Biology subjects

Sousa, C. A.

Publications and source records attributed to Sousa, C. A..

8 recordsLinked to original sources

bioRxiv2026

Transcriptomic profiling reveals multiple mechanisms of insecticide resistance in Aedes aegypti from Angola

Control of arboviruses remains heavily reliant on insecticide-based vector control targeting adult Aedes aegypti, especially during outbreaks, but the effectiveness of these tools can be compromised by insecticide resistance. While the mechanisms underlying resistance have been widely studied in Latin American and South East Asian Ae. aegypti, knowledge from African populations is limited, particularly regarding metabolic resistance. To address this knowledge gap, we sequenced the transcriptomes of Ae. aegypti collected in Angola, from both unexposed individuals and survivors of exposure to the organophosphate fenitrothion, alongside two insecticide-susceptible laboratory reference strains. Many overexpressed genes belonged to the major detoxification enzyme families, including 96 cytochrome P450 monooxygenases (CYP450s), 18 glutathione S-transferases (GSTs), and 35 carboxylesterases, with multiple genes previously detected as upregulated in Latin American and Asian populations. These included frequently reported, functionally-validated, metabolic resistance genes such as CYP9J24, CYP9J26, and CYP6BB2. However, expression of auxiliary resistance families including hexamerins, heat shock proteins, and odorant binding proteins were linked to the insecticide resistance phenotype, whilst numerous cuticular genes differentiated the Angolan population from both susceptible laboratory strains. A novel candidate, CYP6AG7, that was overexpressed after fenitrothion exposure was experimentally validated, and surprisingly metabolised fenitrothion into its toxic oxon form, which it did not subsequently break down. The antioxidant response element (ARE) motif, to which the transcription factor Maf-S binds, was detected in all CYP450 overexpressed in the fenitrothion treatment suggesting their potential coordinated induction. Analysis of genetic differentiation revealed several resistance-linked genes under potential selection, and SNP screening identified both known and novel non-synonymous mutations in the voltage-gated sodium channel (VGSC) gene, the target for pyrethroid insecticides. This is the first RNAseq dataset for Ae. aegypti from Africa in the context of insecticide resistance, providing insight into the complexity of resistance mechanisms, including some shared, and others potentially novel, compared to better studied populations from other geographical regions. Author summaryDengue, chikungunya, yellow fever, and Zika are diseases that exert an increasing public health burden across Africa, primarily transmitted by the mosquito Aedes aegypti. We rely heavily on insecticides to control these mosquitoes, but populations are increasingly developing resistance, making control efforts less effective. While resistance mechanisms have been well-studied in the Americas and Asia, comparatively little is known about how African Ae. aegypti resist insecticides. We collected Ae. aegypti mosquitoes from Angola and compared the genes expressed in fenitrothion resistant versus susceptible mosquitoes using RNA sequencing. We identified overexpressed candidate insecticide resistance genes from the detoxification enzyme families that mosquitoes use to break down insecticides, including several genes previously linked to resistance in other regions. One novel enzyme identified, CYP6AG7, was experimentally validated and found to convert the pro-insecticide fenitrothion into its harmful form but interestingly not break down this harmful metabolite further. Mutations potentially linked to insecticide resistance were also detected in detoxification genes and insecticide target site genes. Our study provides the first comprehensive molecular characterization of insecticide resistance mechanisms in African Aedes aegypti, offering crucial data to inform vector control strategies and insecticide resistance management across the continent as dengue and related diseases continue to spread.

bioinformatics↗

bioRxiv2026

Trait based assessment of the invasion potential of disease vector mosquitoes

Mosquito-borne diseases pose a growing global health threat, largely driven by the human-mediated spread of vector species beyond their native regions. Although only a few mosquito species historically established populations outside their native ranges, many have expanded rapidly in recent decades. Once established, these invaders are notoriously difficult to control, emphasizing the need for proactive identification before human-mediated spread occurs. Here, we present a framework to anticipate invasion potential for 184 mosquito species of medical importance based on their ecological, life-history, and macroecological traits. We first compiled a comprehensive dataset of 26 traits characterizing each species. We then used random forest models to relate these traits with the probability of species being introduced in new regions (before and after 1950, marking the onset of widespread trade globalization), and of establishment following introduction. Models achieved moderate to good predictive performance (AUC = 0.78-0.85) and revealed that species native to Asia and Australia, adapted to human-made breeding sites, and tolerant of climatic extremes are consistently more likely to be introduced and to establish in non-native regions. Among species with no known invasion history, we identified 24 with higher potential to become future spreaders, of which 17 also exhibit high establishment probabilities ( high-risk species). These results show that invasion potential can be inferred, to some extent, from intrinsic species traits and provide a quantitative basis for proactive surveillance, enabling prioritization of species most likely to become introduced in the future. Author SummaryMosquito-borne diseases threaten more than half of the worlds population and cause over 700,000 deaths each year. Only a small share of mosquito species can spread these diseases, but some of them are moving into new regions where they have never been seen before. The spread of these mosquitoes has led to increasing numbers of locally transmitted outbreaks in regions that previously, or in recent times, had no mosquito-borne diseases. Human activities like trade and travel help mosquitoes spread, and once they arrive, they are extremely difficult to eradicate. Therefore, it is crucial to understand which species may spread in the future and to identify those that should be closely monitored to prevent their introduction and establishment. In this work, we linked species characteristics with their known invasion history to identify the factors driving their introduction and establishment in new regions. We found that species from Asia and Australia, capable of using human-made breeding sites, and tolerant of climatic extremes are most likely to become invaders. We then used these findings to predict which species might spread next. We identified 24 species with high invasion potential, including 17 that also have high chances of establishing once introduced. These results demonstrate that invasion risk can be predicted from measurable species traits, providing a framework to guide early-warning surveillance and prioritize species for monitoring before they begin spreading and become widespread vectors of human disease.

ecology↗

bioRxiv2025

Developmental Dysregulation of Synaptic and Myelin-Related Genes in Frontal Cortex and Serum Infrared Spectroscopy Signature in the Valproic Acid Model of Autism

Neural circuits emerge during development through dynamic interactions between genetic instructions and environmental cues that shape cell fate, connectivity, and the timing of myelination. In developmental disorders such as autism, abnormalities in sensory processing, social cognition, and motor behavior are thought to arise from disruptions in these processes. Here, we investigated early-life molecular changes following prenatal exposure to valproic acid (VPA), an environmentally induced model of autism. We integrated cortical gene expression analysis using RNA sequencing/qPCR, alternative splicing profiling, in situ myelin quantification, plasma serotonin determination, and machine learning-assisted classification of blood serum molecular profiles using infrared spectroscopic (FTIR) data. Our findings revealed downregulation of myelin-associated genes and upregulation of synapse-related genes in the frontal cortex of young VPA-exposed rats. qPCR confirmed reduced cortical expression of Mobp and PLP1 along with increased Penk and C1ql3 expression. Alternative splicing analysis identified numerous novel transcript variants, enriched in synaptic-related genes, indicating widespread post-transcriptional remodeling in VPA animals. These molecular alterations were accompanied by a significant reduction in myelin content within the cingulate and motor cortex of adult animals. Peripheral molecular profiling showed elevated plasma serotonin in VPA-treated animals and demonstrated that a support vector machine trained on serum FTIR spectra classified VPA-exposed animals with 85% accuracy. Collectively, our findings suggest that prenatal VPA exposure induces early dysregulation of myelin organization, synaptic gene networks, and RNA splicing programs, potentially leading to long-term impairments in neuronal communication and processing efficiency. Furthermore, our results highlight serum spectroscopic signatures as promising peripheral biomarkers for autism, warranting further investigation.

neuroscience↗

bioRxiv2024

Global invasion patterns and dynamics of disease vector mosquitoes

Mosquitoes are regarded as the most dangerous creatures on earth, spreading deadly pathogens through their bites. Human activities are driving range expansions of many mosquito species by unintentionally introducing them beyond their native ranges. Despite the often dire consequences for human health, a global picture of the introduction trends and the resulting range expansions of mosquitoes is missing. Here, we describe the global invasion patterns of mosquitoes that are vectors of human diseases and analyze the drivers shaping them. In addition, we provide the dataset compiled for these analyses which represent the most up-to-date standardized information on first records for this taxonomic group at a regional level. Our findings reveal that a total of 45 mosquito species have hitherto been introduced into regions outside their native range worldwide, representing 24% of those known to transmit human pathogens in the wild (i.e., outside experimental conditions), with 27 species successfully established. There has been a steep increase in introductions of emerging non-native mosquito species since the mid-20th century when 28 species (62% of all introduced species) were recorded for the first time. In just the last two decades, 12 new species have been identified. The geography of introductions largely mirrors global trade and transportation flows. Initially, most introduced species were native to Africa, but over time, Asian species have become more dominant. North America, Australia and Europe have consistently been the primary recipients. Our results provide a foundation for addressing the increasing threat of non-native vector mosquitoes globally, emphasizing the need for international cooperation and comprehensive control measures to mitigate their impact on public health.

ecology↗

bioRxiv2024

Characterization of the microbiome of Aedes albopictus populations in different habitats from Spain and Sao Tome: implications for vector control.

The mosquito microbiome significantly influences vector competence, including in Aedes albopictus, a globally invasive ectoparasite. Describing the microbiome and Wolbachia strains of Ae. albopictus from different regions can guide area-specific control strategies. Mosquito samples from Spain and Sao Tome were analyzed using 16S rRNA gene sequencing and metagenomic sequencing. Wolbachia infection was genotyped, and statistical analysis compared infection patterns by sex and population. Results revealed a dominance of dual Wolbachia infections in the microbiome of both populations of Ae. albopictus, especially among females. The two populations presented a shared microbiome, although 5 and 9 other genera were only present in Spain and Sao Tome populations, respectively. Genera like Pelomonas and Nevskia were identified for the first time in Aedes mosquitoes. This study is the first to describe the Ae. albopictus bacteriome in Spain and Sao Tome, offering insights for the development of targeted mosquito control strategies.

molecular biology↗

bioRxiv2022

Screening of natural Wolbachia infection in mosquitoes (Diptera: Culicidae) from Cape Verde Islands

BackgroundWolbachia pipientis is an endosymbiont bacteria that induce cytoplasmic incompatibility and inhibit arboviral replication in mosquitoes. This study aimed at estimating the prevalence and genetic diversity of Wolbachia in different mosquito (Diptera: Culicidae) species from Cape Verde. MethodsMosquitoes were collected in six islands of Cape Verde using dippers/pipettes, BG-sentinel(R) traps, CDC light traps, and dorsal aspirators. Samples were identified to species using morphological keys and PCR-based molecular assays. Wolbachia was detected by amplifying a fragment of the surface protein gene (wsp). Multilocus sequence typing (MLST) was performed with five housekeeping genes (coxA, gatB, ftsZ, hcpA and fbpA) and the wsp hypervariable region (HVR) for strain identification. Identification of wPip groups (wPip-I to wPip-V) was performed using PCR-RFLP assay on the ankyrin-domain gene pk1. ResultsNine mosquito species were collected, including the major vectors Aedes aegypti, Anopheles arabiensis, Culex pipiens s.s. and Culex quinquefasciatus. Wolbachia was detected in Cx. pipiens s.s. (100% prevalence), Cx. quinquefasciatus (98.3%), Cx. pipiens/quinquefasciatus hybrids (100%) and Culex tigripes (100%). Results from MLST and wsp hypervariable region typing showed that Wolbachia from Cx. pipiens s.l. belong to Sequence Type 9, wPip clade and supergroup B Wolbachia. Phylogenetic analyses indicate that Wolbachia isolated from Cx. tigripes belongs to Supergroup B but integrates a distinct clade from wPip with no attributed MLST profile. PCR-RFLP revealed wPip-II, wPip-III and wPip-IV groups in Culex pipiens s.l. wPip-IV was the dominant group, while wPip-II and wPip-III were restricted to Maio and Fogo islands, respectively. ConclusionOur study showed a high prevalence and diversity of Wolbachia in Cx pipiens s.l. from Cape Verde islands and, to the best of our knowledge, is the first to detect Wolbachia in Cx. tigripes, being represented in this species by a previously undescribed MLST Sequence Type.

molecular biology↗

bioRxiv2022

Forecasting the numbers of disease vectors with deep learning

Arboviral diseases such as dengue, Zika, chikungunya or yellow fever are a worldwide concern. The abundance of vector species plays a key role in the emergence of outbreaks of these diseases, so forecasting these numbers is fundamental in preventive risk assessment. Here we describe and demonstrate a novel approach that uses state-of-the-art deep learning algorithms to forecast disease vector numbers. Unlike classical statistical and machine learning methods, deep learning models use time series data directly as predictors and identify the features that are most relevant from a predictive perspective. We demonstrate the application of this approach to predict temporal trends in the number of Aedes aegypti mosquito eggs across Madeira Island for the period 2013 to 2019. Specifically, we apply the deep learning models to predict whether, in the following week, the number of Ae. aegypti eggs will remain unchanged, or whether it will increase or decrease, considering different percentages of change. We obtained high predictive accuracy for all years considered (mean AUC = 0.92 {+/-} 0.05 sd). We also found that the preceding numbers of eggs is a highly informative predictor of future numbers. Linking our approach to disease transmission or importation models will contribute to operational, early warning systems of arboviral disease risk.

ecology↗

bioRxiv2018

What is known about modified insects for disease prevention?: a systematic review

The modification and release of insects to suppress or replace natural insect vectors constitutes a promising tool for vector control and disease prevention, facing the unprecedented global emergence of vector-borne diseases. Little is known regarding these innovative modification strategies and available evidence is not standardized turning it difficult to reflect on their actual efficacy and eventual effects.\n\nThis work conducted a systematic review, gathering and analyzing research articles from PubMed and Biblioteca Virtual em Saude databases whose results directly report efficacy and effects of the use of modified insects for disease prevention until 2016. Within more than 1500 publications that were screened a total of 349 where analyzed.\n\nA total of 12/3.4% reported field-based evidence, and 41/11.7% covered modification stretagies efficacy after insects release, their epidemiology impact or its long-term efficacy. Examples of successful results were the replacement of natural field populations by wolbachia-infected mosquitoes in 5 weeks, and the elimination of a population in laboratory cages after transgenic mosquitoes release over 10-20 weeks. Variability in the effective results were described (90/25.7%) questioning its reproducibility in different settings. We also found 38/10.9% publications reporting reversal outcomes, such as an increase of vector population after release. Ecological effects such as horizontal transfer events to non-target species (54/15.5%), and wolbachia-induced worsening pathogenesis on mammal filarial diseases (10/2.9%) were also reported.\n\nPresent work revealed promising outcomes of both suppressing and replacing approaches. However, it also revealed a need of field-based evidence mainly regarding epidemiologic and long-term impact of insect modification strategies. It pointed out some eventual irreversible and important effects that must not be ignored when considering open-field releases, and that may constitute constraints to generate the missing field evidence. Moreover, the level of variability of existing evidence suggests the need of local/specific evidence in each setting of an eventual release.\n\nAuthor summaryInnovative strategies are needed to arrest the unprecedented increase of vector-borne disease incidence, distribution and severity. Several modification techniques are being tried all over the world. However this is still an emergent topic with scarce available information and of complex understanding.\n\nPresent work is the unique structured review regarding the use of modified insects for vector-borne disease prevention, bringing neutral and robust evidence that will contribute with critical insights regarding these approaches.\n\nHere we explored more than 1200 publications and analyzed 349 publications on this subject, describing the actual efficacy and reported effects of several modification strategies. More than 30 categories were reported such as, the type of modification, the year of the publication, the species were results were tested, the type of study, and also type of Efficacy Outcome (from modification to long-term) and/or the type of Effects Outcome (from physiologic to ecologic effects). Analysis revealed promising outcomes regarding vector-control and disease prevention. However insects modification strategies still lack field-based evidence mainly regarding epidemiological and long-term efficacy. Eventual reversal outcomes on disease transmission, or irreversible biological effects (including horizontal transfer to non-target species or worsening pathogenesis in particular diseases in mammals), were also described. These effects need to be explored, dispelled or resolved before field trials occur in human residential areas. Some of these questions could only have a robust answer if these strategies would be implemented, needing to take the risk to observe reversal outcomes and/or irreversible effects. These findings reflect the big dilemma that is under the use of modified insects to prevent vector-borne diseases. Findings could support health authorities in decision-making and regulatory committees during advisory processes, by evaluating the pros/cons of each modifying technique for a particular setting. Moreover they could also summarize what is crucial to inform to communities if planning open field releases in residential areas.

ecology↗