Immunogenetic landscape of COVID-19 infections related neurological complications

The human leukocyte antigen (HLA) is a critical component of antigen presentation and plays crucial role in conferring differential susceptibility and severity of diseases caused by viruses such as COVID-19. The immunogenetic profile of populations, BCG vaccination status, and a host of lifestyle factors might contribute to the observed variations in mortality rates due to COVID-19. These genetic, epigenetic, and environmental factors could widely influence infection dynamics and immune responses against COVID-19. The aim of this review is to provide an update on HLA association with SARS-CoV-2 infection in global populations and to highlight the possible neurological involvements. We also set out to explore the HLA immunogenetic markers related to COVID‐19 infections that can be used in screening high‐risk individuals for personalized therapies and in community-based vaccine development. © 2023 Elsevier Inc. All rights reserved.

Review of Neurological Manifestations of SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect any part of the neuraxis. Many neurological conditions have been attributed to be caused by SARS-CoV-2, namely encephalopathy (acute necrotizing encephalopathy and encephalopathy with reversible splenial lesions), seizures, stroke, cranial nerve palsies, meningoencephalitis, acute disseminated encephalomyelitis (ADEM), transverse myelitis (long and short segment), Guillain-Barré syndrome (GBS) and its variants, polyneuritis cranialis, optic neuritis (ON), plexopathy, myasthenia gravis (MG), and myositis. The pathophysiology differs depending on the time frame of presentation. In patients with concomitant pulmonary disease, for instance, acute neurological illness appears to be caused by endotheliopathy and cytokine storm. Autoimmunity and molecular mimicry are causative for post-coronavirus disease 2019 (COVID-19)-sequelae. It has not yet been shown that the virus can penetrate the central nervous system (CNS) directly. This review aims to describe the disease and root pathogenic cause of the various neurological manifestations of COVID-19. We searched Pubmed/Medline and Google Scholar using the keywords "SARS-CoV-2" and "neurological illness" for articles published between January 2020 and November 2022. Then, we used the SWIFT-Review (Sciome LLC, North Carolina, United States), a text-mining workbench for systematic review, to classify the 1383 articles into MeSH hierarchical tree codes for articles on various parts of the nervous system, such as the CNS, peripheral nervous system, autonomic nervous system, neuromuscular junction, sensory system, and musculoskeletal system. Finally, we reviewed 152 articles in full text. SARS-CoV-2 RNA has been found in multiple brain areas without any histopathological changes. Despite the absence of in vivo virions or virus-infected cells, CNS inflammation has been reported, especially in the olfactory bulb and brain stem. SARS-CoV-2 genomes and proteins have been found in affected individuals' brain tissues, but corresponding neuropathologic changes are seldom found in these cases. Additionally, viral RNA can rarely be identified in neurological patients' CSF post hoc SARS-CoV-2 infection. Most patients with neurological symptoms do not have active viral replication in the nervous system and infrequently have typical clinical and laboratory characteristics of viral CNS infections. Endotheliopathy and the systemic inflammatory response to SARS-CoV-2 infection play a crucial role in developing neuro-COVID-19, with proinflammatory cytokine release mediating both pathological pathways. The systemic inflammatory mediators likely activate astrocytes and microglia across the blood-brain barrier, indirectly affecting CNS-specific immune activation and tissue injury. The management differs according to co-morbidities and the neurological disorder.

iPSC-derived three-dimensional brain organoid models and neurotropic viral infections.

Progress in stem cell research has revolutionized the medical field for more than two decades. More recently, the discovery of induced pluripotent stem cells (iPSCs) has allowed for the development of advanced disease modeling and tissue engineering platforms. iPSCs are generated from adult somatic cells by reprogramming them into an embryonic-like state via the expression of transcription factors required for establishing pluripotency. In the context of the central nervous system (CNS), iPSCs have the potential to differentiate into a wide variety of brain cell types including neurons, astrocytes, microglial cells, endothelial cells, and oligodendrocytes. iPSCs can be used to generate brain organoids by using a constructive approach in three-dimensional (3D) culture in vitro. Recent advances in 3D brain organoid modeling have provided access to a better understanding of cell-to-cell interactions in disease progression, particularly with neurotropic viral infections. Neurotropic viral infections have been difficult to study in two-dimensional culture systems in vitro due to the lack of a multicellular composition of CNS cell networks. In recent years, 3D brain organoids have been preferred for modeling neurotropic viral diseases and have provided invaluable information for better understanding the molecular regulation of viral infection and cellular responses. Here we provide a comprehensive review of the literature on recent advances in iPSC-derived 3D brain organoid culturing and their utilization in modeling major neurotropic viral infections including HIV-1, HSV-1, JCV, ZIKV, CMV, and SARS-CoV2.

RVG Peptide-Functionalized Favipiravir Nanoparticle Delivery System Facilitates Antiviral Therapy of Neurotropic Virus Infection in a Mouse Model.

Neurotropic viruses severely damage the central nervous system (CNS) and human health. Common neurotropic viruses include rabies virus (RABV), Zika virus, and poliovirus. When treating neurotropic virus infection, obstruction of the blood-brain barrier (BBB) reduces the efficiency of drug delivery to the CNS. An efficient intracerebral delivery system can significantly increase intracerebral delivery efficiency and facilitate antiviral therapy. In this study, a rabies virus glycopeptide (RVG) functionalized mesoporous silica nanoparticle (MSN) packaging favipiravir (T-705) was developed to generate T-705@MSN-RVG. It was further evaluated for drug delivery and antiviral treatment in a VSV-infected mouse model. The RVG, a polypeptide consisting of 29 amino acids, was conjugated on the nanoparticle to enhance CNS delivery. The T-705@MSN-RVG caused a significant decrease in virus titers and virus proliferation without inducing substantial cell damage in vitro. By releasing T-705, the nanoparticle promoted viral inhibition in the brain during infection. At 21 days post-infection (dpi), a significantly enhanced survival ratio (77%) was observed in the group inoculated with nanoparticle compared with the non-treated group (23%). The viral RNA levels were also decreased in the therapy group at 4 and 6 dpi compared with that of the control group. The T-705@MSN-RVG could be considered a promising system for CNS delivery for treating neurotropic virus infection.

SARS-CoV-2 neurotropism and other possible causes of olfactory disorders in COVID-19.

Coronavirus disease 2019 (COVID-19) is an acute infectious respiratory disease (AIRD) caused by infection with the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first cases were diagnosed and reported in Wuhan, central China, in November 2019. The disease initially occurred locally. However, the number of infected individuals increased dynamically and spread worldwide. The most common symptoms of the SARS-CoV-2 infection include malaise, fever, dry cough and dyspnoea. Over time, reports of new COVID-19 symptoms included taste and smell disorders. A potential cause of these disorders is related to neurotropism, i.e. the affinity of SARS-CoV-2 to the nervous system. Angiotensin-converting enzyme 2 receptor is essential in the pathogenesis of SARS-CoV-2 infection. The receptor is found in many tissues and organs, including the olfactory epithelium, neurons and neuroglial cells. Another potential cause is neuroinvasiveness, i.e. the ability of the virus to invade the central nervous system, and thereby damage its structures. As a result, olfactory disorders may occur. Other concepts, such as the inflammatory response of the body and the concept of stroke or damage to olfactory supporting cells, are also considered.

Mucosal plasma cells are required to protect the upper airway and brain from infection.

While blood antibodies mediate protective immunity in most organs, whether they protect nasal surfaces in the upper airway is unclear. Using multiple viral infection models in mice, we found that blood-borne antibodies could not defend the olfactory epithelium. Despite high serum antibody titers, pathogens infected nasal turbinates, and neurotropic microbes invaded the brain. Using passive antibody transfers and parabiosis, we identified a restrictive blood-endothelial barrier that excluded circulating antibodies from the olfactory mucosa. Plasma cell depletions demonstrated that plasma cells must reside within olfactory tissue to achieve sterilizing immunity. Antibody blockade and genetically deficient models revealed that this local immunity required CD4+ T cells and CXCR3. Many vaccine adjuvants failed to generate olfactory plasma cells, but mucosal immunizations established humoral protection of the olfactory surface. Our identification of a blood-olfactory barrier and the requirement for tissue-derived antibody has implications for vaccinology, respiratory and CNS pathogen transmission, and B cell fate decisions.

Exogenous Players in Mitochondria-Related CNS Disorders: Viral Pathogens and Unbalanced Microbiota in the Gut-Brain Axis.

Billions of years of co-evolution has made mitochondria central to the eukaryotic cell and organism life playing the role of cellular power plants, as indeed they are involved in most, if not all, important regulatory pathways. Neurological disorders depending on impaired mitochondrial function or homeostasis can be caused by the misregulation of "endogenous players", such as nuclear or cytoplasmic regulators, which have been treated elsewhere. In this review, we focus on how exogenous agents, i.e., viral pathogens, or unbalanced microbiota in the gut-brain axis can also endanger mitochondrial dynamics in the central nervous system (CNS). Neurotropic viruses such as Herpes, Rabies, West-Nile, and Polioviruses seem to hijack neuronal transport networks, commandeering the proteins that mitochondria typically use to move along neurites. However, several neurological complications are also associated to infections by pandemic viruses, such as Influenza A virus and SARS-CoV-2 coronavirus, representing a relevant risk associated to seasonal flu, coronavirus disease-19 (COVID-19) and "Long-COVID". Emerging evidence is depicting the gut microbiota as a source of signals, transmitted via sensory neurons innervating the gut, able to influence brain structure and function, including cognitive functions. Therefore, the direct connection between intestinal microbiota and mitochondrial functions might concur with the onset, progression, and severity of CNS diseases.

Using 2D and 3D pluripotent stem cell models to study neurotropic viruses.

Understanding the impact of viral pathogens on the human central nervous system (CNS) has been challenging due to the lack of viable human CNS models for controlled experiments to determine the causal factors underlying pathogenesis. Human embryonic stem cells (ESCs) and, more recently, cellular reprogramming of adult somatic cells to generate human induced pluripotent stem cells (iPSCs) provide opportunities for directed differentiation to neural cells that can be used to evaluate the impact of known and emerging viruses on neural cell types. Pluripotent stem cells (PSCs) can be induced to neural lineages in either two- (2D) or three-dimensional (3D) cultures, each bearing distinct advantages and limitations for modeling viral pathogenesis and evaluating effective therapeutics. Here we review the current state of technology in stem cell-based modeling of the CNS and how these models can be used to determine viral tropism and identify cellular phenotypes to investigate virus-host interactions and facilitate drug screening. We focus on several viruses (e.g., human immunodeficiency virus (HIV), herpes simplex virus (HSV), Zika virus (ZIKV), human cytomegalovirus (HCMV), SARS-CoV-2, West Nile virus (WNV)) to illustrate key advantages, as well as challenges, of PSC-based models. We also discuss how human PSC-based models can be used to evaluate the safety and efficacy of therapeutic drugs by generating data that are complementary to existing preclinical models. Ultimately, these efforts could facilitate the movement towards personalized medicine and provide patients and physicians with an additional source of information to consider when evaluating available treatment strategies.

The relationship between Parkinson's disease and Coronavirus 2019 (COVID-19)

Background: The main trigger for Parkinson's disease is a mutated version of a protein called alpha-synuclein.This protein accumulates in dopamine-producing neurons. COVID-19 can increase the risk of Parkinson's and other neurological diseases. Methods:This review study was conducted by the library method. Results: The results showed that the virus can cause neuroinflammation, which, as a predisposing event, predisposes the brain to overreaction to subsequent neurological events. This secondary neurological event can be anything from another viral infection to poisoning and even aging. A secondary neurological event triggers an abnormal brain response that leads to nerve degeneration and eventually Parkinson's disease. The results show that the SARS-CoV-2 virus as a neurotropic virus can enter brain tissue. Conclusion: Therefore, the virus certainly has the potential to act as a predisposing event in increasing the risk of Parkinson's disease.

Neuroprotective Drug Discovery From Phytochemicals and Metabolites for CNS Viral Infection: A Systems Biology Approach With Clinical and Imaging Validation.

Background: Recent studies have reported that pulmo-neurotropic viruses can cause systemic invasion leading to acute respiratory failure and neuroinfection. The tetracycline class of secondary metabolites of microorganisms is effective against several migrating neurotropic viral disorders, as Japanese-Encephalitis (JE), Severe-Acute-Respiratory-Syndrome Coronavirus-2 (SARS-COV2), Human-Immunodeficiency-Virus (HIV), and Simian-Immunodeficiency-Virus (SIV). Another microbial secondary metabolite, cephalosporin, can be used for anti-viral combination therapy. However, a substantial public health debacle is viral resistance to such antibiotics, and, thus, one needs to explore the antiviral efficiency of other secondary metabolites, as phytochemicals. Hence, here, we investigate phytochemicals like podophyllotoxin, chlorogenic acid, naringenin, and quercetin for therapeutic efficiency in neurotropic viral infections. Methods: To investigate the possibility of the afferent neural pathway of migrating virus in man, MRI scanning was performed on human subjects, whereby the connections between cranial nerves and the brain-stem/limbic-region were assessed by fiber-tractography. Moreover, human clinical-trial assessment (n = 140, p = 0.028) was done for formulating a quantitative model of antiviral pharmacological intervention. Furthermore, docking studies were performed to identify the binding affinity of phytochemicals toward antiviral targets as (i) host receptor [Angiotensin-converting Enzyme-2], (ii) main protease of SARS-COV2 virus (iii) NS3-Helicase/Nucleoside triphosphatase of Japanese-encephalitis-virus, and the affinities were compared to standard tetracycline and cephalosporin antibiotics. Then, network pharmacology analysis was utilized to identify the possible mechanism of action of those phytochemicals. Results: Human MRI-tractography analysis showed fiber connectivity, as: (a) Path-1: From the olfactory nerve to the limbic region (2) Path-2: From the peripheral glossopharyngeal nerve and vagus nerves to the midbrain-respiratory-center. Docking studies revealed comparable binding affinity of phytochemicals, tetracycline, and cephalosporin antibiotics toward both (a) virus receptors, (b) host cell receptors where virus-receptor binds. The phytochemicals effectively countered the cytokine storm-induced neuroinflammation, a critical pathogenic pathway. We also found that a systems-biology-based double-hit mathematical bi-exponential model accounts for patient survival-curve under antiviral treatment, thus furnishing a quantitative-clinical framework of secondary metabolite action on virus and host cells. Conclusion: Due to the current viral resistance to antibiotics, we identified novel phytochemicals that can have clinical therapeutic application to neurotropic virus infection. Based on human MRI scanning and clinical-trial analysis, we demarcated the anatomical pathway and systems-biology-based quantitative formulation of the mechanism of antiviral action.

COVID-19 AS A CAUSE OF COMA IN ADULT ONSET VANISHING WHITE MATTER DISEASE

A 34 year old female presented with fever, diarrhoea, confusion, and a decline in mobility, having recently tested positive for COVID-19. Her medical history included patent foramen ovale, primary ovarian failure and leukoencephalopathy which had been investigated in her 20s leading to a clinical diagnosis of Vanishing White Matter disease (VWM). On admission she deteriorated rapidly with decreased GCS requiring frequent critical care review. MRI demonstrated mild progression of the cerebral atrophy and slight increase in the 'cystic' changes in the white matter. Lumbar puncture was unremarkable. EEG demonstrated widespread cerebral dysfunction with frontotemporal emphasis but without seizure activity. She was managed with supportive care recovering to her baseline function within days. VWM is a leukodystrophy caused by recessive mutations in eukaryotic initiation factor 2B (eIF2b) complex. Adult onset presentations have been described which have a slowly progressive course. Patients with VWM are known to rapidly decline with fever, and mild head injury occasionally resulting in coma. Our case high-lights the potentially devastating effects of a neurotropic virus such as COVID-19 in VWM, and the need to consider rare genetic disorders in adult patients presenting with extensive white matter abnormalities on MRI and premature ovarian failure.

Persistent COVID-19 and chronic pain. Are we prepared?: Presentation of three clinical cases and review of the literature

Long COVID is a term that describes a group of multiorganic symptoms that affect patients who have suffered from COVID-19 and who remain symptomatic for a sustained period of time after the acute phase of the disease. Amongst those symptoms, pain is one of the most frequently reported, shaping into different specific syndromes such as persistent thoracic pain, generalized pain, arthralgia, myalgia and cephalalgia. Multiple mechanisms can explain the onset and perpetuation of chronic pain in these patients. It is known that SARS-CoV-2 is a neurotropic virus that can alter the somatosensory nervous system and which can also cause an intense autoimmune response with effects on multiple organs and systems. We present three clinical cases of long COVID where pain was the main symptom altogether with anxiety, depression, insomnia, catastrophic thoughts related to pain, cognitive impairment and post-traumatic stress disorder. These all show the existing complexity in the management of this new-found entity. Given the extensive number of SARS-CoV-2 infections reported globally, chronic pain in relation to long COVID can become a public health issue. Therefore, it is necessary to make it visible and to establish strategies to prevent it and confront it.

A Case Report of Herpes Zoster Ophthalmicus and Meningitis After COVID-19 Vaccination.

There are several reports that herpes zoster characterized by reactivation of varicella zoster virus (VZV) following coronavirus disease 2019 (COVID-19) vaccines can occur. Herein, we report VZV meningitis, herpes zoster ophthalmicus (HZO), and late neurotrophic keratitis after receiving a second dose of messenger RNA (mRNA) COVID-19 vaccine. A 74-year-old man developed a vesicular skin rash on the forehead, scalp, nose, and left upper eyelid with a severe headache. Five days earlier, he received a second dose of the BNT162b2 mRNA vaccine on his left arm. Ocular examination revealed conjunctival hyperemia and pseudodendrite in the peripheral cornea. VZV was detected in the cerebrospinal fluid using polymerase chain reaction. The patient was diagnosed with HZO and meningitis. The patient was treated with intravenous acyclovir and topical acyclovir ointment and levofloxacin 1.5% eye drops. One month later, he developed a central epithelial defect with a rolled margin, typical of a neurotrophic ulcer. Treatment with a therapeutic contact lens and a combination of topical recombinant human epithelial growth factor and ofloxacin ointment was initiated. At six months after vaccination, the slit-lamp examination findings were stable with a mild corneal superficial stromal haze.

Applications of Brain Organoids for Infectious Diseases.

Brain organoids are self-organized three-dimensional aggregates generated from pluripotent stem cells. They exhibit complex cell diversities and organized architectures that resemble human brain development ranging from neural tube formation, neuroepithelium differentiation, neurogenesis and gliogenesis, to neural circuit formation. Rapid advancements in brain organoid culture technologies have allowed researchers to generate more accurate models of human brain development and neurological diseases. These models also allow for direct investigation of pathological processes associated with infectious diseases affecting the nervous system. In this review, we first briefly summarize recent advancements in brain organoid methodologies and neurodevelopmental processes that can be effectively modeled by brain organoids. We then focus on applications of brain organoids to investigate the pathogenesis of neurotropic viral infection. Finally, we discuss limitations of the current brain organoid methodologies as well as applications of other organ specific organoids in the infectious disease research.

[The use of neurotropic therapy in young patients with postcovid syndrome]. / Primenenie neirotropnoi terapii u molodykh patsientov s postkovidnym sindromom.

OBJECTIVE: The aim of the present study was to identify postcovid asthenic syndrome and cognitive disorders in young patients on an outpatient basis, and to evaluate the experience of using combined neurotropic therapy in this category of patients. MATERIAL AND METHODS: Included 87 young patients who underwent COVID-19 and applied for an outpatient appointment with a neurologist. All patients underwent a scale assessment of the severity of asthenia on the MFI-20 scale, cognitive functions - on the MMSE scale, the 5-word test and the Schulte test. The severity of the anxiety syndrome - according to the Spielberger Anxiety Scale. All patients in the study group were treated with a combination of Cortexin and Recognan, and a repeat study was conducted 4 weeks after treatment. RESULTS: The study revealed the predominance in the observation group of patients with a comorbid background, as well as pronounced anxiety disorders. After the complex treatment, there was a significant decrease in the indicators of common, physical, mental asthenia, as well as an increase in motivational activity, there was a decrease in situational anxiety, and to a lesser extent personal anxiety. According to cognitive tests, there was an improvement in indicators on the MMSE scale, direct reproduction of the 5-word test, significant changes in the evaluation of work efficiency when performing the Schulte test. CONCLUSION: It should be noted that the positive results of this study can be considered a decrease in the severity and severity of asthenia symptoms, a decrease in anxiety manifestations, and an improvement in cognitive functions against the background of complex neurotropic therapy with Cortexin and Recognan. Preference in this situation should be given to drugs with a multimodal mechanism of action, as well as creating optimal combinations of drugs that potentiate each other's action.

[Some psychiatric and neurological aspects of the asymptomatic and mild course of COVID-19]. / Nekotorye psikhiatricheskie i nevrologicheskie aspekty bessimptomnogo i legkogo techeniya COVID-19.

OBJECTIVE: To study neurological and mental disorders associated with the inapparent and mild course of COVID-19. MATERIAL AND METHODS: The study included 50 patients (mean age 35.2±11.4 years) admitted to a psychiatric hospital due to depressive spectrum disorders. Patients were divided into two groups: patients (n=16) who had IgG antibodies to SARS-CoV-2 (main group) and patients (n=34) without a history of COVID-19 (comparison group). RESULTS AND CONCLUSION: Patients of the main group showed a difference in the structure of asthenic disorders compared with the comparison group. Also, there was a significant predominance of the severity of asthenic symptoms and anxiety in the structure of psychopathological disorders in depressive spectrum disorders. The viral intoxication contributes to the formation of a kind of asthenic «soil¼ (with characteristic manifestations). In the future, in the case of the development of any stress-associated disorder, more pronounced psychopathological disorders are noted compared with patients of the comparison group. The authors describe a variant of the course of COVID-19, in which the development of ischemic stroke was the first clinical manifestation of the disease. These disorders are based on the pronounced neurotropic effect of SARS-CoV-2 and its effect on the neurovascular unit.

Functionalized Nanoparticles in Prevention and Targeted Therapy of Viral Diseases With Neurotropism Properties, Special Insight on COVID-19.

Neurotropic viruses have neural-invasive and neurovirulent properties to damage the central nervous system (CNS), leading to humans' fatal symptoms. Neurotropic viruses comprise a lot of viruses, such as Zika virus (ZIKV), herpes simplex virus (HSV), rabies virus (RABV), and severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Effective therapy is needed to prevent infection by these viruses in vivo and in vitro. However, the blood-brain barrier (BBB) usually prevents macromolecules from entering the CNS, which challenges the usage of the traditional probes, antiviral drugs, or neutralizing antibodies in the CNS. Functionalized nanoparticles (NPs) have been increasingly reported in the targeted therapy of neurotropic viruses due to their sensitivity and targeting characteristics. Therefore, the present review outlines efficient functionalized NPs to further understand the recent trends, challenges, and prospects of these materials.

Occurrence of Guillain-Barre Syndrome During the Initial Symptomatic Phase of COVID-19 Disease: Coincidence or Consequence?

Viral infections are frequently present before the clinical manifestation of Guillain-Barre syndrome (GBS). Multiple studies on coronaviruses have shown that these viruses have neurotropic characteristics, and their molecular mimicry can induce inflammatory demyelinating neuropathy. Herein, we describe a case of a GBS in an 85-year-old patient infected with SARS-CoV-2, manifested with acute progressive symmetric ascending quadriparesis, urinary dysautonomia, and dysphagia, who responded well to treatment with intravenous human immunoglobulin.

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

Oropouche virus (OROV) is an emerging arbovirus in South and Central Americas with high spreading potential. OROV infection has been associated with neurological complications and OROV genomic RNA has been detected in cerebrospinal fluid from patients, suggesting its neuroinvasive potential. Motivated by these findings, neurotropism and neuropathogenesis of OROV have been investigated in vivo in murine models, which do not fully recapitulate the complexity of the human brain. Here we have used slice cultures from adult human brains to investigate whether OROV is capable of infecting mature human neural cells in a context of preserved neural connections and brain cytoarchitecture. Our results demonstrate that human neural cells can be infected ex vivo by OROV and support the production of infectious viral particles. Moreover, OROV infection led to the release of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) and diminished cell viability 48 h post-infection, indicating that OROV triggers an inflammatory response and tissue damage. Although OROV-positive neurons were observed, microglia were the most abundant central nervous system (CNS) cell type infected by OROV, suggesting that they play an important role in the response to CNS infection by OROV in the adult human brain. Importantly, we found no OROV-infected astrocytes. To the best of our knowledge, this is the first direct demonstration of OROV infection in human brain cells. Combined with previous data from murine models and case reports of OROV genome detection in cerebrospinal fluid from patients, our data shed light on OROV neuropathogenesis and help raising awareness about acute and possibly chronic consequences of OROV infection in the human brain.

The Influence of Virus Infection on Microglia and Accelerated Brain Aging.

Microglia are the resident immune cells of the central nervous system contributing substantially to health and disease. There is increasing evidence that inflammatory microglia may induce or accelerate brain aging, by interfering with physiological repair and remodeling processes. Many viral infections affect the brain and interfere with microglia functions, including human immune deficiency virus, flaviviruses, SARS-CoV-2, influenza, and human herpes viruses. Especially chronic viral infections causing low-grade neuroinflammation may contribute to brain aging. This review elucidates the potential role of various neurotropic viruses in microglia-driven neurocognitive deficiencies and possibly accelerated brain aging.