Episodios

  • Greenland Mosquito Virome: Arctic Aedes Uniqueness (May 2025)

    Greenland Mosquito Virome: Arctic Aedes Uniqueness (May 2025)
    May 30 2025
    Briefing Document: Unique Virome of Arctic Mosquitoes in GreenlandSource: https://doi.org/10.1038/s41598-025-01086-z: "Metagenomic analysis of mosquitoes from Kangerlussuaq, Greenland reveals a unique virome" by Schilling, Jagdev, Thomas, & Johnson (2025). Date: Received - 17 January 2025 | Accepted - 02 May 2025 | Published - 17 May 2025Subject: Metagenomic analysis of mosquito viromes in Kangerlussuaq, Greenland and implications in the context of climate change.Summary: This study provides the first metagenomic analysis of the virome of two prevalent Arctic mosquito species, Aedes impiger and Aedes nigripes, sampled near Kangerlussuaq, Greenland. The research employed next-generation sequencing (NGS) to identify viruses present in pooled mosquito samples collected in July 2022 and July 2023. The findings reveal a diverse and, importantly, a unique virome in these Arctic mosquitoes compared to other Aedes species. The study highlights the critical need to understand these viromes in light of climate change, which is significantly impacting Arctic ecosystems and potentially increasing the risk of vector-borne disease emergence and spread.Key Findings and Themes:Dominance of Aedes impiger: Contrary to previous assumptions that Aedes nigripes was the sole mosquito species in western Greenland, this study found Aedes impiger to be the predominant species collected at the Kangerlussuaq site.Fact: "Where a definitive identification could be made, A. impiger was the most frequently sampled mosquito at the Kangerlussuaq site."Fact: In 2023, "49 mosquitoes were identified as A. impiger (70%) and 16 as A. nigripes (23%)."Novel and Diverse Arctic Mosquito Virome: Metagenomic analysis identified a range of RNA viruses belonging to various families in both Aedes impiger and Aedes nigripes. Many of these viruses are novel and exhibit low sequence identity (sometimes as low as 34% at the amino acid level) when compared to previously published virus sequences from other mosquito species.Quote: "Metagenomic analysis of RNA extracted from species pools detected a number of novel RNA viruses belonging to a range of different virus families, including Flaviviridae, Orthomyxoviridae, Bunyavirales, Totiviridae and Rhabdoviridae."Quote: "However, the sequence identities when compared to previously published, were as low as 34% at the amino acid level."Fact: "Within the family of Flaviviridae, two novel flavi-like virus sequences were identified, with their polyproteins displaying 35% similarity to the nearest published polyprotein..."Fact: "Similarly, two novel orthomyxo-like sequences were identified within the family of Orthomoyxoviridae... Their nucleoprotein comprised only 36% identity to that of Byreska virus..."Fact: "Within the order of Bunyavirales, we discovered two novel phasiviruses as well as two novel phasmaviruses."Uniqueness of the Arctic Mosquito Virome: A significant finding is the distinct virome of Aedes impiger and Aedes nigripes compared to other Aedes species, particularly Aedes aegypti, which has the most well-characterized virome. Only a small percentage of the identified viruses overlapped with those found in other Aedes species.Quote: "To emphasize the uniqueness of the virome of A. impiger and A. nigripes, we compared our findings to a database of viruses published for other Aedes species... The heatmap... reveals that the majority of sequences derived from Greenland mosquitoes were unique to A. impiger and A. nigripes..."Fact: "...only 36 (of a total of 94, 38%) assigned viruses overlapping with viruses published for other Aedes spp."Fact: "Only 22 (23%) overlapped with Aedes aegypti..."Quote: "This makes the virome composition of A. cantans the most similar published virome composition to that of the mosquitoes we sampled near Kangerlussuaq."Influence of Climate Change on Arctic Vector Ecology: The study explicitly links its findings to the dramatic effects of climate change on Arctic ecosystems, including the potential for shifts in vector distribution and an increased likelihood of vector-borne disease emergence in previously unaffected areas.Quote: "Climate change is dramatically affecting vector ecology in extreme environments such as the Arctic."Quote: "Global changes in climate are causing a shift in the distribution of vectors and increasing the likelihood of vector-borne disease outbreaks in regions that have not experienced such disease emergence."Quote: "With rapid environmental change, and warming at twice the global average the ecology of Arctic insects will be dramatically affected."Potential for Zoonotic Transmission Risk: While the detected viruses are likely insect-specific, the study highlights the potential for Aedes impiger and Aedes nigripes to replicate viruses belonging to families with known zoonotic potential. The documented human feeding behavior of Aedes impiger further underscores this risk.Quote: "Our findings further support the capability of A. nigripes and A. ...
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  • Novel Quinolones Counteract Insecticide Resistance in Malaria Vectors (May 2025)

    Novel Quinolones Counteract Insecticide Resistance in Malaria Vectors (May 2025)
    May 30 2025
    BRIEFING DOCUMENT: Novel Approach to Malaria Control Targeting Mosquito-Stage Plasmodium ParasitesDate: Received - 29 March 2025 | Accepted - 17 April 2025 | Published - 21 May 2025Source: Excerpts from "In vivo screen of Plasmodium targets for mosquito-based malaria control" by Probst et al. (Published online xx xx xxxx, Nature) https://doi.org/10.1038/s41586-025-09039-2Subject: Development and testing of novel antiparasitic compounds for incorporation into mosquito bed nets to combat insecticide resistance and reduce malaria transmission.Summary:This research presents a promising new strategy for malaria control by targeting the Plasmodium falciparum parasite directly within its mosquito vector (Anopheles species). Recognizing the growing challenge of insecticide resistance in mosquitoes, the study explores the potential of incorporating antiparasitic compounds into long-lasting insecticide-treated nets (LLINs). The authors performed an in vivo screen of 81 compounds, identifying 22 active against mosquito-stage parasites. Notably, endochin-like quinolones (ELQs) targeting the parasite's cytochrome bc1 complex (CytB) showed high potency and were further optimized through medicinal chemistry. Two lead ELQ compounds, ELQ-453 and ELQ-613, demonstrated potent, long-lasting activity when incorporated into bed net-like materials, including in insecticide-resistant mosquitoes. The study also highlights the potential of a dual-target strategy using a combination of Qo-site and Qi-site ELQ inhibitors to reduce the risk of resistance, as CytB mutants show impaired development in mosquitoes. This approach offers a complementary tool to existing malaria control strategies, particularly in areas with high insecticide resistance.Key Themes and Important Ideas/Facts:Malaria Burden and the Challenge of Insecticide Resistance:Malaria deaths have stalled in recent years, with an estimated 263 million cases and 597,000 deaths in 2023.Vector control, particularly LLINs, has been crucial in reducing malaria prevalence, but widespread insecticide resistance in Anopheles vectors is jeopardizing their effectiveness."The decline in malaria deaths has recently stalled owing to several factors, including the widespread resistance of Anopheles vectors to the insecticides used in long-lasting insecticide-treated nets (LLINs)..."Targeting Mosquito-Stage Parasites as a Mitigation Strategy:Directly killing parasites during their mosquito-stage development by incorporating antiparasitic compounds into LLINs can prevent onward transmission, even if insecticides lose efficacy.This strategy avoids conferring fitness costs or selective pressure on the mosquito, thus preventing vector resistance to the antiparasitic compound."Interventions that directly target parasites in the mosquito represent a promising approach to disrupt parasite transmission and to reduce malaria burden...""Of note, the use of a Plasmodium-specific compound would not confer any fitness cost or selective pressure to the anopheline mosquito, which therefore avoids potential development of resistance by the vector."In Vivo Compound Screening and Identification of Key Targets:An in vivo screen of 81 antiplasmodial compounds with diverse modes of action was performed in Anopheles gambiae mosquitoes.22 compounds spanning seven distinct P. falciparum targets significantly reduced parasite infection (oocyst prevalence) in the mosquito midgut.Key identified targets included the ubiquinol oxidation (Qo) and ubiquinone reduction (Qi) sites of the P. falciparum cytochrome bc1 complex (CytB), the sodium-proton antiporter P-type ATPase 4 (ATP4), and eukaryotic elongation factor 2 (EF2)."This screen ultimately identified 22 compounds that significantly reduced parasite infection, and these compounds spanned seven P. falciparum targets..."Endochin-Like Quinolones (ELQs) as Lead Compounds:Endochin-like quinolones (ELQs) targeting CytB were among the most effective compounds in the topical screen.ELQ-456 (targeting the CytB Qo-site) completely inhibited infection in topical applications.ELQ-331 (targeting the CytB Qi-site) strongly reduced infection prevalence.Medicinal chemistry was used to improve the antiparasitic activity of ELQ hits, particularly for uptake via tarsal contact (mosquito legs).Tarsal Contact Activity and the Importance of Compound Structure:Tarsal contact assays, mimicking mosquito interaction with treated surfaces like bed nets, showed that most compounds active in topical application were inactive.Only ELQ-456 initially showed significant activity in tarsal contact assays.Modifications to the ELQ structure significantly enhanced tarsal-based efficacy. ELQ-453 (Qo-site inhibitor) and ELQ-613 (Qi-site inhibitor), with specific alkyl chain lengths, demonstrated potent activity after tarsal contact."Of the 13 compounds we tested in tarsal-contact assays, only our most potent hit in the topical screen, ELQ-456 (CytB Qo-site inhibitor) reduced infection (69.5% ...
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  • Blocking Malaria Transmission with PfPIMMS43 Nanobodies (April 2025)

    Blocking Malaria Transmission with PfPIMMS43 Nanobodies (April 2025)
    May 3 2025
    Briefing Document: Nanobody-Mediated Blocking of Malaria Transmission Targeting PfPIMMS43Source: Excerpts from "s42003-025-08033-8.pdf" (A Nature Portfolio journal; https://doi.org/10.1038/s42003-025-08033-8) Authors: Chiamaka Valerie Ukegbu, et al. Date: Received - 04 December 2024 | Accepted - 02 April 2025 | Published - 30 April 2025Executive Summary:This study explores a novel strategy to block malaria transmission by targeting the Plasmodium falciparum protein PfPIMMS43 using single-domain VHH antibodies, also known as nanobodies. PfPIMMS43 is a critical surface protein for the parasite's development within the mosquito, specifically during the transition from ookinete to oocyst, and aids in evading the mosquito's immune response. Building on previous research demonstrating the potential of polyclonal antibodies against PfPIMMS43, this study successfully developed and characterized high-affinity nanobodies derived from llamas. These nanobodies were shown to significantly reduce both the intensity and prevalence of P. falciparum infection in Anopheles mosquitoes using both laboratory and field strains of the parasite. The study mapped the binding epitopes of the nanobodies to conserved regions in the second half of PfPIMMS43, confirming epitope accessibility. These findings establish PfPIMMS43 as a promising target for malaria transmission-blocking interventions and propose an innovative strategy utilizing genetically modified mosquitoes expressing these nanobodies in conjunction with gene drive technology for enhanced malaria control and elimination efforts.Key Themes and Important Ideas:Malaria Transmission as a Target: The study emphasizes the importance of targeting the parasite's development within the mosquito vector to interrupt the human-to-mosquito and mosquito-to-human transmission cycle. This is presented as a crucial approach to complement existing malaria control measures, especially in the face of challenges like insecticide failure, climate change, and funding limitations. The transition from ookinete to oocyst in the mosquito midgut is identified as a "key developmental bottleneck" for the parasite.PfPIMMS43 as a Critical Transmission Target: The research highlights PfPIMMS43 as an "indispensable" surface protein for P. falciparum ookinetes and sporozoites. It is crucial for the ookinete-to-oocyst transition and plays a role in the parasite's ability to "evade the mosquito immune responses," specifically the complement-like system in the hemolymph. Previous studies, including those by the authors, had already indicated the potential of polyclonal antibodies targeting this protein in reducing transmission.Nanobodies as a Promising Intervention Tool: The study focuses on the development and application of VHH domain nanobodies as an alternative and potentially superior approach to conventional antibodies for transmission blocking. Nanobodies, derived from camelids and sharks, are described as "smaller, more easily produced monoclonal, heavy-chain variable (VHH) domain antibodies." Their advantages include:"small size (~15 kDa)""structural simplicity""strong binding affinity"Easily bioengineered for targeting parasite antigens in mosquito vectors.Development and Characterization of PfPIMMS43 Nanobodies: High-affinity nanobodies targeting PfPIMMS43 were successfully generated by immunizing llamas with recombinant PfPIMMS43. Nine nanobodies were selected based on variations in their antigen-binding regions (CDR1-3). Four nanobodies (G9, E5, C12, and E2) exhibited high nanomolar binding affinities to recombinant PfPIMMS43 (3, 5, 6, and 8 nM, respectively). These four nanobodies were also able to detect endogenous PfPIMMS43 protein expressed by P. falciparum ookinetes in infected mosquito midguts.Significant Transmission Blocking Activity (TRA): The developed nanobodies demonstrated significant transmission-reducing activity in mosquito feeding assays.In standard membrane feeding assays (SMFAs) using laboratory P. falciparum NF54 and An. coluzzii mosquitoes, the four high-affinity nanobodies (G9, E5, C12, and E2) significantly reduced oocyst numbers at a concentration of 100 µg/ml, with reductions ranging from 83% to 99%. Oocyst reduction was concentration-dependent.In direct membrane feeding assays (DMFAs) using natural P. falciparum isolates from gametocytaemic children in Tanzania and local An. gambiae mosquitoes, G9 and E5 (the two nanobodies with the highest affinities to recombinant PfPIMMS43) also showed significant TRA, with reductions of 99% and 79% at 100 µg/ml, respectively. Both nanobodies significantly reduced mosquito infection prevalence in field conditions.Epitope Mapping and Structural Insights: Epitope mapping revealed that the four nanobodies bind to "conserved regions in the second half of PfPIMMS43," specifically beyond amino acid residue 258. This suggests the C-terminal half of the protein is more immunogenic. G9 and E5 appear to recognize similar conformational ...
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  • Nanofiber Encapsulation of Pseudomonas for Sustained Mosquito Larvicide Release (April 2025)

    Nanofiber Encapsulation of Pseudomonas for Sustained Mosquito Larvicide Release (April 2025)
    Apr 21 2025
    Briefing Document: Nanofiber Encapsulation of Pseudomonas aeruginosa for Sustained Mosquito Larvicide ReleaseDate: Received - 13 December 2024 | Accepted - 04 April 2025 | Published - 21 April 2025 Source: Excerpts from "Nanofiber encapsulation of Pseudomonas aeruginosa for the sustained release of mosquito larvicides" https://doi.org/10.1038/s41598-025-97400-w1. Executive Summary:This study investigates a novel approach for mosquito vector control using nanofiber encapsulation of the bacterium Pseudomonas aeruginosa. The research addresses the inadequacy of current vector control strategies in eliminating mosquito-borne diseases by developing a method for the sustained release of bacterial larvicides. P. aeruginosa was selected for its potent larvicide production compared to other tested Pseudomonas species. The study demonstrates that encapsulating P. aeruginosa in electrospun nanofibers protects the bacteria, mimicking natural biofilms, enhances their survival in aquatic environments, and allows for prolonged larvicide production without harming non-target organisms (guppy fish). This nanotechnology-based method shows promise for controlling mosquito larvae in various breeding habitats over extended periods, potentially reducing application frequency and costs.2. Background and Problem Statement:Mosquito-borne diseases (malaria, dengue, chikungunya, Zika, etc.) pose a significant global health threat, affecting hundreds of millions annually.Existing vector control strategies, primarily chemical insecticides and environmental management, are often insufficient for complete vector elimination.Increased insecticide resistance and environmental concerns associated with chemical methods necessitate the development of novel, sustainable approaches.Biological control using bacteria like Bacillus thuringiensis var. israelensis and Bacillus sphaericus offers a safer alternative, but their efficacy depends on persistence in the environment.Sustained-release formulations of microbial larvicides are highly desirable to reduce application frequency and costs.Conventional immobilization techniques for sustained release often suffer from limitations like low diffusion and reduced microbial viability."Despite the rising global incidence of vector-borne diseases such as malaria, dengue, chikungunya, and Zika, existing vector control strategies remain inadequate for completely eliminating vectors from their breeding sites."3. Key Findings and Concepts:Superiority of Pseudomonas aeruginosa: Among the tested Pseudomonas species (P. fluorescens and P. putida), P. aeruginosa demonstrated the most potent larvicidal activity against four major mosquito vectors: Aedes aegypti, Culex quinquefasciatus, Cx. tritaeniorhynchus, and Anopheles stephensi."During the initial screening, Pseudomonas aeruginosa proved to be more effective than the other two tested species, P. fluorescens and P. putida, in producing potent larvicides and was therefore selected for nanofiber encapsulation studies."Nanofiber Encapsulation Technique: Electrospinning was used to create a thin fibrous material at the nanoscale (1 nm - 1 µm) from Pluronic F127 dimethacrylate (F127-DM) and polyethylene oxide (PEO) to encapsulate and immobilize live P. aeruginosa bacteria."In the present study, we rectified the shortcomings of conventional immobilization by developing a thin fibrous material at the nanoscale level (typically between 1 nm and 1 µm) using electrospinning to encapsulate and immobilize live bacteria."Protection and Sustained Release: Nanofiber encapsulation shields the bacterial cells from environmental stress, mimicking natural biofilms, thereby enhancing their survival and prolonging larvicide production. The cross-linking of the nanofibers prevents their rapid dissolution in water."This study aimed to encapsulate larvicide-producing bacteria in nanofibers designed to shield bacterial cells from environmental stress—mimicking natural biofilms—thereby enhancing their survival in aquatic habitats and prolonging larvicide production."Efficacy in Batch Systems (Container Breeding Habitats): Nanofiber-encapsulated P. aeruginosa demonstrated sustained larvicidal activity in batch systems (simulating stagnant water bodies). The spent water containing released metabolites remained lethal to all four tested mosquito species for at least 8 days."In the batch system, the spent water with metabolites of P. aeruginosa was lethal to all the tested species of larvae, such as Ae. aegypti, An. stephensi, Cx. tritaeniorhynchus, and Cx. quinquefasciatus, to varying degrees... The larvicidal potency of the spent water either remained the same as observed on the first day or increased during the subsequent days of incubation."Reduced Efficacy in Continuous Systems (Flowing Water Habitats): In continuous flow systems (simulating paddy fields or tanks with water inflow), the larvicidal efficacy of the released metabolites declined over subsequent days, suggesting...
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  • Predicting Aedes Albopictus Spread in Europe via Climate and Population (April 2025)

    Predicting Aedes Albopictus Spread in Europe via Climate and Population (April 2025)
    Apr 11 2025
    Population Dependent Diffusion Model for Aedes Albopictus Spread in EuropeSource: Barman et al., "A climate and population dependent diffusion model forecasts the spread of Aedes Albopictus mosquitoes in Europe," Nature Portfolio journal, 2025, https://doi.org/10.1038/s43247-025-02199-zDate: Received - 25 November 2024 | Accepted - 07 March 2025 | Published - 09 April 2025Key Themes and Important Ideas/Facts:This paper presents a novel spatio-temporal diffusion model that accurately forecasts the spread of Aedes albopictus mosquitoes in Europe by simultaneously considering climate suitability and human population factors. Ae. albopictus is a crucial vector for several arboviruses, including Dengue, Chikungunya, Zika, and Yellow Fever. The study highlights the increasing risk of autochthonous (local) transmission of these diseases in Europe due to the mosquito's expanding range, driven by environmental changes and global interconnectedness.1. Predictable Spread of Ae. albopictus:The core finding is that the expansion of Ae. albopictus in Europe is predictable by integrating climate suitability and human population predictors within a single spatio-temporal diffusion model.The model demonstrates high accuracy in predicting areas of presence and absence (99% and 79% respectively).This predictability allows for anticipating future outbreaks by understanding the interplay between vector suitability and introduction.Quote: "These results show that the expansion of Ae. albopictus in Europe is predictable and provide a basis for anticipating future outbreaks in situations of dependent interacting co-drivers."2. Drivers of Ae. albopictus Expansion:The study confirms that climate change (suitable climatic conditions), urbanization, and human population mobility are key factors facilitating the invasion of new habitats by this species.Quote: "Suitable climatic conditions favoured by climate change, urbanisation, and human populationmobility, seems to have facilitated the expansion of this invasive mosquito species into novel habitats."The passive transport of eggs through global travel and trade (e.g., used tires, lucky bamboo) and ground vehicles contributes significantly to its spread along transportation corridors.The mosquito's ecological and physiological plasticity (e.g., adaptation to cold, desiccation-resistant eggs, domestic container-breeding) enables its rapid and widespread expansion.3. Model Development and Performance:The researchers developed a "highly predictive spatio-temporal vector diffusion model" that integrates climate suitability (temperature, humidity) and human population data.The model is a generalized additive mixed (GAM) model fitted within a Bayesian framework (INLA).It accounts for both short-range spread (geographical proximity) and potential long-range spread influenced by human population.The model demonstrates good overall performance, with AUC values around 0.80 for predicting new establishments in previously uncolonized areas.Quote: "Notably, model evaluation reveals that new introduction of Ae. albopictus into naïve areas, are very well predicted, which has not been achieved before with this type of model."Two versions of the model were calibrated: one using raw climate and population covariates, and another using a mechanistic mosquito life cycle model output as a covariate. Both showed similar predictive performance.4. Key Covariates and Their Influence:Temperature: Median temperature (up to 24°C) shows a strong positive correlation with Ae. albopictus presence, decreasing at higher temperatures. Minimum temperature is positively correlated when median temperatures are high.Relative Humidity: Low relative humidity is negatively correlated with Ae. albopictus presence.Proximity: Geographical proximity to already established areas has a substantial impact on the spread, modeled through a spatio-temporal diffusion process.Human Population: Higher population density is associated with a higher likelihood of Ae. albopictus presence, likely reflecting increased introduction opportunities via human mobility, although the measured effect size was relatively small compared to climate factors.Human mobility modeled explicitly using a radiation model did not significantly improve model fit, suggesting that local diffusion and the human population covariate together can effectively capture its impact.5. Implications for Public Health:The model can be a valuable tool for preparedness and response to Aedes-borne infections by identifying high-risk areas for new introductions.Quote: "This model can be integrated into early warning systems and help delineate areas at risk for the introduction and establishment of Ae. albo-pictus."Predictions can help target awareness and prevention messages to susceptible populations and guide vector control efforts.The model can also inform healthcare system preparedness for potential epidemics and the strategic deployment of available arboviral vaccines...
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  • Malaria Transmission: Parasite and Vector Circadian Clock Coordination (April 2025)

    Malaria Transmission: Parasite and Vector Circadian Clock Coordination (April 2025)
    Apr 4 2025
    Parasite and Vector Circadian Clocks Mediate Efficient Malaria TransmissionSource: Bento et al., "Parasite and vector circadian clocks mediate efficient malaria transmission," Nature Microbiology, Published online 31 March 2025, https://doi.org/10.1038/s41564-025-01949-1Date: Received: 03 September 2024 | Accepted: 26 March 2025 | Published: 04 April 2025Key Themes:This study uncovers a critical tripartite relationship between the Anopheles mosquito vector, the Plasmodium malaria parasite, and the mammalian host, highlighting the significant role of their respective circadian clocks in mediating efficient malaria transmission. The research demonstrates that both the mosquito salivary glands and the resident sporozoite parasite exhibit substantial circadian transcriptional activity, preparing them for the nocturnal blood-feeding behavior of the mosquito and subsequent host infection. The alignment of these circadian rhythms, particularly during nighttime, is shown to be crucial for maximizing transmission efficiency.Most Important Ideas and Facts:Circadian Rhythms in Mosquito Salivary Glands:Approximately half of the Anopheles stephensi mosquito salivary gland transcriptome displays circadian expression.Genes essential for efficient bloodmeals, such as those encoding anti-blood clotting factors (e.g., anophelin/cEF, aegyptin), vasodilators (Peroxidase 5B), and anti-inflammatory proteins (D7 long form L2), exhibit rhythmic expression, peaking around the times when mosquitoes prefer to feed.The study found that mosquitoes prefer to feed and ingest more blood at nighttime, as demonstrated by higher hemoglobin levels in their midguts after nocturnal feeding ("measuring haemoglobin levels, we demonstrate that mosquitos prefer to feed and ingest more blood at nighttime").Circadian clock genes (Clock, Cycle, Period, Vrille) are also rhythmically expressed in the salivary glands, suggesting an internal clock regulating these transcriptional changes.This rhythmic expression in salivary glands occurs independently of light/dark cycles (LD vs. constant dark DD), indicating genuine circadian control ("Genes in the salivary glands of infected mosquitos cycled independently of the mosquito light/dark schedule (LD versus DD), suggesting that they are under circadian control and that the time of day (rather than light) is the main driver of transcriptional fluctuations in mosquito salivary glands").Proteomics analysis confirmed rhythmic abundance of some salivary gland proteins, including those involved in glycolysis.Circadian Rhythms in Salivary-Gland Sporozoites:A substantial subset (12-20%) of the Plasmodium berghei sporozoite transcriptome within the mosquito salivary glands also exhibits circadian cycling.This finding challenges the traditional view of salivary-gland sporozoites as transcriptionally quiescent ("Notably, we show a substantial subset of the salivary-gland-resident parasite transcriptome cycling throughout the day, indicating that this stage is not transcriptionally quiescent.").Sporozoite genes involved in motility, such as myosin A and thrombospondin-related sporozoite protein (TRSP), show rhythmic expression, potentially modulating their ability to initiate infection at different times of day ("Among the sporozoite genes undergoing rhythmic expression are those involved in parasite motility, potentially modulating the ability to initiate infection at different times of day.").Other cycling sporozoite genes include apical membrane antigen 1 (AMA1), circumsporozoite protein (CSP), and plasmepsin X, all implicated in invasion and host interaction.The rhythmic gene expression in sporozoites is not due to cell division within the salivary glands, as confirmed by EdU incorporation assays ("Taken together, our results show that the transcriptional daily rhythms identified in sporozoites are not a consequence of cell divi-sion but instead resemble a robust circadian rhythm.").Alignment of Rhythms for Efficient Transmission:The study proposes a "circadian tripartite relationship" between the vector, parasite, and mammalian host that modulates malaria transmission efficiency.Increased mosquito biting and blood ingestion occur at nighttime, aligning with the peak expression of bloodmeal-related genes in the salivary glands.Sporozoite motility-associated genes peak in the early morning, potentially preparing them for transmission during the mosquito's nighttime feeding.Experimental infections in mice demonstrated that parasite load in the liver was significantly higher when infection was initiated during the nighttime (using both nighttime sporozoites and mice) compared to daytime infections. This effect was abolished when the rhythms of sporozoites and mice were mismatched ("We observed a reduced parasite load in the livers of mice when infection was initiated during the daytime (using daytime sporozoites and mice) compared with nighttime infections (using nighttime sporozoites and mice; Fig. 4f). By ...
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  • Radiation Induces Alternative Splicing in Aedes aegypti (March 2025)

    Radiation Induces Alternative Splicing in Aedes aegypti (March 2025)
    Mar 24 2025
    Briefing Document: Radiation-Induced Alternative Splicing in Aedes aegypti MosquitoesSource: Bendzus-Mendoza, H., Rodriguez, A., Debnath, T., Bailey, C. D., Luker, H. A., & Hansen, I. A. (2025). Radiation exposure induces genome-wide alternative splicing events in Aedes aegypti mosquitoes. Scientific Reports, 15, 5885.Date of Publication: Received - 19 June 2024 | Accepted - 14 March 2025 | Published - 24 March 2025Key Themes and Important Ideas/Facts:This study investigates the impact of ionizing radiation on alternative splicing events (ASEs) in male Aedes aegypti mosquitoes, a crucial aspect for improving the sterile insect technique (SIT). The researchers compared RNA sequencing data from male mosquitoes irradiated with a standard dose of 50 Grey (Gy) of X-rays to that of un-irradiated control mosquitoes. Their findings reveal that radiation exposure induces significant changes in alternative splicing patterns across the mosquito genome, affecting genes involved in key biological processes.1. Background and Motivation:Aedes aegypti is a major vector for several deadly diseases, posing a significant public health threat. Controlling their populations is crucial."Aedes aegypti, the yellow fever mosquito, is the primary vector of several deadly diseases, including yellow fever, dengue fever, chikungunya, and Zika[1]. These insects are a major public health threat in many parts of the world, especially in tropical and subtropical regions[2,3]."SIT, which involves releasing sterile males to mate with wild females, is an environmentally friendly method for controlling pest populations."An alternative method for controlling Ae. aegypti populations is the sterile insect technique (SIT).""SIT has been proven safe, effective, and environmentally friendly since it does not involve the use of pesticides. It is species-specific and does not make use of genetically modified organisms[10]."Ionizing radiation is the preferred method for sterilizing male insects in SIT programs, typically using doses between 5 and 300 Gy depending on the species. The optimal dose for Ae. aegypti is 50 Gy."The use of ionizing radiation to sterilize male insects is the method of choice in many SIT programs[11].""The optimal radiation dosage for sterilizing male Ae. aegypti has been previously determined to be 50 Gy[16]."A significant challenge with SIT is that while 50 Gy sterilizes males, it also reduces their fitness and lifespan, hindering their ability to compete with wild males."While irradiating mosquitoes with 50 Gy causes complete sterility, it still reduces male fitness and lifespan[17]. This is a problem because sterile males must successfully compete with wild males for SIT to be effective."Previous research by the same group identified significant changes in gene expression (upregulation of DNA repair genes) in irradiated Ae. aegypti. This study focuses on the impact of radiation on alternative splicing."To better understand the impact of radiation exposure on mosquitoes, we previously investigated changes in the transcriptome of irradiated male Ae. aegypti. We found dramatic changes in the transcriptome, specifically a robust up-regulation of the transcription of DNA repair genes..."2. Key Findings on Alternative Splicing Events (ASEs):Radiation exposure significantly induced alternative splicing events in male Ae. aegypti."The results of our analysis of our dataset confirmed our hypothesis that radiation-exposure triggers specific and significant ASEs in mosquitoes."The study identified 289 significantly differentially alternatively spliced events (FDR < 0.05 and |Δ PSI| > 0.1) in 181 unique genes after irradiation."In total, we detected 15,016 ASEs among the transcriptomes of irradiated and non-irradiated mosquitoes... 289 of these ASEs were significantly differentially alternatively spliced between both groups... with 181 unique genes undergoing ASEs..."Five main types of ASEs were observed: alternative 3’ splice site (A3SS), alternative 5’ splice site (A5SS), mutually exclusive exon (MXE), retained intron (RI), and skipped exon (SE)."Specifically, 88 events were classified as alternative 3’ splice site events (A3SS), 104 as alternative 5’ splice site events (A5SS), 17 as mutually exclusive exon events (MXE), 12 as retained intron (RI) events, and 68 as skipped exon events (SE)..."A3SS, A5SS, and SE were the most prevalent types of ASEs induced by radiation. RI was the least common."Of these five, A3SS, A5SS, and SE are by far the most prevalent after irradiation treatment... In support of this notion, we found that RI is indeed the rarest type of ASE in our Ae. aegypti dataset."These radiation-induced ASEs occurred genome-wide, affecting genes on all three chromosomes of Ae. aegypti."The genes that undergo significant ASEs after irradiation were mapped to the three chromosomes of Ae. aegypti... We found that all five ASEs occurred genome wide."3. Functional Analysis of Alternatively Spliced Genes (ASGs):...
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  • Mosquito Prefoldin Targeting Blocks Plasmodium Transmission (March 2025)

    Mosquito Prefoldin Targeting Blocks Plasmodium Transmission (March 2025)
    Mar 7 2025
    Briefing Document: Targeting the Mosquito Prefoldin–Chaperonin Complex to Block Plasmodium TransmissionCitation: Dong, Y., Kang, S., Sandiford, S.L. et al. Targeting the mosquito prefoldin–chaperonin complex blocks Plasmodium transmission. Nat Microbiol (2025). https://doi.org/10.1038/s41564-025-01947-3Date: Received - 22 November 2024 | Accepted - 27 January 2025 | Published - 06 March 2025Overview:This study investigates the role of the conserved Anopheles mosquito prefoldin (PFDN)–chaperonin (CCT/TRiC) system as a potential target for blocking the transmission of multiple Plasmodium species. The researchers demonstrate that disrupting this protein folding complex in mosquitoes, either through gene silencing or antibody inhibition, significantly reduces Plasmodium infection intensity and prevalence. The mechanism of action involves compromising the integrity of the mosquito midgut, leading to immune activation and the disruption of the parasite's immune evasion strategies. The findings suggest that the PFDN–chaperonin complex, particularly the PFDN6 subunit, holds promise as a multispecies transmission-blocking vaccine (TBV) target.Main Themes and Important Ideas/Facts:The Mosquito PFDN–Chaperonin Complex is Essential for Plasmodium Infection:The Plasmodium infection cycle in mosquitoes relies on various host factors in the midgut.The mosquito prefoldin complex is crucial for the proper folding of proteins and macromolecular complexes, including actin and tubulin, which are essential for cell division, motility, cytoskeletal stability, and signal transduction – all of which influence Plasmodium infection.Silencing any of the six PFDN subunits (Pfdn1-6) or the CCT4 subunit via RNA interference significantly reduced Plasmodium falciparum oocyst loads in the Anopheles gambiae midgut."Silencing any prefoldin subunit or its CCT/TRiC partner via RNA interference reduces Plasmodium falciparum oocyst loads in the mosquito midgut..."Co-silencing of different PFDN subunits did not have an additive effect, confirming that the complex functions as a unit in supporting parasite development.Targeting PFDN6 with Antibodies Blocks Plasmodium Transmission:Co-feeding mosquitoes with a PFDN6-specific antibody along with P. falciparum gametocytes resulted in a potent suppression of parasite infection at both the oocyst and sporozoite stages."Ingestion of purified anti-PFDN6 polyclonal antibody (IgG) resulted in a significant decrease in parasite loads (either at the oocyst or sporozoite stage) compared with control cohorts fed on rabbit anti-GFP antibody..."The level of inhibition achieved with anti-PFDN6 antibodies was comparable to that of leading TBV candidates like Pfs230 and Pfs25, as well as antibodies targeting mosquito proteins AgAPN1 and FREP1.Anti-PFDN6 antibody also effectively blocked P. falciparum transmission in Anopheles stephensi and Plasmodium vivax transmission in Anopheles dirus, indicating a broad-spectrum effect across different mosquito and parasite species.Active immunization of mice with recombinant PFDN6 protein resulted in antibodies that, when mosquitoes fed on the immunized, infected mice, significantly reduced Plasmodium berghei oocyst infection intensity and prevalence, supporting its potential as a TBV target.PFDN Supports Plasmodium Development After Ookinetes Invade the Midgut Epithelium:Antibody blocking assays showed no significant difference in ookinete numbers in the midgut lumen at 24 hours post-infection, but a significant decrease in oocyst loads was observed at 36 hours and 8 days.Injection of anti-PFDN6 antibody into the mosquito haemolymph also reduced oocyst numbers, suggesting an effect on the basal side of the midgut epithelium where oocysts develop."These results indicate that PFDN6 host factor function is exerted upon ookinete egress and oocyst formation on the basal side of the epithelium beneath the basal lamina."PFDN6 distribution largely overlapped with actin in the midgut epithelium, but it did not co-localize directly with the parasites, suggesting an indirect role in parasite development.Disruption of PFDN Compromises Midgut Integrity and Triggers Anti-Plasmodium Immunity:Attempting to create a Pfdn6 knockout mosquito line resulted in pre-adult lethality, likely due to cytoskeletal and gut integrity issues.Co-immunoprecipitation assays identified interactions between PFDN6 and actin, tubulin, and several extracellular matrix proteins, supporting its role in maintaining cellular and matrix integrity.Silencing Pfdn6 or co-feeding with anti-PFDN6 antibodies led to a "leaky gut," characterized by increased permeability and bacterial leakage from the midgut lumen into the haemolymph."Interfering with the PFDN–CCT/TriC chaperonin complex results in a cascade of events, including compromised gut integrity and disrupted extracellular matrix organization. The increased gut permeability leads to bacterial leakage and systemic infection, ultimately augmenting ...
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