, contributing to optimizing radiation doses and enhancing the safety and efficacy of vector control strategies.

Comet assay

Unveiling crosstalk regulations within the polyamine pathway and between polyamine and purine pathways in Aedes aegypti females.

We previously demonstrated that ornithine decarboxylase (ODC) deficiency critically impairs nitrogen metabolism and survival in Aedes aegypti. To further examine the role of the polyamine pathway in Ae. aegypti nitrogen metabolism, we evaluated the expression of three additional genes encoding proteins involved in the biosynthetic pathway: S-adenosylmethionine decarboxylase, spermidine synthase (SdS), spermine synthase (SmS), and seven genes encoding proteins involved in the catabolic pathway in fat body, midgut and Malpighian tubules by qPCR. Distinct transcriptional profiles were observed in mosquito tissues during the first gonotrophic cycle. SdS and SmS showed a differential protein expression pattern in fat body of sugar- and blood-fed mosquitoes. Genetic silencing of SdS, SmS or SdS and SmS by RNA interference (RNAi) decreased female survival. Mosquitoes with SdS or SmS deficiency exhibited a reduction of 5G1 trypsin level in the midgut at 24&#x202f;h post-blood meal (PBM) , a delay in blood digestion, and a decrease in uric acid concentration in the excreta at 48&#x202f;h PBM. RNAi-mediated SdS knockdown also caused a decrease in SmS protein level and vice-versa, RNAi-driven SmS deficiency resulted in a decrease in SdS protein abundance. Notably, ODC knockdown reduced SdS, SmS, xanthine dehydrogenase-1 protein levels, and decreased specific metabolite concentrations in fat body at 24&#x202f;h PBM. In addition, RNAi-mediated ODC, SdS and SmS knockdown impacted transcript levels of genes involved in polyamine and purine pathways in fat body at 24&#x202f;h PBM. Our findings uncover unique crosstalk regulations within the polyamine pathway and between polyamine and purine pathways.

Ammonia metabolism

Altered histone modifications in Aedes aegypti following Rift Valley fever virus exposure.

When arthropod-borne viruses (arboviruses) are delivered to vector mosquitoes in an infectious bloodmeal, viral components interact with host proteins to hijack cells and initiate replication. The extent to which arbovirus infection alters mosquito host transcriptional and genomic regulatory processes is currently unknown. We hypothesized that histone modifications would be altered in mosquitoes exposed to Rift Valley fever virus (RVFV MP12, Phlebovirus riftense, family Phleboviridae). We interrogated transcriptome and chromatin landscapes in Aedes aegypti midguts by performing Cleavage Under Targets and Release Using Nuclease (CUT&RUN), using H3K27ac and H3K9me3 marks. Altered H3K27ac marks were identified following RVFV MP12 exposure, as well as upon bloodfeeding alone. It took several days for differential H3K27ac marks to be associated with differentially expressed genes (DEGs) in RVFV-exposed midguts. H3K27ac peaks showed progressive depletion as infection progressed. Gene set enrichment analysis revealed that immune response transcripts were enriched at 1 and 3 dpf (days post-feeding) but depleted by 7 dpf. Hedgehog/Gli (glioma-associated oncogene homolog) signaling pathway transcripts were depleted, indicating possible viral manipulation of cellular polarization. Moreover, at 7 dpf, 7 of 102 DEGs were proximal to differentially acetylated sites in a pattern expected to favor viral propagation. However, one transcript coding for an antiviral effector (LysM-TLDc domain protein) showed significant depletion of both H3K9me3 and H3K27ac marks. Analysis of midguts after a non-infectious bloodmeal versus sugar-fed controls revealed global changes to H3K27ac and H3K9me3 marks during and following the period of bloodmeal digestion. Differential H3K27ac marks were proximal to one quarter of all DEGs at 1 dpf, consistent with an important role of H3K27ac in bloodmeal digestion. These results demonstrate that H3K27ac and H3K9me3 patterns are altered upon virus exposure in a complex interplay that favors viral replication but is also countered by host responses to limit replication.

ChIP-Seq

Identification of an unannotated early embryonic single-minded transcript in the yellow fever mosquito Aedes aegypti.

The yellow fever mosquito, Aedes aegypti , is a cosmopolitan species that serves as the vector of multiple disease causing agents including dengue, chikungunya, Zika, and yellow fever viruses. The genome of Ae. aegypti has been characterized at the chromosome level, but further manual refinement is required for genes and isoforms with transient expression or low abundance. Here we report on the identification of an early embryonic transcript for the single-minded (sim ) gene in Ae. aegypti , and present the putative promoter for the transcript. The identification of an early-driven transcript is consistent with the annotation for sim in Drosophila melanogaster.

Journal Article

Overview of Chikungunya Virus Epidemiology, Biology, and Pathogenesis.

Chikungunya virus (CHIKV), an arthropod-borne alphavirus within the Togaviridae family, is transmitted primarily by Aedes aegypti and Aedes albopictus. The virus causes an acute febrile illness characterized by severe, often bilateral polyarthralgia, with potential progression to chronic musculoskeletal pain and rare systemic complications involving cardiovascular and neurological systems. CHIKV exhibits a spherical, enveloped virion (~70&#x2009;nm) with T&#x2009;=&#x2009;4 icosahedral symmetry, incorporating E1/E2 glycoprotein heterodimers that mediate receptor binding and membrane fusion. Its positive-sense RNA genome (~11.8&#x2009;kb) encodes nonstructural proteins for replication and structural proteins for virion assembly. Replication occurs in cytoplasmic spherules, involving synthesis of genomic and subgenomic RNAs, followed by glycoprotein maturation and budding at the plasma membrane. Epidemiologically, CHIKV has expanded beyond Africa and Asia, with major outbreaks driven by adaptive mutations enhancing transmission via A. albopictus. Since introduction to the Americas in 2013, the global incidence remains high, with >180,000 confirmed cases reported in 2025. Preventive strategies rely on vector control and vaccination; VLP-based vaccines (e.g., Vimkunya) show promise, while live-attenuated formulations face safety concerns. No licensed antivirals exist; current management is supportive, though investigational therapies targeting viral replication and immune modulation are under development.

Chikungunya virus

Optimized Amplicon Strategy for Long-Read Sequencing of the Chikungunya Virus Genome.

Chikungunya virus (CHIKV) is a positive-sense RNA alphavirus transmitted to humans primarily by Aedes aegypti and Aedes albopictus mosquitoes. Its global circulation and significant public health impact underscore the need to better understand the molecular mechanisms driving CHIKV pathogenesis and transmission. Although robust molecular biology methods exist for CHIKV genome sequencing, a major limitation for surveillance and research is the inability to determine whether two nucleotide variations co-occur within the same viral genome when they are separated beyond the span of typical short-read designs. Here, we describe an optimized approach for processing CHIKV RNA samples that generates large amplicons suitable for long-read nanopore sequencing. This protocol enables amplification of the complete CHIKV genome in only two or three amplicons and facilitates detection of co-occurring nucleotide variations across 4-7.5&#x2009;kb within the same molecule, thereby simplifying sequencing workflows and improving resolution in studies of viral evolution.

Chikungunya virus

Amino Acid Substitutions in the Na+/K+-ATPase May Contribute to Salinity Tolerance in Insects.

Environmental salinity levels vary naturally across terrestrial ecosystems but can be heightened locally by coastal proximity and desertification as well as human activities such as road salt application and agriculture. Since salt is essential for many physiological processes in insects, rising environmental sodium concentrations may drive behavioral changes, where insects select environments and food sources with suitable sodium levels, or evolutionary changes in constitutive or plastic physiological mechanisms to process salt, potentially altering ecological dynamics and species interactions.Numerous hematophagous (blood feeding) insects such as the yellow-fever mosquito Aedes aeqypti are known to be able to breed in relatively saline environments. Among phytophagous (plant feeding) insects, grasshoppers can be important herbivores in arid and coastal salt-affected regions, whereas the monarch butterfly (Danaus plexippus) appears to perform relatively well on milkweed host plants growing in roadsides influenced by salt runoff. Several of these insects share a common trait: amino acid substitutions in the first extracellular loop of the Na+/K+-ATPase (NKA), a sodium pump crucial for maintaining ion balance. For the monarch these substitutions confer resistance to toxic cardenolides from milkweeds, but it is unclear whether NKA substitutions may influence salt tolerance.Here, we investigate whether the NKA substitutions found in these insects may contribute to salt tolerance using gene-edited Drosophila melanogaster mutant strains as models. We show that flies with substitution Q111L (found in Aedes mosquitoes) or a combination of Q111L and A119S (found in grasshoppers) exhibited greater salt tolerance, whereas flies carrying the combination of substitutions found in the monarch (Q111V, A119S, and N122H) did not.Our results suggest that the monarch may rely on alternate mechanisms for salt tolerance and that its NKA substitutions are important primarily for cardenolide resistance. However, substitution Q111L and the combination of Q111L and A119S may be relevant for salt tolerance in a variety of insects. Uncovering mechanisms of salt tolerance enhances our understanding of species distributions, ecological interactions, and evolutionary physiology in response to changing environmental salinity levels.

Journal Article