Neural Infection by Oropouche Virus in Adult Human Brain Slices Induces an Inflammatory and Toxic Response

Epidemiology, transmission dynamics, treatment strategies, and future perspectives on Oropouche virus

Oropouche virus (OROV), a mosquito-borne pathogen primarily found in the Amazon basin, has attracted increasing attention due to its expanding geographical spread and recurrent outbreaks. First identified in 1955, OROV causes Oropouche fever, a febrile illness with clinical features that often overlap with those of other arboviral infections, posing significant diagnostic challenges. Arboviruses such as dengue, chikungunya, zika, and yellow fever also circulate in the same regions of South and Central America, further complicating the clinical differentiation of OROV from these infections. The primary vector for OROV in urban areas is Culicoides paraensis midges, but the virus also maintains a sylvatic transmission cycle involving Aedes serratus and Coquillettidia venezuelensis mosquitoes, along with wild vertebrate reservoirs such as sloths, non-human primates, and birds. Moreover, in 2024, over 10,000 OROV cases were reported including in previously unaffected regions with Brazil recording 5,407 cases since 2015, while recent fatalities linked to severe coagulopathy, liver failure, and adverse pregnancy outcomes remain under investigation. Currently, no specific antiviral treatments are available for OROV, and the diagnostic tools are limited, highlighting the urgent need for improved management strategies. Given the increasing number of OROV cases, there is a clear need to strengthen surveillance efforts and accelerate the development of vaccines and therapeutic interventions. This review delves into the multi-faceted approach to control OROV, incorporating surveillance, antiviral therapy, and vaccine development to mitigate the impact of this emerging pathogen. Furthermore, it provides a comprehensive overview of the epidemiology and future potential antiviral candidates and challenges in current therapeutic approaches.

MyD88 signalling in B cells and antibody responses during Oropouche virus-induced neurological disease in mice

BACKGROUND

Oropouche virus (OROV) is a neglected insect-borne orthobunyavirus that causes a febrile illness, neurological disease, and pregnancy complications in humans across an endemic area spanning South and Central America. The host factors associated with disease pathogenesis have nonetheless remained obscure, and little is known about the immune determinants of protection against OROV.

METHODS

We tracked morbidity, mortality, viral loads, and serum neutralisation in wild-type (WT), Rag1-/-, CD19-Cre+Ifnarfl, and CD19-Cre+MyD88fl mice and performed immunophenotyping experiments, passive serum transfers, and adoptive cell transfers to determine how early antibody responses and B cell subsets control viral replication and dissemination to the central nervous system after infection with OROV.

FINDINGS

In line with a protective role for B cells, WT mice efficiently produced OROV-specific antibodies within 6 days of infection. Serum transfer containing neutralising IgM from WT to Rag1-/- mice prevented neurological disease in OROV-challenged mice. CD19-Cre+MyD88fl mice but not CD19-Cre+Ifnarfl mice were vulnerable to neurological disease and produced lower titres of OROV-specific antibodies that exhibited suboptimal neutralisation and potency compared with MyD88-sufficient mice. CD19-Cre+MyD88fl mice also presented with reduced numbers of marginal zone B (MZB) cells and plasmablasts after infection, which were associated with high viral burdens and lethality. Adoptive transfer of MZB cells from WT mice protected CD19-Cre+MyD88fl mice and partially protected Rag1-/- mice from lethal infection with OROV.

INTERPRETATION

Early MyD88 signalling in B cells is required for optimal antibody responses that limit viral replication and neurological disease in mice infected with OROV.

FUNDING

São Paulo Research Foundation (FAPESP), National Council for Scientific and Technological Development (CNPq), Coordination for the Improvement of Higher Education Personnel (CAPES), Unicamp Research Affairs Office, PIPAE University of São Paulo, Wellcome Trust, and National Institute of Science and Technology on Photonics Applied to Cell Biology (INFABIC, Unicamp).

Lysergol exerts potent antiviral activity against the emerging Oropouche virus in vitro

Oropouche virus (OROV) has caused a new outbreak, with thousands of cases of febrile disease in South and Central America, including regions where the virus was not detected before. Oropouche fever is a neglected mosquito-borne disease that still lacks options for antiviral treatment. We developed a high-throughput screening phenotypic assay using human hepatocyte-derived HuH-7.0 cells to screen over 7700 compounds against OROV infection. We identified 13 hit compounds that were protective against OROV-induced cytopathic effect in cell culture, of which 3 were confirmed: lysergol, amiloride hydrochloride, and pyridostatin TFA, with EC50 values below 2 μM. Orthogonal assays indicate that both lysergol and pyridostatin present antiviral activity against OROV in HuH-7.0 and T24 cell lines, but lysergol is far more potent, causing up to a 100,000-fold reduction in viral load in the low micromolar range. Mechanistic studies indicate that the antiviral effect of lysergol affects early stages of viral replication, and that lysergol is also active against a recently isolated OROV strain. In conclusion, our phenotypical screening campaign led to the identification of a first-in-class compound with potent antiviral activity against the emerging OROV in cell culture. We conclude that high-throughput screening assays can be implemented in response to the emergence of arboviruses and accelerate the discovery of candidate treatments.

Maternal and Fetal Implications of Oropouche Fever, Espírito Santo State, Brazil, 2024

Reemergence of Oropouche fever in Brazil raises concerns about potential risks for infection in pregnancy. We describe a case series of Oropouche fever in pregnant women and their neonates in Espírito Santo State, Brazil, in 2024. Of 73 pregnancies, 15 pregnancies concluded by the end of the study period; of those, 14 resulted in live births and 1 in spontaneous abortion. Placental reverse transcription PCR tests were positive for Oropouche virus RNA in 5 infections in the third trimester. Two infections occurred in the first trimester, resulting in 1 spontaneous abortion and 1 live birth with corpus callosum dysgenesis. Of 13 infections that occurred in the third trimester, 1 showed possible intrapartum transmission with clinical manifestations in the neonate, whereas the others were asymptomatic. We found no anomalies in third-trimester infections. These findings suggest possible vertical transmission of Oropouche virus and a potential link with spontaneous abortion or malformation.

A Comprehensive Review of the Neglected and Emerging Oropouche Virus

Oropouche virus (OROV) is a neglected and emerging arbovirus that infects humans and animals in South and Central America. OROV is primarily transmitted to humans through the bites of infected midges and possibly some mosquitoes. It is the causative agent of Oropouche fever, which has high morbidity but low mortality rates in humans. The disease manifests in humans as high fever, headache, myalgia, arthralgia, photophobia, and, in some cases, meningitis and encephalitis. Additionally, a recent report suggests that OROV may cause fetal death, miscarriage, and microcephaly in newborns when women are infected during pregnancy, similar to the issues caused by the Zika virus (ZIKV), another mosquito-borne disease in the same regions. OROV was first reported in the mid-20th century in the Amazon basin. Since then, over 30 epidemics and more than 500,000 infection cases have been reported. The actual case numbers may be much higher due to frequent misdiagnosis, as OROV infection presents similar clinical symptoms to other co-circulating viruses, such as dengue virus (DENV), chikungunya virus (CHIKV), ZIKV, and West Nile virus (WNV). Due to climate change, increased travel, and urbanization, OROV infections have occurred at an increasing pace and have spread to new regions, with the potential to reach North America. According to the World Health Organization (WHO), over 10,000 cases were reported in 2024, including in areas where it was not previously detected. There is an urgent need to develop vaccines, antivirals, and specific diagnostic tools for OROV diseases. However, little is known about this surging virus, and no specific treatments or vaccines are available. In this article, we review the most recent progress in understanding virology, transmission, pathogenesis, diagnosis, host-vector dynamics, and antiviral vaccine development for OROV, and provide implications for future research directions.

Oropouche Virus: Implications for Transfusion Services

In 2024, a novel recombinant of the Oropouche virus emerged as a potential threat. This virus has caused a significant outbreak in Brazil and Cuba, with imported cases subsequently reported in the USA and Europe. This review summarises the existing knowledge on the Oropouche virus, and discusses potential risk mitigation strategies for the transfusion community.

Neurological Performance and Clinical Outcomes Related to Patients With Oropouche-Associated Guillain-Barré Syndrome

BACKGROUND AND AIMS

A recent study reported that Oropouche virus (OROV) infection may play a role in the etiology of Guillain-Barré syndrome. We aimed to identify the neurological performance, disease-modifying therapies, and clinical outcomes related to patients with Oropouche-associated Guillain-Barré syndrome admitted to the critical care unit.

METHODS

This was an analysis of 210 patients diagnosed with Guillain-Barré syndrome and suspicion of Oropouche viral infection admitted to the critical care units from June 2024 to September 2024 using the national administrative healthcare data. OROV was identified by reverse-transcriptase-polymerase-chain-reaction. Patients with Guillain-Barré syndrome and Oropouche infection were compared with those without Oropouche infection in terms of demography features, neurological performance, disease-modifying therapies, and clinical outcomes.

RESULTS

Most patients had a severe disease. Mechanical ventilation was required in 28.6%. Overall mortality rate was 14.3%. The median time from onset of weakness to intensive care unit discharge, and the median time from hospital admission to intensive care unit discharge was 18 days (IQR: 13-24.3 days) and 13 days (IQR: 9-19 days), respectively. Oropouche viral infection was detected in 43 (20.5%) patients. There were no differences among patients with and without Oropouche viral infection regarding general characteristics, neurological performance, disease-modifying therapies, and outcomes. After adjusting for confounders in multivariate logistic regression analysis, Oropouche viral infection (OR: 1.94; 95% CI: 0.72-5.20; p = 0.189) was not related to increased mortality.

INTERPRETATION

Oropouche viral infection does not modify the clinical course, disease severity, and outcomes of patients with Guillain-Barré syndrome.

A View on the Emerging Concern of Oropouche Fever in Brazil and Its Diagnosis

Oropouche fever has gained prominence due to its outbreaks and health consequences, particularly in Latin American countries. In addition to the more common symptoms of fever and nausea, Oropouche has been reported to cause neurological and gastrointestinal problems. However, Oropouche remains a neglected disease that needs improved detection methods. The purpose of this letter is to raise awareness of this infectious disease and the methods that can be used to detect and ultimately control it.

Newborns with microcephaly in Brazil and potential vertical transmission of Oropouche virus: a case series

BACKGROUND

Oropouche fever, an orthobunyavirus disease endemic in Brazilian Amazon, has caused many febrile epidemics. In 2024, an epidemic of Oropouche fever spread in Brazil, with more than 7930 cases reported between Jan 1 and Aug 31. Infections in pregnant people have suggested the possibility of negative fetal consequences, therefore we tested newborns with microcephaly for known congenital pathogens and Oropouche virus (OROV).

METHODS

In this case series, we assessed historical cases of infants born with microcephaly, arthrogryposis, and other congenital malformations without a confirmed cause and their mothers for potential OROV congenital infections. The study population consisted of infants born in Brazil with samples from 2015-21 and 2024. Serum and cerebrospinal fluid (CSF) from this case series were analysed for: syphilis, toxoplasmosis, rubella, cytomegalovirus, herpes simplex, HIV, Zika, dengue, and chikungunya. Individuals that were negative for these pathogens were then tested for OROV. Pathogen testing included ELISA and haemagglutination inhibition testing for antibodies and RT-PCR for virus RNA.

FINDINGS

We tested 68 samples from 65 historical cases of congential malformations and three cases from 2024. All cases were from ten states in Brazil. Three historical cases tested positive for OROV and 62 historical cases tested negative. The three cases from 2024 all tested positive for OROV. Of the positive cases, five were female and one was male. Not all pathogens were tested for each case, and some did not have maternal samples available. One of the newborns (case 6) died aged 47 days and tissue samples were tested by real-time RT-PCR, histopathology, and immunohistochemistry assays. One other newborn died in 2016 but no post-mortem samples were available. OROV IgM was detected in five of five newborn CSF samples, and five of five newborn serum samples. Four of five maternal serum samples were positive for OROV IgM. One of four newborn CSF samples (case 6 at age 44 days) was OROV positive by real-time RT-quantitative PCR and 0 of four newborn serum samples were positive, as were 0 of three maternal serum samples. Case 6 had major tissue changes of the brain macroscopically and microscopically, including necrotic and apoptotic changes of neurons, microglia and astrocytes, vacuolisation, and tissue atrophy. OROV RNA was detected in brain, lungs, kidney, CSF, and pleural fluid; OROV antigens were found in CNS, liver, kidney, heart, and lung, mainly in neurons and microglia and also in endothelial cells, suggesting vasculitis.

INTERPRETATION

We detected OROV IgM in six of 68 newborns with microcephaly of unknown cause. One infant who died had OROV RNA and antigen in several tissues, including the brain. The possibility of OROV vertical transmission and potential fetal harm must be investigated with urgency. The evidence presented here does not completely confirm vertical transmission or congenital malformations due to OROV, but thorough case finding and detailed investigation of maternal or fetal OROV infection is a priority.

FUNDING

Evandro Chagas Institute, Secretaria de Vigilância em Saúde e Ambiente, and Ministry of Health and National Institute of Science and Technology for Emerging and Reemerging Viruses.

Human brain tissue cultures: a unique ex vivo model to unravel the pathogenesis of neurotropic arboviruses

Arboviruses are transmitted by arthropods, and their spread from endemic to nonendemic regions has been accelerated by deforestation, climate change, and global mobility. Arbovirus infection in human results in symptoms ranging from mild to life-threatening, with the impairment of central nervous system functions being reported in severe cases. Despite its clinical relevance, the mechanisms by which arboviruses led to neural dysfunction are still poorly understood. The lack of a widespread human central nervous system model to study the virus-host interaction challenges the advance of our knowledge on these mechanisms. In this context, human brain-derived ex vivo models have the advantage of preserving cellular diversity, cell connections, and tissue cytoarchitecture found in human brain, raising them as a powerful strategy to elucidate the cellular-molecular alterations underlying brain diseases. Here, we review recent advances in the field of neurotropic arboviruses obtained using ex vivo human brain tissue as the experimental model.

Ex vivo study of neuroinvasive and neurotropic viruses: what is current and what is next

Numerous pathogens, including viruses, enter the central nervous system and cause neurological disorders, such as encephalitis. Viruses are the main etiologic agents of such neurological diseases, and some of them cause a high death toll worldwide. Our knowledge about neuroinvasive and encephalitogenic virus infections is still limited due to the relative inaccessibility of the brain. To mitigate this shortcoming, neural ex vivo models have been developed and turned out to be of paramount importance for understanding neuroinvasive and neurotropic viruses. In this review, we describe the major ex vivo models for the central nervous system, including neural cultures, brain organoids, and organotypic brain cultures. We highlight the key findings from these models and illustrate how these models inform on viral processes, including neurotropism, neuroinvasion, and neurovirulence. We discuss the limitations of ex vivo models, highlight ongoing progress, and outline next-generation ex vivo models for virus research at the interface of neuroscience and infectious diseases.

Genomic Epidemiology of 2023-2024 Oropouche Outbreak in Iquitos, Peru reveals independent origin from a concurrent outbreak in Brazil

Oropouche virus is an arbovirus endemic to the Americas. Periodic outbreaks have occurred since its description in 1955. In late 2023, an outbreak occurred in Peru, centered in and around Iquitos in the Eastern Peruvian Amazon. An existing acute febrile illness (AFI) surveillance program was able to document its emergence and characterize arthralgia and dysuria and the absence of diarrhea as distinctive clinical features of Oropouche virus-associated febrile illness relative to other causes of AFI. Sequencing of isolates from the outbreak demonstrated that strains from this region were distinct from those causing disease in Brazil, despite the large-scale movement of people along the Amazon corridor, but highly similar to strains from Colombia and Ecuador. Our findings suggest that the current outbreak in South America is fundamentally multifocal in origin and not the result of geographic spread from Brazil, which experienced an outbreak between 2022 and 2024.

Oropouche Virus: An Emerging Neuroinvasive Arbovirus

Oropouche virus (OROV) is an arthropod-borne virus (arbovirus) in the Orthobunyavirus genus and Peribunyaviridae viral family that is endemic to parts of South America, Central America, and the Caribbean. It has recently emerged in Cuba, and travel-imported cases are recently being reported in the United States and Europe. Typically maintained in a sylvatic cycle between certain forest sloths, non-human primates, birds, and mosquitoes, OROV disease outbreaks can occur in an urban cycle between certain biting midges and/or mosquitoes and humans. Clinically, approximately 60% of infections are symptomatic with an abrupt fever and non-specific influenza-like illness within 3 to 10 days. Many initial OROV infections can present similarly to chikungunya, dengue, and Zika virus infections. Interestingly, OROV infections can follow a biphasic course with recurrence of symptoms approximately 1 week after initial symptom onset. Concerningly, similar to Zika virus, it appears that vertical transmission of OROV may occur with potentially adverse effects on fetal development including miscarriages. Neuroinvasion of OROV occurs in animal models, and human cases of meningitis, encephalitis, and peri-infectious Guillain-Barré syndrome have all been reported. Diagnosis is either through detection of OROV nucleic acid, OROV immunoglobulin M, or OROV neutralizing antibodies in the serum and/or cerebrospinal fluid. No antiviral treatments are available, and there are no current vaccines. Preventing mosquito and biting midge bites is key. Neurologists should be aware of and report any potential neuroinvasive OROV disease cases to local/state/territorial health departments. ANN NEUROL 2024.

New insights into Oropouche: expanding geographic spread, mortality, vertical transmission, and birth defects

Oropouche virus (OROV) is an arbovirus transmitted by midges that is now emerging outside the Amazon region. For the first time, fatal cases were reported, and possible vertical transmission of OROV is under investigation. Knowledge gaps remain concerning the natural history of OROV infection, host immune response and vector competence.

Characterization of neural infection by Oropouche orthobunyavirus

Oropouche fever is a re-emerging global viral threat caused by infection with Oropouche orthobunyavirus (OROV). While disease is generally self-limiting, historical and recent reports of neurologic involvement highlight the importance of understanding the neuropathogenesis of OROV. In this study, we characterize viral replication kinetics in neurons and microglia derived from immortalized, primary, and induced pluripotent stem cell-derived cells, which are all permissive to infection. We demonstrate that ex vivo rat brain slice cultures can be infected by OROV and produce antiviral cytokines and chemokines, including IL-6, TNF-α and IFN-β, which introduces an additional model to study viral kinetics in the central nervous system. These findings provide additional insight into OROV neuropathogenesis and in vitro modeling strategies for a newly re-emerging arbovirus.

A bibliometric analysis of Oropouche virus

Objectives

Oropouche virus (OROV) causes systemic infections including the nervous and blood systems, posing a significant and growing public health challenge. However, a comprehensive review of the bibliometric analysis of OROV is still lacking. Therefore, the objective of this study was to provide insight into the research dynamics and current hotspots of OROV.

Methods

This study used bibliometric analysis to explore the current status of research related to OROV. 148 publications from 1961 to 2024 were retrieved from the Scopus database. Countries, authors, institutions, journals, references, and keywords were visualized using VOSviewer, CiteSpace, R studio, and Bibliometrix. Microsoft Excel was used for statistical analysis.

Results

Brazil is the country with the highest number of publications, total cited frequency, and the most extensive international collaboration. The most popular journal in this field is the American Journal of Tropical Medicine and Hygiene. Instituto Evandro Chagas is the institution with the highest number of publications, and Eurico Arruda is involved in the highest number of publications. Keyword co-occurrence analysis showed that Oropouche bunyavirus, virology, bunyavirus, priority journal, and nucleotide sequence are the main research hotspots in this field.

Conclusion

Our study provides a comprehensive overview of the research trends and key areas of focus in OROV. The field is currently experiencing rapid growth, as evidenced by the rising number of annual publications, which not only highlights increased research activity but also lays a solid foundation for further in-depth investigations. This trend offers valuable insights for developing effective strategies for outbreak prevention and control in public health. Presently, researchers are concentrating on the detailed study of Bunyavirus infections, employing both virological and genetic approaches to elucidate their complex pathogenic mechanisms.

Oropouche Virus: An Emerging Orthobunyavirus

On 2 February 2024, the Pan American Health Organization/World Health Organization issued an epidemiological alert on rising Oropouche virus (OROV) infections in South America. By 3 August 2024, this alert level had escalated from medium to high. OROV has been a public health concern in Central and South America since its emergence in Brazil in the 1960s. However, the 2024 outbreak marks a turning point, with the sustained transmission in non-endemic regions of Brazil, local transmission in Cuba, two fatalities and several cases of vertical transmission. As of the end of August 2024, 9852 OROV cases have been confirmed. The 2024 OROV outbreak underscores critical gaps in our understanding of OROV pathogenesis and highlights the urgent need for antivirals and vaccines. This review aims to provide a concise overview of OROV, a neglected orthobunyavirus.

Emergence of Oropouche fever in Latin America: a narrative review

Since its discovery in 1955, the incidence and geographical spread of reported Oropouche virus (OROV) infections have increased. Oropouche fever has been suggested to be one of the most important vector-borne diseases in Latin America. However, both literature on OROV and genomic sequence availability are scarce, with few contributing laboratories worldwide. Three reassortant OROV glycoprotein gene variants termed Iquitos, Madre de Dios, and Perdões virus have been described from humans and non-human primates. OROV predominantly causes acute febrile illness, but severe neurological disease such as meningoencephalitis can occur. Due to unspecific symptoms, laboratory diagnostics are crucial. Several laboratory tests have been developed but robust commercial tests are hardly available. Although OROV is mainly transmitted by biting midges, it has also been detected in several mosquito species and a wide range of vertebrate hosts, which likely facilitates its widespread emergence. However, potential non-human vertebrate reservoirs have not been systematically studied. Robust animal models to investigate pathogenesis and immune responses are not available. Epidemiology, pathogenesis, transmission cycle, cross-protection from infections with OROV reassortants, and the natural history of infection remain unclear. This Review identifies Oropouche fever as a neglected disease and offers recommendations to address existing knowledge gaps, enable risk assessments, and ensure effective public health responses.

Adult Human Brain Tissue Cultures to Study NeuroHIV

HIV-associated neurocognitive disorders (HAND) persist under antiretroviral therapy as a complex pathology that has been difficult to study in cellular and animal models. Therefore, we generated an ex vivo human brain slice model of HIV-1 infection from surgically resected adult brain tissue. Brain slice cultures processed for flow cytometry showed >90% viability of dissociated cells within the first three weeks in vitro, with parallel detection of astrocyte, myeloid, and neuronal populations. Neurons within brain slices showed stable dendritic spine density and mature spine morphologies in the first weeks in culture, and they generated detectable activity in multi-electrode arrays. We infected cultured brain slices using patient-matched CD4+ T-cells or monocyte-derived macrophages (MDMs) that were exposed to a GFP-expressing R5-tropic HIV-1 in vitro. Infected slice cultures expressed viral RNA and developed a spreading infection up to 9 days post-infection, which were significantly decreased by antiretrovirals. We also detected infected myeloid cells and astrocytes within slices and observed minimal effect on cellular viability over time. Overall, this human-centered model offers a promising resource to study the cellular mechanisms contributing to HAND (including antiretroviral toxicity, substance use, and aging), infection of resident brain cells, and new neuroprotective therapeutics.

Organotypic culture of human brain explants as a preclinical model for AI-driven antiviral studies

Viral neuroinfections represent a major health burden for which the development of antivirals is needed. Antiviral compounds that target the consequences of a brain infection (symptomatic treatment) rather than the cause (direct-acting antivirals) constitute a promising mitigation strategy that requires to be investigated in relevant models. However, physiological surrogates mimicking an adult human cortex are lacking, limiting our understanding of the mechanisms associated with viro-induced neurological disorders. Here, we optimized the Organotypic culture of Post-mortem Adult human cortical Brain explants (OPAB) as a preclinical platform for Artificial Intelligence (AI)-driven antiviral studies. OPAB shows robust viability over weeks, well-preserved 3D cytoarchitecture, viral permissiveness, and spontaneous local field potential (LFP). Using LFP as a surrogate for neurohealth, we developed a machine learning framework to predict with high confidence the infection status of OPAB. As a proof-of-concept, we showed that antiviral-treated OPAB could partially restore LFP-based electrical activity of infected OPAB in a donor-dependent manner. Together, we propose OPAB as a physiologically relevant and versatile model to study neuroinfections and beyond, providing a platform for preclinical drug discovery.

Oropouche virus: A neglected global arboviral threat

The Oropouche virus is an important arthropod-borne virus in the Peribunyaviridae family that can cause febrile illnesses, and it is widely distributed in tropical regions such as Central and South America. Since the virus was first identified, a large number of related cases are reported every year. No deaths have been reported to date, however, the virus can cause systemic infections, including the nervous and blood systems, leading to serious complications. The transmission of Oropouche virus occurs through both urban and sylvatic cycles, with the anthropophilic biting midge Culicoides paraensis serving as the primary vector in urban areas. Direct human-to-human transmission of Oropouche virus has not been observed. Oropouche virus consists of three segments, and the proteins encoded by the different segments enables the virus to replicate efficiently in the host and to resist the host's immune response. Phylogenetic analyses showed that Oropouche virus sequences are geographically distinct and have closer homologies with Iquitos virus and Perdoes virus, which belong to the family Peribunyaviridae. Despite the enormous threat it poses to public health, there are currently no licensed vaccines or specific antiviral treatments for the disease it causes. Recent studies have utilised imJatobal virusmunoinformatics approaches to develop epitope-based peptide vaccines, which have laid the groundwork for the clinical use of vaccines. The present review focuses on the structure, epidemiology, immunity and phylogeny of Oropouche virus, as well as the progress of vaccine development, thereby attracting wider attention and research, particularly with regard to potential vaccine programs.

NMDA glutamate receptor antagonist MK-801 induces proteome changes in adult human brain slices which are partially counteracted by haloperidol and clozapine

Deciphering the molecular pathways associated with N-methyl-D-aspartate receptor (NMDAr) hypofunction and its interaction with antipsychotics is necessary to advance our understanding of the basis of schizophrenia, as well as our capacity to treat this disease. In this regard, the development of human brain-derived models that are amenable to studying the neurobiology of schizophrenia may contribute to filling the gaps left by the widely employed animal models. Here, we assessed the proteomic changes induced by the NMDA glutamate receptor antagonist MK-801 on human brain slice cultures obtained from adult donors submitted to respective neurosurgery. Initially, we demonstrated that MK-801 diminishes NMDA glutamate receptor signaling in human brain slices in culture. Next, using mass-spectrometry-based proteomics and systems biology in silico analyses, we found that MK-801 led to alterations in proteins related to several pathways previously associated with schizophrenia pathophysiology, including ephrin, opioid, melatonin, sirtuin signaling, interleukin 8, endocannabinoid, and synaptic vesicle cycle. We also evaluated the impact of both typical and atypical antipsychotics on MK-801-induced proteome changes. Interestingly, the atypical antipsychotic clozapine showed a more significant capacity to counteract the protein alterations induced by NMDAr hypofunction than haloperidol. Finally, using our dataset, we identified potential modulators of the MK-801-induced proteome changes, which may be considered promising targets to treat NMDAr hypofunction in schizophrenia. This dataset is publicly available and may be helpful in further studies aimed at evaluating the effects of MK-801 and antipsychotics in the human brain.

OROPOUCHE VIRUS: MORE QUESTIONS THAN ANSWERS

Oropouche virus (genus Orthobunyavirus, family Peribunyaviridae) is an arthropod-borne virus that infects several species of animals and humans mostly in South America. Despite being described as a human pathogen over 60 years ago, little progress has been made towards the ecological and pathological aspects of this pathogen. However, with recent viral spread northward reaching Haiti and Cuba, it has been receiving more attention, evidenced by the growing number of relevant research articles. This commentary article provides the summary of the potential natural reservoirs and the expansion of endemic regions within the context of One Health. The clinical aspects of the human infection are revisited and discussed based on the latest evidence. The article briefly review research on the molecular virology and the pathology, highlighting unanswered questions crucial for comprehensive understanding of this viral disease, which imposes a significant burden on the affected populations.

The multitaskers of the brain: Glial responses to viral infections and associated post-infectious neurologic sequelae

Many viral infections cause acute and chronic neurologic diseases which can lead to degeneration of cortical functions. While neurotropic viruses that gain access to the central nervous system (CNS) may induce brain injury directly via infection of neurons or their supporting cells, they also alter brain function via indirect neuroimmune mechanisms that may disrupt the blood-brain barrier (BBB), eliminate synapses, and generate neurotoxic astrocytes and microglia that prevent recovery of neuronal circuits. Non-neuroinvasive, neurovirulent viruses may also trigger aberrant responses in glial cells, including those that interfere with motor and sensory behaviors, encoding of memories and executive function. Increasing evidence from human and animal studies indicate that neuroprotective antiviral responses that amplify levels of innate immune molecules dysregulate normal neuroimmune processes, even in the absence of neuroinvasion, which may persist after virus is cleared. In this review, we discuss how select emerging and re-emerging RNA viruses induce neuroimmunologic responses that lead to dysfunction of higher order processes including visuospatial recognition, learning and memory, and motor control. Identifying therapeutic targets that return the neuroimmune system to homeostasis is critical for preventing virus-induced neurodegenerative disorders.

Modulation of HERV Expression by Four Different Encephalitic Arboviruses during Infection of Human Primary Astrocytes

Human retroelements (HERVs) are retroviral origin sequences fixed in the human genome. HERVs induction is associated with neurogenesis, cellular development, immune activation, and neurological disorders. Arboviruses are often associated with the development of encephalitis. The interplay between these viruses and HERVs has not been fully elucidated. In this work, we analyzed RNAseq data derived from infected human primary astrocytes by Zika (ZikV), Mayaro (MayV), Oropouche (OroV) and Chikungunya (ChikV) viruses, and evaluated the modulation of HERVs and their nearby genes. Our data show common HERVs expression modulation by both alphaviruses, suggesting conserved evolutionary routes of transcription regulation. A total of 15 HERVs were co-modulated by the four arboviruses, including the highly upregulated HERV4_4q22. Data on the upregulation of genes nearby to these elements in ChikV, MayV and OroV infections were also obtained, and interaction networks were built. The upregulation of 14 genes common among all viruses was observed in the networks, and 93 genes between MayV and ChikV. These genes are related to cellular processes such as cellular replication, cytoskeleton, cell vesicle traffic and antiviral response. Together, our results support the role of HERVs induction in the transcription regulation process of genes during arboviral infections.

A Review of Omics Studies on Arboviruses: Alphavirus, Orthobunyavirus and Phlebovirus

Since the intricate and complex steps in pathogenesis and host-viral interactions of arthropod-borne viruses or arboviruses are not completely understood, the multi-omics approaches, which encompass proteomics, transcriptomics, genomics and metabolomics network analysis, are of great importance. We have reviewed the omics studies on mosquito-borne viruses of the Togaviridae, Peribuyaviridae and Phenuiviridae families, specifically for Chikungunya, Mayaro, Oropouche and Rift Valley Fever viruses. Omics studies can potentially provide a new perspective on the pathophysiology of arboviruses, contributing to a better comprehension of these diseases and their effects and, hence, provide novel insights for the development of new antiviral drugs or therapies.