Biology subjects

Machado, L. C.

Publications and source records attributed to Machado, L. C..

7 recordsLinked to original sources

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↗

bioRxiv2024

Genomic and phenotypic characterization of an Oropouche virus strain implicated in the 2023-24 large-scale outbreak in Brazil

The Orthobunyavirus oropoucheense in a arthropod borne zoonotic pathogen known to infect sylvatic animals and humans by means of biting midges transmission. Several large-scale human outbreaks of Oropouche virus (OROV), primarily confined to the Amazon region, were documented over the decades. However, since 2022, more widespread OROV outbreaks have been unfolding in Brazil and across South America, with cases exported to Cuba, Italy, and Germany. I In Brazil, the virus has reached and established communitary transmission in states from all major regions of the country. Here we isolated, characterized the cytopathic effect and the full genomic sequence of two OROV isolates from the current outbreak. Our data shows that OROV can readily infect and replicate in non-human primate cells, supporting the role of non-human primates as important reservoirs. Phylogenetic data supports a direct introduction of the same lineages causing the 2022-24 outbreak in Brazil from the Amazonas state, the epicenter of the epidemics in Brazil. Lastly, as case counts accumulate in the state and the Northeast region, clear evidence supports established and sustained transmission. Continued studies are critical to understand the transmission cycle in this region, the most important vectors and reservoirs, to appropriately deploy control measures.

microbiology↗

bioRxiv2023

RNA virome of sylvatic mosquitoes from northeast Brazil reveals a divergent and diverse insect-specific viral community

Mosquitoes can transmit several pathogenic viruses to humans, but their natural viral community is also composed of a myriad of other viruses such as insect-specific viruses (ISV) and those that infect symbiotic microorganisms. Besides a growing number of studies investigating the mosquito virome the majority are focused on few urban species and relatively little is known about the virome of sylvatic mosquitoes particularly in high biodiverse brazilian biomes. Here, we characterized the RNA virome of 10 sylvatic mosquitos species from Atlantic forest remains at a sylvatic-urban interface in Northeast Brazil employing a metatranscriptomic approach. A total of 16 viral families were detected. The phylogenetic reconstructions of 14 viral families revealed that the majority of the sequences are putative ISVs. The phylogenetic positioning and, in most cases, the association with a high RdRp amino acid divergence from other known viruses suggests that the viruses characterized here represent at least 34 new viral species. Therefore, the sylvatic mosquitoes viral community is majorly composed of highly divergent viruses highlighting the limited knowledge we still have about the natural virome of mosquitoes in general. Moreover, we found that none of the viruses recovered were shared between the species investigated. These findings will help to understand the interactions and coevolution between mosquitoes and viruses in nature. ImportanceMosquitoes are medically important insects as they transmit pathogenic viruses to humans and animals during blood feeding. However, their natural microbiota is also composed of a diverse set of viruses that cause no harm to the insect and other hosts, such as ISVs. In this study, we characterized the RNA virome of sylvatic mosquitoes from Northeast Brazil using unbiased metatranscriptomic sequencing and in depth bioinformatics approaches. Our analysis revealed that these mosquitoes species harbor a diverse set of highly divergent viruses and the majority comprises new viral species. Our findings revealed many new virus lineages characterized for the first time broadening our understanding about the natural interaction between mosquitoes and viruses. Lastly, it also provided several complete genomes that warrants further assessment for mosquito and vertebrate host pathogenicity and their potential interference with pathogenic arboviruses.

genomics↗

bioRxiv2022

Chikungunya virus transmission in the Southernmost state of Brazil was characterized by self-limited cases (2017 to 2019) and a larger 2021 outbreak

Chikungunya is a reemerging arthropod-borne virus that has been causing large outbreaks in the Americas. In Brazil, Asian-Caribbean and ECSA genotypes have been detected and lead to large outbreaks in several states since 2014. In Rio Grande do Sul (RS), the southernmost State, the first autochthonous cases were reported in 2016. We employed genome sequencing and epidemiological investigation to characterize the increasing CHIKF burden in RS between 2017- 2021. Distinct lineages of the ECSA genotype were responsible for human infections between 2017-2021. Until 2020, CHIKV introductions were most travel associated and transmission was limited. Then, in 2021, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage. New CHIKV outbreaks are likely to occur in the near future due to abundant competent vectors and a susceptible population, exposing more than 11 million inhabitants to an increasing infection risk.

molecular biology↗

bioRxiv2022

Evaluation of targeted oxidative stress induced by oxygen-ozone gas mixtures in vitro after ischemic induction

Encephalic vascular accident, or stroke, is the most common pathology of the central nervous system in humans. It is the second leading cause of death, as well as physical and cognitive disabilities, in developing countries. It is a vascular disorder that may present in an ischemic (more common) or hemorrhagic form. Ozone is a gas capable of oxidizing double bonds of organic molecules, thereby producing lipoperoxides and aldehydes. Stimulation of the immune and antioxidant system, and improvement in tissue vascularization and oxygenation, are few among several effects exerted by ozone. Ozone therapy has previously been shown to be effective in neuromodulation, neuroprotection, and nerve regeneration. The present study aimed to evaluate the effect of targeted mild ozone after inducing cerebral ischemia in vitro. The experiment was divided into two steps; in the first step, neuroblastoma lineage cells (SH-SY5Y) were subjected to 24 hours of hypoxia in an incubator culture chamber. Treatment with different concentrations of ozone (2-10 {micro}g/mL), followed by an 2,5-diphenyl-2H-tetrazolium bromide assay, indicated a possible neuroregenerative effect at low concentrations. The same protocol was applied to canine amniotic membrane stem cells that were evaluated via colorimetric assay spectrophotometry, fluorescence microscopy, and flow cytometry. The metabolic conditions and cellular regeneration in cells at low ozone concentrations (3-8 {micro}g/mL) correlated with lower levels of apoptosis and oxidative stress compared to cells not subjected to hypoxia. High concentrations of ozone (18-30 {micro}g/mL) promoted an increase in rate of apoptosis and cell death. Therefore, we developed a novel protocol that mimics ozone therapy for ischemic stroke, using ozonized culture medium after hypoxia induction. Although more studies are needed to open new avenues for translational medicine, we conclude that ozone has a dose-dependent hormetic effect and can reverse the effect of ischemia in vitro at low concentrations.

molecular biology↗

bioRxiv2019

Time and mode of Culicidae evolutionary history

Mosquitoes are insects of medical importance due their role as vectors of different pathogens to humans and other mammals. There is a lack of information about the evolutionary history and phylogenetic positioning of the majority of mosquitoes species. Here we sequenced the mitogenomes of mosquitoes species through low-coverage sequencing and data mining. A total of 37 draft mitogenomes were assembled representing 11 genera and 16 of those were sequenced for the first time. The recovered mitogenomes showed a coverage breadth average of 81.24%. Most of the species were clustered in monophyletic clades with other members of their own genus with exception of the Aedini tribe which was paraphyletic corroborating other findings. We established for the first time the monophyletic status of eight species from the tribe Mansoniini including both Coquillettidia and Mansonia genus and established the basal positioning of Aedeomyiini and Uranotaeniini tribes regarding the Culicinae subfamily. Molecular clock dated the Culicidae family emergence around 273 MYA and the split between Anophelinae and Culicinae subfamily around 182 MYA in the Jurassic period. Low-coverage sequencing is effective to recover mitogenomes, establish phylogenetic knowledge generating basic fundamental information to the understanding of the role of these species as pathogen vectors.

evolutionary biology↗

bioRxiv2019

First complete genome sequences of Zika virus from Midwest Brazil, 2015.

Zika virus (ZIKV) has been intensively studied in Brazil since 2015-2016 epidemics, but little is known about the virus in Midwest region of the country. We report here two ZIKV complete genomes, which were isolated during arboviral surveillance in Sinop city, southern border of the Amazonian forest, Midwest Brazil, 2015.

genomics↗