Biology subjects

Alves, P. C.

Publications and source records attributed to Alves, P. C..

12 recordsLinked to original sources

bioRxiv2026

Post-outbreak surveillance reveals contrasting circulation dynamics of West Nile, Usutu and Bagaza viruses in southern Portugal, 2021 - 2023

Mosquito-borne orthoflaviviruses pose a significant threat to human and animal health worldwide. In Europe, West Nile (WNV), Usutu (USUV) and Bagaza (BAGV) viruses have expanded their geographic distribution and are detected with increasing frequency. Following the emergence of BAGV in 2021, we investigated the circulation dynamics and genomic diversity of orthoflaviviruses in southern Portugal, where their epidemiology remains poorly understood. Active Orthoflavivirus surveillance was conducted in birds and mosquitoes during 2021-2023 using serological and molecular assays, complemented by viral genome sequencing and phylogenomic analyses. Viral RNA was detected in 3.5% (41/1,171) of birds, while seroneutralization assays identified an overall seroprevalence of 55.3% (503/910). WNV RNA (lineage-1, strains WMed-1.2 and WMed-1.3) was detected annually in resident birds, including Alectoris rufa, Cyanopica cooki and Garrulus glandarius (1.5%, 18/1,171), and in Culex univittatus mosquitoes (0.8%, 2/255). Together with a WNV-specific seroprevalence of 28.5% (259/910) in birds, these findings support sustained local circulation. USUV RNA (Africa 3.1 sub-lineage) was detected in A. rufa in 2021 and 2023 (0.2%, 2/1,171), but seroprevalence was low (1.3%, 8/623), consistent with intermittent circulation. BAGV RNA (genotype-2) was detected only during the 2021 outbreak in A. rufa and Emberiza calandra (1.8%, 21/1,171), although BAGV-specific antibodies (6.6%, 60/910) were detected for up to two years after the outbreak, suggesting continued exposure or low-level circulation. Overall, our findings reveal contrasting circulation dynamics of orthoflaviviruses in southern Portugal. Sustained WNV circulation implies the need to strengthen avian and human surveillance in Portugal to better assess its public health risk, while the sporadic detection of USUV and BAGV underscores the value of long-term, integrated One Health surveillance for improving early warning and preparedness for emerging mosquito-borne diseases.

genetics↗

bioRxiv2026

Extensive nuclear introgression accompanied ancient mitochondrial capture in the common ancestor of two sister hare species

Pleistocene climatic oscillations promoted contact and hybridization among hare species, leaving lasting genomic signatures. Two sister species, L. castroviejoi (broom hare, endemic to Iberia) and L. corsicanus (Italian hare, endemic to Italy), carry fixed mitogenomes from L. timidus (mountain hare), an Arctic species widespread in southern Europe before deglaciation. Whether such turnover was accompanied by nuclear introgression, and how it affects their genomes today, remains unclear. Here, we date the ancient mitochondrial replacement in the broom-Italian hare ancestor using whole mitogenomes incorporating Iron Age samples. Coalescent modelling of complete genomes infers a substantial mountain hare contribution (24%) to this ancestor ~900 Kya (~5N generations). Accordingly, phylogenetic segmentation identified genomic segments consistent with mountain-to-broom/Italian hare introgression, covering ~17.8% of the autosomes, close to ~18% expected under drift, given admixture's timing and magnitude. Genome polarisation corroborates this estimate, with 25-28% of the mountain hare genome polarising with broom and Italian hares rather than its sister Iberian hare, decreasing to 15-18% at diagnostic sites. The introgression segments concentrate fixed-introgression sites and show sharp transitions of ancestry at their borders. Highly introgressed regions are gene-dense, and regions of reduced introgression are repeat-rich, suggesting that recombination shapes the introgression landscape. They also harbour genes with mitochondrial function that mirror candidates linked to mito-nuclear coadaptation in the Iberian hare, hinting that mitonuclear interactions may influence which variants persist. Our study illustrates how combining demographic, phylogenomic and polarisation-based methods can quantify and localize extensive nuclear introgression, even in the absence of non-introgressed reference populations.

evolutionary biology↗

bioRxiv2026

Isolation and characterization of Bagaza virus: insights into host adaptability and zoonotic potential.

Bagaza virus (BAGV) is an emerging orthoflavivirus that primarily infects wild birds, but its ability to infect other hosts remains poorly understood. We isolated BAGV RNA from the brain of a dead red-legged partridge and evaluated viral adaptation and replication kinetics in avian, mosquito, mammalian, and human cell lines. BAGV replicated efficiently in monkey, mosquito, duck, and selected human cell lines (HEK-293T and Huh7.5), whereas replication was limited in other human, hamster, and chicken fibroblast cell lines, indicating variable cellular susceptibility. These differences may reflect host-specific adaptation or distinct innate immune responses. Viral RNA replication complexes localized to the cytoplasm, as shown by immunocytochemical detection of dsRNA. Ribavirin treatment significantly reduced viral titers and RNA levels, demonstrating antiviral sensitivity. Together, these findings provide new insights into BAGV biology, host adaptability, and potential zoonotic risk, and support the development of antiviral strategies and improved epidemiological surveillance within a One Health framework.

microbiology↗

bioRxiv2024

Usutu virus African 3.1 lineage, Portugal, 2021-2023

BackgroundUsutu virus (Orthoflavivirus usutuense, USUV), a neurotropic arthropod-borne RNA virus of the family Flaviviridae, is a zoonotic virus that has spread throughout the European continent over the last three decades, since its emergence in Italy in 1996. However, no cases of USUV have been reported in Portugal so far. Material and methodsIn the scope of an active surveillance program for Orthoflavivirus, we collected growing feather samples from 249 red-legged partridges (Alectoris rufa) hunted in southern Portugal during the 2021-2023 hunting seasons. Samples positive for USUV were subjected to whole genome sequencing and strain characterization. ResultsTwo partridges tested positive for USUV. Phylogenetic analyses of whole and partial genomes assigned the USUV strains to the African 3 lineage, specifically the African 3.1 sub-lineage. ConclusionsOur study confirms, for the first time, the circulation of USUV in wild birds in Portugal. Active surveillance of hunted partridges proved to be a useful, accessible, and cost-effective method for USUV monitoring, further supporting their value as effective sentinels for Orthoflavivirus surveillance. Given the ongoing circulation of USUV and the increasing risk of its spillover to other domestic and wild animals, and humans, additional efforts are needed to improve virus surveillance in Portugal from a One Health perspective.

microbiology↗

bioRxiv2024

Using integrated wildlife monitoring for quantifying the impact of emerging Bagaza virus in red-legged partridges in Portugal, 2012-2024

Bagaza virus, a vector-borne flavivirus that causes significant mortality in wild bird species, emerged in Portugal in September 2021. This study used integrated wildlife monitoring to quantify its impact on a natural population of red-legged partridge (Alectoris rufa) in southern Portugal. We constructed a baseline model of population dynamics prior to the outbreak (2012-2021) and used this model to predict population size in subsequent years (2022-2024). This model, which included population abundance and demographic data of red-legged partridge, as well as climatic variables, showed a strong fit to the observed data, and the difference between the predicted and observed population size in 2022 suggests a Bagaza-induced mortality rate of at least 59% (95% CI 52-66%). In addition to enabling the adaptive management of populations, our results demonstrate that integrated wildlife monitoring offers epidemiological insights for risk assessment, highlighting its role in proactive wildlife disease surveillance within the One Health framework.

ecology↗

bioRxiv2024

Dynamics of Bagaza, West Nile, and Usutu viruses in Portugal revealed by long-term serological surveillance in red-legged partridges, 2018-2022

BackgroundBagaza virus (BAGV) emerged in Portugal in 2021. BAGV and other flaviviruses such as West Nile virus (WNV) and Usutu virus (USUV) represent emerging threats in Europe, yet uncertainties persist regarding their epidemiological status in Portugal. AimThis study aimed to elucidate the epidemiological dynamics of BAGV, WNV, and USUV in Portugal using the red-legged partridge (Alectoris rufa) as a susceptible bird model species. MethodsSerum samples collected from a partridge population in Southern Portugal, between 2018 and 2022, were analysed to characterize exposure to flaviviruses through enzyme-linked immunosorbent assay (ELISA; n=468) and virus neutralization test (VNT; n=433). ResultsELISA test revealed an average seroprevalence of 58.1% for WNV and WNV-cross-reacting antibodies between 2018 and 2022, while 66.3% of individuals tested positive using VNT: 28.8% specific for WNV, 8.1% for BAGV, 2.1% for USUV and 27.2% for "undetermined flaviviruses". BAGV seroprevalence was first detected in October 2021 (8.7%), alongside an outbreak detection, peaking in November 2021 (26.3%) and persisting until October 2022 (2.3%). WNV antibodies were detected throughout all sampling periods, with the highest seroprevalence in October 2020 (44.8%). USUV seroprevalence was detected until the BAGV outbreak in 2021, peaking in October 2020 (6.9%). ConclusionLong-term serological surveillance of partridges revealed endemic circulation of WNV and sporadic circulation of BAGV and USUV in Portugal. Notably, the highest WNV seroprevalence coincided with the human WNV outbreak in southern Spain in the summer of 2020, highlighting the role of red-legged partridges in the transmission/maintenance cycle and as sentinels of flaviviruses circulation.

immunology↗

bioRxiv2024

Genome admixture among four hare species in Iberia: focus on the broom hare (Lepus castroviejoi)

Pleistocene climatic fluctuations have often driven range shifts and hybridization among related species, leaving present-day genomic footprints. In the Iberian Peninsula, Lepus timidus, after its post-deglaciation retreat, has left extensive mitochondrial DNA traces in three other hare species, but the genomic correlates and underlying biogeographic scenarios are still incompletely understood. This study focuses on Lepus castroviejoi, endemic to the Cantabrian region, using its non-Iberian sister species, L. corsicanus, for comparison. By analyzing coalescent patterns from 10 genomes, we estimate that these species remained isolated since their divergence, around 50,000 years ago, consistent with their current allopatry. Further analyses with 25 additional genomes indicate that small fractions of the L. castroviejoi genome originate from L. granatensis, L. timidus, and L. europaeus (0.72%, 0.08%, and 0.04%, respectively). Introgression dating based on tract lengths suggests L. granatensis was already admixed with L. timidus when it hybridized with L. castroviejoi, which could explain the granatensis-timidus ancestry tract junctions detected in L. castroviejoi. Genomic segments with such junctions contain genes enriched for cell signaling and olfactory receptor activity, possibly facilitating genetic exchange. This research demonstrates how genomic ancestry inferences can reveal complex multiway admixture histories and illuminate past biogeographic events.

evolutionary biology↗

bioRxiv2023

The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics

A global genome database of all of Earths species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic information available. To contribute to a more complete planetary genomic database, scientists and institutions across the world have united under the Earth BioGenome Project (EBP), which plans to sequence and assemble high-quality reference genomes for all [~]1.5 million recognized eukaryotic species through a stepwise phased approach. As the initiative transitions into Phase II, where 150,000 species are to be sequenced in just four years, worldwide participation in the project will be fundamental to success. As the European node of the EBP, the European Reference Genome Atlas (ERGA) seeks to implement a new decentralised, accessible, equitable and inclusive model for producing high-quality reference genomes, which will inform EBP as it scales. To embark on this mission, ERGA launched a Pilot Project to establish a network across Europe to develop and test the first infrastructure of its kind for the coordinated and distributed reference genome production on 98 European eukaryotic species from sample providers across 33 European countries. Here we outline the process and challenges faced during the development of a pilot infrastructure for the production of reference genome resources, and explore the effectiveness of this approach in terms of high-quality reference genome production, considering also equity and inclusion. The outcomes and lessons learned during this pilot provide a solid foundation for ERGA while offering key learnings to other transnational and national genomic resource projects.

genomics↗

bioRxiv2023

Conserving genetic diversity during climate change:Niche marginality and discrepant monitoring capacity in Europe

Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. Genetic diversity has been largely neglected in biodiversity monitoring, and when addressed is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. Genetic monitoring supports the conservation and management of fisheries, game, and threatened populations. It also can contribute to the assessment of predicted and realized impacts of climate change, and their management. We report the first accounting of genetic monitoring efforts among countries in Europe (their genetic monitoring capacity, GMC) to determine where GMC suggests the combination of national infrastructure, political support and resources for continued and expanded monitoring. Overlaying GMC with areas where species ranges approach current and future climate niche limits (i.e., niche marginality) helps identify whether GMC coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area extent, financial resources, and conservation policy influence GMC, high values of which inconsistently match joint species patterns of climate niche marginality. Populations at niche margins likely hold genetic diversity that is important to adaptation to changing climate, and our results illuminate the need in Europe for expanded genetic monitoring across the climate gradients occupied by species, a need arguably greatest in southeastern European countries.

ecology↗

bioRxiv2021

Bagaza virus in wild birds, Portugal, 2021

Bagaza virus (BAGV) emerged in Spain, in 2010. Since then, BAGV was not reported in other European countries until September 2021, when BAGV was diagnosed by molecular methods in one corn bunting and several red-legged partridges, after abnormal mortality in Southern Portugal. Sequencing revealed high similarity with strains reported previously.

pathology↗

bioRxiv2021

The evolutionary pathways for local adaptation in mountain hares

Understanding the evolution of local adaptations is a central aim of evolutionary biology and key for the identification of unique populations and lineages of conservation relevance. By combining RAD sequencing and whole-genome sequencing, we identify genetic signatures of local adaptation in mountain hares (Lepus timidus) from isolated and distinctive habitats of its wide distribution: Ireland, the Alps and Fennoscandia. Demographic modelling suggested that the split of these mountain hares occurred around 20 thousand years ago, providing the opportunity to study adaptive evolution over a short timescale. Using genome-wide scans, we identified signatures of extreme differentiation among hares from distinct geographic areas that overlap with area-specific selective sweeps, suggesting targets for local adaptation. Several identified candidate genes are associated with traits related to the uniqueness of the different environments inhabited by the three groups of mountain hares, including coat colour, ability to live at high altitudes and variation in body size. In Irish mountain hares, a variant of ASIP, a gene previously implicated in introgression-driven winter coat colour variation in mountain and snowshoe hares (L. americanus), may underlie brown winter coats, reinforcing the repeated nature of evolution at ASIP moulding adaptive seasonal colouration. Comparative genomic analyses across several hare species suggested that mountain hares adaptive variants appear predominantly species-specific. However, using coalescent simulations we also show instances where the candidate adaptive variants have been introduced via introgressive hybridization. Our work shows that standing adaptive variation, including that introgressed from other species, was a crucial component of the post-glacial dynamics of species.

evolutionary biology↗

bioRxiv2020

The legacy of recurrent introgression during the radiation of hares

AO_SCPLOWBSTRACTC_SCPLOWHybridization may often be an important source of adaptive variation, but the extent and long-term impacts of introgression have seldom been evaluated in the phylogenetic context of a radiation. Hares (Lepus) represent a widespread mammalian radiation of 32 extant species characterized by striking ecological adaptations and recurrent admixture. To understand the relevance of introgressive hybridization during the diversification of Lepus, we analyzed whole exome sequences (61.7 Mb) from 15 species of hares (1- 4 individuals per species), spanning the global distribution of the genus, and two outgroups. We used a coalescent framework to infer species relationships and divergence times, despite extensive genealogical discordance. We found high levels of allele sharing among species and show that this reflects extensive incomplete lineage sorting and temporally layered hybridization. Our results revealed recurrent introgression at all stages along the Lepus radiation, including recent gene flow between extant species since the last glacial maximum, but also pervasive ancient introgression occurring since near the origin of the hare lineages. We show that ancient hybridization between northern hemisphere species has resulted in shared variation of potential adaptive relevance to highly seasonal environments, including genes involved in circadian rhythm regulation, pigmentation, and thermoregulation. Our results illustrate how the genetic legacy of ancestral hybridization may persist across a radiation, leaving a long-lasting signature of shared genetic variation that may contribute to adaptation within and among species.

evolutionary biology↗