Biology subjects

Siqueira, M.

Publications and source records attributed to Siqueira, M..

7 recordsLinked to original sources

bioRxiv2026

Discovery of two potential new species and two novel bat-coronavirus subgenera (Phyllacovirus and Phyllobecovirus) in the Neotropics

Bats are major natural reservoirs for coronaviruses, yet complete viral genomes from South America remain scarce, limiting evolutionary and taxonomic understanding. Here, we conducted metatranscriptomic sequencing of coronavirus-positive bat samples collected across two ecologically distinct Brazilian biomes: the Atlantic Forest and the semi-arid Caatinga. We recovered seven complete or near-complete genomes belonging to Alphacoronavirus and Betacoronavirus. Phylogenetic and comparative similarity analyses of conserved replicase domains (3CLpro, NiRAN, RdRp, ZBD, HEL1), following International Committee on Taxonomy of Viruses (ICTV) demarcation criteria, revealed significant viral diversity. Within Alphacoronavirus, two genomes from Atlantic Forest phyllostomid bats (Artibeus lituratus and Carollia perspicillata) formed a deeply divergent sister lineage to Amalacovirus, exhibiting a mean amino acid similarity of 76.7% with the reference genome. Within Betacoronavirus, one genome from a Caatinga phyllostomid bat (Artibeus planirostris) clustered within the recently described Ambecovirus clade, displaying 75.9% mean amino acid similarity with mormoopid-associated reference sequences. Based on these divergence levels and non-recombinant genomic architectures, we propose two novel candidate subgenera, Phyllacovirus and Phyllobecovirus, alongside potential novel viral species. Furthermore, our findings demonstrate strong host-associated structuring and biogeographical partitioning of viral lineages across Neotropical biomes. Overall, this study expands the genomic landscape of South American bat coronaviruses and underscores the importance of continuous genomic surveillance at human-wildlife interfaces.

genomics↗

bioRxiv2025

Genomics insights reveal multi-year maintenance of a new Deltacoronavirus infecting Seabirds from the Cagarras Island Archipelago Natural Monument, Brazil

Previous studies have identified various pathogens in seabirds, notably coronaviruses (CoVs) and influenza A viruses (IAVs), due to their potential to cause significant morbidity and mortality. The Cagarras Island Archipelago Natural Monument, located near Rio de Janeiro, Brazil, serves as nesting site for two species, the magnificent frigatebird (Fregata magnificens) and the brown booby (Sula leucogaster). Despite its ecological importance, no prior studies have investigated viral infections in these species, which share habitat interfaces with densely populated human areas. To address this gap, we sampled and tested seabirds for CoVs and IAVs from January 2022 to April 2024. Birds were captured and identified by species, age, and sex. Oropharyngeal and cloacal swabs, as well as blood samples, were collected. Viral RNA was extracted using the QIAamp Viral RNA Mini Kit, and the presence of IAVs was screened via real-time RT-PCR, while CoVs were screened using semi-nested RT-PCR. Sanger and metatranscriptomic sequencing were performed to identify viral strains and assess phylogenetic relationships. Of the 153 seabirds sampled, CoVs were detected in 6 individuals (9.1%) of F. magnificens and 16 individuals (18.4%) of S. leucogaster. No IAVs were found in either oropharyngeal or cloacal swabs, and all serum samples were negative for the presence of antibodies against the virus. We recovered two full deltacoronavirus genomes and eight additional draft genomes from S. leucogaster samples obtained from distinct sampling expeditions and additional enteroviruses, passeriviruses, and picornaviruses. Phylogenetic analysis revealed that the detected CoVs are closely related to avian deltacoronaviruses from environmental samples of S. leucogaster in the Sao Pedro and Sao Paulo Archipelago, indicating potential viral exchange between these seabird populations living at these distant islands. Moreover, multiple detections in different individuals at different time points are associated with specific Spike NTD deletions that have been shown to accumulate in immune escape lineages, supporting the long-term maintenance through new infections and reinfection of this virus in these bird populations. This is the first detection of CoVs in F. magnificens, highlighting their circulation in marine ecosystems. Further research is needed to understand the ecological and epidemiological implications, including potential cross-species transmission.

microbiology↗

bioRxiv2024

High Pathogenicity Avian Influenza Virus (HPAIV) H5N1 clade 2.3.4.4b recovered from a kelp gull (Larus dominicanus) in the South Shetland Islands, Antarctica

Whole-genome analysis of the earliest-detected High Pathogenicity Avian Influenza Virus (HPAIV) H5N1 clade 2.3.4.4b detected in Hannah Point, Antarctica (January 2024) reveals close relatedness to strains that circulated in pinnipeds and seabirds along the Atlantic coast of South America during the second half of 2023.

molecular biology↗

bioRxiv2024

Detection of Deltacoronavirus in Environmental Fecal Samples from Seabirds in the Saint Peter and Saint Paul Archipelago, central equatorial Atlantic Ocean

This study investigates the presence of avian coronaviruses (CoVs), influenza A viruses (IAVs), and Avian rotaviruses (RVs) group A in seabird populations inhabiting the Saint Peter and Saint Paul Archipelago (SPSPA), an isolated and remote oceanic island situated in the equatorial region of the Atlantic Ocean. In July 2022, 95 environmental fecal samples were collected from seabird colonies and screened for the viruses by quantitative one-step real-time RT-PCR (IAVs and RVs), by the conventional pancoronavirus RT-PCR protocols and metatranscriptomics of a positive sample. Four environmental feces samples tested positive for CoVs. Avian IAVs and RVs were not detected. Phylogenetic analysis revealed CoVs closely related to avian deltacoronaviruses previously identified in waterbirds from Asia and Australia. We could not recover the CoV by metatranscriptomics but we recovered a single viral contig of an avian enterovirus. The findings contribute valuable insights into virus dynamics among seabird populations, laying the groundwork for future investigations in this field.

molecular biology↗

bioRxiv2024

Detection and full genome sequencing of a Deltacoronavirus and other bird associated viruses from feces of the kelp gull (Larus dominicanus) sampled at the South Shetland Islands Antarctica.

Bird species are known to be the main reservoir of a range of respiratory viruses such as Influenza, Newcastle and Coronaviruses. Migratory birds are particularly important for the maintenance and long distance spread of the virus to wild bird and poultry species but eventually to mammal species as well. Antarcticas pristine environment and wildlife is of immense biological value, but the spread of such deadly viruses pose a substantial threat to the regions fragile ecosystems. To investigate the presence of respiratory viruses in the region we sampled feces of different wild migratory birds at various localities in the South Shetland Islands in the Antarctic summer of 2023 and screened them for coronaviruses (CoVs) and influenza A virus (IAV). Viral screening was performed by the conventional pancoronavirus RT-PCR protocol (CoVs), by quantitative one-step real-time RT-PCR (IAVs) followed by metatranscriptomic sequencing of positive samples. During January and February of 2023, we collected and examined a total of 243 fecal samples representing Stercorarius spp (N=5), Larus dominicanus (N=16), Phalacrocorax bransfieldensis (N=3), Pygoscelis adeliae (N=19), Pygoscelis antarcticus (N=38), Pygoscelis papua (N=139), Pygoscelis spp (N=23). All tested samples were negative for influenza A and one sample from the colony of L. dominicanus at Keller Peninsula, King George Island, tested positive for CoVs. Metatranscriptomic sequencing recovered a full deltaCoV genome. Nucleotide and amino acid distance analysis revealed that the deltacoronavirus detected belongs to subgenus Buldecovirus and to the novel wild bird deltaCoV clade previously identified infecting Antarctica penguins. The identified deltaCov is most closely related to a deltacoronavirus previously identified 2014 in P. papua penguin sampled at Isla Kopaitik, Base OHiggin suggesting a potential cross species transmission. The presence of CoVs in Antarctic migratory seabirds raises concerns about their impact on the wild bird population in Antarctica and their potential role in virus dispersion through intra and intercontinental migratory routes. These findings contribute valuable insights into virus dynamics among seabird populations, laying the groundwork for future investigations in this field and warning of the importance of viral surveillance on the Antarctic fauna. RepositoriesThe raw reads were submitted to NCBI Sequence Read Archive (SRA) database and are available under project number: PRJNA1160912 and Run Accessions: SRR30664529 and SRR30664530. Impact statementThis study provides insights into the presence of respiratory viruses, specifically coronaviruses (CoVs), in Antarctic seabirds. By detecting a novel wild bird deltacoronavirus in gulls population in the South Shetland Islands, our research contributes to the growing body of literature on viral transmission in remote ecosystems. The findings highlight the potential of migratory birds to act as reservoirs and vectors of viruses in the Antarctic region and underscores the urgent need for continued viral surveillance.

genomics↗

bioRxiv2022

SARS-CoV-2 infection of human brain microvascular endothelial cells leads to inflammatory activation through NF-κB non-canonical pathway and mitochondrial remodeling

Neurological effects of COVID-19 and long-COVID-19 as well as neuroinvasion by SARS-CoV-2 still pose several questions and are of both clinical and scientific relevance. We described the cellular and molecular effects of the human brain microvascular endothelial cells (HBMECs) in vitro infection by SARS-CoV-2 to understand the underlying mechanisms of viral transmigration through the Blood-Brain Barrier. Despite the low to non-productive viral replication, SARS-CoV-2-infected cultures displayed increased apoptotic cell death and tight junction protein expression and immunolocalization. Transcriptomic profiling of infected cultures revealed endothelial activation via NF-{kappa}B non-canonical pathway, including RELB overexpression, and mitochondrial dysfunction. Additionally, SARS-CoV-2 led to altered secretion of key angiogenic factors and to significant changes in mitochondrial dynamics, with increased mitofusin-2 expression and increased mitochondrial networks. Endothelial activation and remodeling can further contribute to neuroinflammatory processes and lead to further BBB permeability in COVID-19.

cell biology↗

bioRxiv2018

Radial Glia cell infection by Toxoplasma gondii disrupts brain microvascular endothelial cell integrity

Congenital toxoplasmosis is a parasitic disease that occurs due vertical transmission of the protozoan Toxoplasma gondii (T. gondii) during pregnancy. The parasite crosses the placental barrier and reaches the developing brain, infecting progenitor, glial, neuronal and vascular cell types. Although the role of Radial glia (RG) neural stem cells in the development of the brain vasculature has been recently investigated, the impact of T. gondii infection in these events is not yet understood. Herein, we studied the role of T. gondii infection on RG cell function and its interaction with endothelial cells. By infecting isolated RG cells with T. gondii tachyzoites, we observed reduced cell proliferation and neurogenesis without affecting gliogenesis levels. Conditioned medium (CM) from RG control cultures increased ZO-1 and {beta}-catenin protein levels and organization on endothelial bEnd.3 cells membranes, which was completely impaired by CM from infected RG, resulting in decreased transendothelial electrical resistance (TEER). Cytokine Bead Array and ELISA assays revealed the presence of increased levels of the pro-inflammatory cytokine IL-6 and reduced levels of anti-inflammatory cytokine TGF-{beta}1 in CM from T.gondii-infected RG cells. Treatment with recombinant TGF-{beta}1 concomitantly with CM from infected RG cultures led to restoration of ZO-1 staining in bEnd.3 cells. Our results suggest that infection of RG cells by T. gondii modulate cytokine secretion, which might contribute to endothelial loss of barrier properties, thus leading to impairment of neurovascular interaction establishment.

neuroscience↗