Biology subjects

Tomazatos, A.

Publications and source records attributed to Tomazatos, A..

3 recordsLinked to original sources

bioRxiv2025

Morphological and genetic heterogeneity in Aedes aegypti (Diptera: Culicidae) populations across diverse landscapes in West Africa

Native to sub-Saharan Africa, Aedes aegypti has spread across the globe and is now one of the most significant vectors of arboviruses worldwide. However, data on the ranges of its populations remain sparse, and the genetic variability and ecological adaptability in West Africa are still poorly understood. In this study, we characterized the morphological and genetic diversity of Ae. aegypti across four landscape types (urban, peri-urban, rural, and sylvatic sites) in three West African countries (Burkina Faso, Cote dIvoire, and Ghana). Ae. aegypti exhibited significant variation in abdominal scaling patterns across countries and landscape types, with the sylvatic and urban populations in Burkina Faso displaying the highest proportions of white scales (>50% white scales), while black scales predominated among those from Cote dIvoire and Ghana (>80% black scales). Wing shape displayed limited differentiation between the countries, landscape types, and genetic clusters. Bayesian analysis indicated high gene flow among populations, with notable outliers observed in sylvatic sites from Burkina Faso and admixture patterns suggesting possible human-mediated dispersal. Additionally, two major mitochondrial lineages, clades A and B, were identified. Most samples were categorized under clade B, showing no evidence of clustering by country or landscape type. In contrast, clade A comprised primarily sylvatic specimens from Burkina Faso and a single urban individual from Cote dIvoire. These findings highlight the complex interplay of genetic, environmental, and ecological factors shaping the variations in Ae. aegypti populations in West Africa. They provide insights into the phenotypic and genetic diversity of Ae. aegypti, offering valuable implications for understanding arbovirus transmission dynamics and formulating targeted interventions against arboviral diseases.

ecology↗

bioRxiv2025

Ambecovirus, a novel Betacoronavirus subgenus circulating in neotropical bats sheds new light on bat-borne coronaviruses evolution

Understanding the viral diversity harboured by wildlife is essential for effective prediction and prevention of future zoonotic outbreaks. Bats, in particular, are recognized as natural reservoirs for several zoonotic viral pathogens of high impact on public health, including coronaviruses responsible for SARS, the rabies virus, Marburg, Ebola, Nipah and Hendra viruses. However, the large extent of bat viruses remains unexplored, especially in highly biodiverse regions of the Neotropics such as Brazil. We used a meta-transcriptomic to characterize new virus genomes found in blood, oral and anal samples collected from cave- and non-cave bats from Northeast Brazil. From a total of 19 coronavirus-positive bats, we have assembled two complete genomes of a new Betacoronavirus subgenus, named Ambecovirus (American betacoronavirus). The subgenus herein described is phylogenetically placed between the Sarbeco-/Hibeco-/Nebecovirus and the Merbeco-/Embecovirus clades, being basal to the former. While the conserved S2 region of the spike protein retained hallmark domains, including HR1 and HR2, the S1/S2 cleavage site and the furin cleavage site, the S1 region consistently displayed only the N-terminal domain. The receptor-binding domain could not be identified due to high dissimilarity relative to known congeneres. The detection of Ambercovirus in sympatric Pteronotus gymnonotus and Carollia perspicillata bats suggests interspecies transmission. Longitudinal sampling confirmed persistent Ambecovirus infection in P. gymnonotus over multiple years and virus dispersion at a minimum distance of 270 km between caves. The present study confirms that viral diversity in neotropical hosts remains largely unknown not just in Brazil but, likely, in the other countries of the region, supporting the need for a systematic approach to virome exploration and analysis followed by in vitro experimentation to assess zoonotic potential.

evolutionary biology↗

bioRxiv2022

The virome of bats inhabiting Brazilian biomes: knowledge gaps and biases towards zoonotic viruses

Bats are hosts of a large variety of viruses including some that may infect other vertebrates and humans. Research on bat-borne viruses attracted significant attention in recent years mainly due to epizootics caused by viruses having bats as hosts. The characterization of the viral communities of bats was then prioritized, but despite increasing efforts, there are large disparities in the geographical ranges covered and the methodologies employed around the world. As a result, large gaps remain in our current understanding of bat viromes and their role in disease emergence. This is particularly true for megadiverse regions in Latin America. This review aims to summarize the current understanding about bat-viruses that inhabit Brazilian biomes, one of the most bat species-rich and diverse regions of the globe. Taking into account all known bat-associated viral families studied in Brazilian biomes, we found that almost half of all bat species (86/181 species) were not investigated for viruses at all. Moreover, only a small fraction of viral lineages or families have been studied more in depth, usually employing targeted methods with limited power to characterize a broad virus diversity. Additionally, these studies relied on limited spatio-temporal sampling and small sample sizes. Therefore, our current understanding of bat viral communities in the Brazilian biomes is limited and biased at different levels, limiting zoonotic risk assessments of bat-borne viruses. Considering these limitations, we propose strategies to bridge the existing gaps in the near future.

microbiology↗