Borna disease virus and human disease

Viral infections in etiology of mental disorders: a broad analysis of cytokine profile similarities - a narrative review

The recent pandemic caused by the SARS-CoV-2 virus and the associated mental health complications have renewed scholarly interest in the relationship between viral infections and the development of mental illnesses, a topic that was extensively discussed in the previous century in the context of other viruses, such as influenza. The most probable and analyzable mechanism through which viruses influence the onset of mental illnesses is the inflammation they provoke. Both infections and mental illnesses share a common characteristic: an imbalance in inflammatory factors. In this study, we sought to analyze and compare cytokine profiles in individuals infected with viruses and those suffering from mental illnesses. The objective was to determine whether specific viral diseases can increase the risk of specific mental disorders and whether this risk can be predicted based on the cytokine profile of the viral disease. To this end, we reviewed existing literature, constructed cytokine profiles for various mental and viral diseases, and conducted comparative analyses. The collected data indicate that the risk of developing a specific mental illness cannot be determined solely based on cytokine profiles. However, it was observed that the combination of IL-8 and IL-10 is frequently associated with psychotic symptoms. Therefore, to assess the risk of mental disorders in infected patients, it is imperative to consider the type of virus, the mental complications commonly associated with it, the predominant cytokines to evaluate the risk of psychotic symptoms, and additional patient-specific risk factors.

Exploiting hosts and vectors: viral strategies for facilitating transmission

Viruses have developed various strategies to ensure their survival and transmission. One intriguing strategy involves manipulating the behavior of infected arthropod vectors and hosts. Through intricate interactions, viruses can modify vector behavior, aiding in crossing barriers and improving transmission to new hosts. This manipulation may include altering vector feeding preferences, thus promoting virus transmission to susceptible individuals. In addition, viruses employ diverse dissemination methods, including cell-to-cell and intercellular transmission via extracellular vesicles. These strategies allow viruses to establish themselves in favorable environments, optimize replication, and increase the likelihood of spreading to other individuals. Understanding these complex viral strategies offers valuable insights into their biology, transmission dynamics, and potential interventions for controlling infections. Unraveling interactions between viruses, hosts, and vectors enables the development of targeted approaches to effectively mitigate viral diseases and prevent transmission.

Alzheimer's disease as a viral disease: Revisiting the infectious hypothesis

Alzheimer's disease (AD) represents the most frequent type of dementia in elderly people. Two major forms of the disease exist: sporadic - the causes of which have not yet been fully understood - and familial - inherited within families from generation to generation, with a clear autosomal dominant transmission of mutations in Presenilin 1 (PSEN1), 2 (PSEN2) or Amyloid Precursors Protein (APP) genes. The main hallmark of AD consists of extracellular deposits of amyloid-beta (Aβ) peptide and intracellular deposits of the hyperphosphorylated form of the tau protein. An ever-growing body of research supports the viral infectious hypothesis of sporadic forms of AD. In particular, it has been shown that several herpes viruses (i.e., HHV-1, HHV-2, HHV-3 or varicella zoster virus, HHV-4 or Epstein Barr virus, HHV-5 or cytomegalovirus, HHV-6A and B, HHV-7), flaviviruses (i.e., Zika virus, Dengue fever virus, Japanese encephalitis virus) as well as Human Immunodeficiency Virus (HIV), hepatitis viruses (HAV, HBV, HCV, HDV, HEV), SARS-CoV2, Ljungan virus (LV), Influenza A virus and Borna disease virus, could increase the risk of AD. Here, we summarized and discussed these results. Based on these findings, significant issues for future studies are also put forward.

Increasing Evidence of Human Infections by the Neurotropic Borna Disease Virus 1 (BoDV-1)

Due to relatively rare instances of human infections by the Borna disease virus 1 (BoDV-1) and the difficulty of developing and validating a test for diagnosing it, human cases of fatal encephalitis caused by BoDV-1 have been difficult to confirm. Zoonotic transmissions of BoDV-1 have also been suspected but have not been definitively ascertained. Using serum and cerebrospinal fluid of at-risk patients, who were living in northern and eastern parts of Germany, the authors of a recent study¹ successfully developed and validated a new workflow for rapid testing of BoDV-1 infections in humans. Using next-generation sequencing method, they were able to recover the full-length BoDV-1 genome from the patient's brain tissue that phylogenetically match the viral sequences to BoDV-1 strains found in shrews and domesticated animals, implicating zoonotic transmissions of this virus. This editorial aims to raise awareness about this emerging neurotropic virus that might have important public health implications.

Interactions of Equine Viruses with the Host Kinase Machinery and Implications for One Health and Human Disease

Zoonotic pathogens that are vector-transmitted have and continue to contribute to several emerging infections globally. In recent years, spillover events of such zoonotic pathogens have increased in frequency as a result of direct contact with livestock, wildlife, and urbanization, forcing animals from their natural habitats. Equines serve as reservoir hosts for vector-transmitted zoonotic viruses that are also capable of infecting humans and causing disease. From a One Health perspective, equine viruses, therefore, pose major concerns for periodic outbreaks globally. Several equine viruses have spread out of their indigenous regions, such as West Nile virus (WNV) and equine encephalitis viruses (EEVs), making them of paramount concern to public health. Viruses have evolved many mechanisms to support the establishment of productive infection and to avoid host defense mechanisms, including promoting or decreasing inflammatory responses and regulating host machinery for protein synthesis. Viral interactions with the host enzymatic machinery, specifically kinases, can support the viral infectious process and downplay innate immune mechanisms, cumulatively leading to a more severe course of the disease. In this review, we will focus on how select equine viruses interact with host kinases to support viral multiplication.

Back to the Future: The Role of Infections in Psychopathology. Focus on OCD

OBJECTIVE

Recently, there has been a resurgence of interest in the relationship between infections and psychopathology, given the increasing data on the neurotropism and neurological/psychiatric morbidity of the SARS-COV2 virus, responsible for the current worldwide pandemic. Although the majority of observations were those obtained in mood and schizophrenic disorders, a few data are also available on the presence of bacterial or viral infections in patients suffering from obsessive-compulsive disorder (OCD). Therefore, given the limited information, the present paper aimed at reviewing the most updated evidence of infections in neuropsychiatric disorders and their possible mechanisms of actions, with a narrow focus on microbes in OCD.

METHOD

This paper is a narrative review. The databases of PubMed, Scopus, Embase, PsycINFO and Google Scholar were accessed to research and collect English language papers published between 1 January 1980 and 31 December 2021. The data on PANDAS/PANS and those observed during severe brain infections were excluded.

RESULTS

Several pathogens have been associated with an increased risk to develop a broad spectrum of neuropsychiatric conditions, such as schizophrenia, mood disorders, autism, attention-deficit/hyperactivity disorder, anorexia nervosa, and post-traumatic stress disorder. Some evidence supported a possible role of infections also in the pathophysiology of OCD. Infections from Herpes simplex virus 1, Borna disease virus, Group A-Beta Hemolytic Streptococcus, Borrelia spp., and Toxoplasma gondii were actually found in patients with OCD. Although different mechanisms have been hypothesized, all would converge to trigger functional/structural alterations of specific circuits or immune processes, with cascade dysfunctions of several other systems.

CONCLUSIONS

Based on the current evidence, a possible contribution of different types of microbes has been proposed for different neuropsychiatric disorders including OCD. However, the currently available literature is meager and heterogeneous in terms of sample characteristics and methods used. Therefore, further studies are needed to better understand the impact of infectious agents in neuropsychiatric disorders. Our opinion is that deeper insights in this field might contribute to a better definition of biological underpinnings of specific clinical pictures, as well as to promote psychiatric precision medicine, with treatments based on altered pathological pathways of single patients. This might be particularly relevant in OCD, a disorder with a high proportion of patients who are resistant or do not respond to conventional therapeutic strategies.

Development of a nonhuman primate model for mammalian bornavirus infection

Until recently, it was assumed that members of the family Bornaviridae could not induce severe disease in humans. Today, however, Borna disease virus 1 (BoDV-1), as well as the more recently emerged variegated squirrel bornavirus 1 (VSBV-1), are known as causative agents of lethal encephalitis in humans. In order to establish animal models reflecting the pathogenesis in humans and for countermeasure efficacy testing, we infected twelve rhesus macaques (Macaca mulatta) either with VSBV-1 or with BoDV-1. For each virus, three monkeys each were inoculated with 2 × 10⁴ focus forming units by the intracerebral route or by multiple peripheral routes (intranasal, conjunctival, intramuscular, and subcutaneous; same dose in total). All BoDV-1 and VSBV-1 intracerebrally infected monkeys developed severe neurological signs around 5 to 6 or 8 to 12 weeks postinfection, respectively. Focal myoclonus and tremors were the most prominent observations in BoDV-1 and VSBV-1-infected animals. VSBV-1-infected animals also showed behavioral changes. Only one BoDV-1 peripherally infected animal developed similar disease manifestations. All animals with severe clinical disease showed high viral loads in brain tissues and displayed perivascular mononuclear cuffs with a predominance of lymphocytes and similar meningeal inflammatory infiltrates. In summary, rhesus macaques intracerebrally infected with mammalian bornaviruses develop a human-like disease and may serve as surrogate models for human bornavirus infection.

microRNA-146a-5p, Neurotropic Viral Infection and Prion Disease (PrD)

The human brain and central nervous system (CNS) harbor a select sub-group of potentially pathogenic microRNAs (miRNAs), including a well-characterized NF-kB-sensitive Homo sapiens microRNA hsa-miRNA-146a-5p (miRNA-146a). miRNA-146a is significantly over-expressed in progressive and often lethal viral- and prion-mediated and related neurological syndromes associated with progressive inflammatory neurodegeneration. These include ~18 different viral-induced encephalopathies for which data are available, at least ~10 known prion diseases (PrD) of animals and humans, Alzheimer’s disease (AD) and other sporadic and progressive age-related neurological disorders. Despite the apparent lack of nucleic acids in prions, both DNA- and RNA-containing viruses along with prions significantly induce miRNA-146a in the infected host, but whether this represents part of the host’s adaptive immunity, innate-immune response or a mechanism to enable the invading prion or virus a successful infection is not well understood. Current findings suggest an early and highly interactive role for miRNA-146a: (i) as a major small noncoding RNA (sncRNA) regulator of innate-immune responses and inflammatory signaling in cells of the human brain and CNS; (ii) as a critical component of the complement system and immune-related neurological dysfunction; (iii) as an inducible sncRNA of the brain and CNS that lies at a critical intersection of several important neurobiological adaptive immune response processes with highly interactive associations involving complement factor H (CFH), Toll-like receptor pathways, the innate-immunity, cytokine production, apoptosis and neural cell decline; and (iv) as a potential biomarker for viral infection, TSE and AD and other neurological diseases in both animals and humans. In this report, we review the recent data supporting the idea that miRNA-146a may represent a novel and unique sncRNA-based biomarker for inflammatory neurodegeneration in multiple species. This paper further reviews the current state of knowledge regarding the nature and mechanism of miRNA-146a in viral and prion infection of the human brain and CNS with reference to AD wherever possible.

How accurately can we assess zoonotic risk?

Identifying the animal reservoirs from which zoonotic viruses will likely emerge is central to understanding the determinants of disease emergence. Accordingly, there has been an increase in studies attempting zoonotic “risk assessment.” Herein, we demonstrate that the virological data on which these analyses are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery. Together, these shortcomings suggest that attempts to assess zoonotic risk using available virological data are likely to be inaccurate and largely only identify those host taxa that have been studied most extensively. We suggest that virus surveillance at the human–animal interface may be more productive.

Determining which organisms harbour viruses that could potentially infect humans is of great topical interest. This Essay demonstrates that the data on which such zoonotic risk assessments are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery.

Infections, inflammation, and risk of neuropsychiatric disorders: the neglected role of "co-infection"

Neuropsychiatric disorders (NPDs) have multiple etiological factors, mainly genetic background, environmental conditions and immunological factors. The host immune responses play a pivotal role in various physiological and pathophysiological process. In NPDs, inflammatory immune responses have shown to be involved in diseases severity and treatment outcome. Inflammatory cytokines and chemokines are involved in various neurobiological pathways, such as GABAergic signaling and neurotransmitter synthesis. Infectious agents are among the major amplifier of inflammatory reactions, hence, have an indirect role in the pathogenesis of NPDs. As such, some infections directly affect the central nervous system (CNS) and alter the genes that involved in neurobiological pathways and NPDs. Interestingly, the most of infectious agents that involved in NPDs (e.g., Toxoplasma gondii, cytomegalovirus and herpes simplex virus) is latent (asymptomatic) and co-or-multiple infection of them are common. Nonetheless, the role of co-or-multiple infection in the pathogenesis of NPDs has not deeply investigated. Evidences indicate that co-or-multiple infection synergically augment the level of inflammatory reactions and have more severe outcomes than single infection. Hence, it is plausible that co-or-multiple infections can increase the risk and/or pathogenesis of NPDs. Further understanding about the role of co-or-multiple infections can offer new insights about the etiology, treatment and prevention of NPDs. Likewise, therapy based on anti-infective and anti-inflammatory agents could be a promising therapeutic option as an adjuvant for treatment of NPDs.

From conifers to cognition: Microbes, brain and behavior

A diversity of bacteria, protozoans and viruses ("endozoites") were recently uncovered within healthy tissues including the human brain. By contrast, it was already recognized a century ago that healthy plants tissues contain abundant endogenous microbes ("endophytes"). Taking endophytes as an informative precedent, we overview the nature, prevalence, and role of endozoites in mammalian tissues, centrally focusing on the brain, concluding that endozoites are ubiquitous in diverse tissues. These passengers often remain subclinical, but they are not silent. We address their routes of entry, mechanisms of persistence, tissue specificity, and potential to cause long-term behavioral changes and/or immunosuppression in mammals, where rabies virus is the exemplar. We extend the discussion to Herpesviridae, Coronaviridae, and Toxoplasma, as well as to diverse bacteria and yeasts, and debate the advantages and disadvantages that endozoite infection might afford to the host and to the ecosystem. We provide a clinical perspective in which endozoites are implicated in neurodegenerative disease, anxiety/depression, and schizophrenia. We conclude that endozoites are instrumental in the delicate balance between health and disease, including age-related brain disease, and that endozoites have played an important role in the evolution of brain function and human behavior.

Avian Bornaviral Ganglioneuritis: Current Debates and Unanswered Questions

Avian bornaviral ganglioneuritis, often referred to as parrot wasting disease, is associated with a newly discovered avian virus from the taxonomic family Bornaviridae. Research regarding the pathogenesis and treatment for this disease is ongoing, with implications for understanding other emerging human and nonhuman diseases, as well as the health and ecology of wildlife. At this time, numerous questions remain unanswered regarding the transmission of the disease, best practices for diagnostic sampling and testing, and whether currently used drug therapies are effective or harmful for afflicted birds. The pathogenesis of the disease also remains unclear with many birds showing resistance to the effects of the virus and being able to remain clinically unaffected for years, while other birds succumb to its effects. New research findings regarding avian bornaviral ganglioneuritis are discussed and important as yet unanswered questions are identified.

Targeting histone epigenetics to control viral infections

During the past decades, many studies have significantly broadened our understanding of complex virus-host interactions to control chromatin structure and dynamics.1, 2 However, the role and impact of such modifications during viral infections is not fully revealed. Indeed, this type of regulation is bidirectional between the virus and the host. While viral replication and gene expression are significantly impacted by histone modifications on the viral chromatin,³ studies have shown that some viral pathogens dynamically manipulate cellular epigenetic factors to enhance their own survival and pathogenesis, as well as escape the immune system defense lines.⁴ In this dynamic, histone posttranslational modifications (PTMs) appear to play fundamental roles in the regulation of chromatin structure and recruitment of other factors.⁵ Genuinely, those PTMs play a vital role in lytic infection, latency reinforcement, or, conversely, viral reactivation.⁶ In this chapter, we will examine and review the involvement of histone modifications as well as their potential manipulation to control infections during various viral life cycle stages, highlighting their prospective implications in the clinical management of human immunodeficiency virus (HIV), herpes simplex virus (HSV), human cytomegalovirus (HCMV), hepatitis B and C viruses (HBV and HCV, respectively), Epstein–Barr virus (EBV), and other viral diseases. Targeting histone modifications is critical in setting the treatment of chronic viral infections with both lytic and latent stages (HIV, HCMV, HSV, RSV), virus-induced cancers (HBV, HCV, EBV, KSHV, HPV), and epidemic/emerging viruses (e.g. influenza virus, arboviruses).

What viruses tell us about evolution and immunity: beyond Darwin?

We describe mechanisms of genetic innovation mediated by viruses and related elements that, during evolution, caused major genetic changes beyond what was anticipated by Charles Darwin. Viruses and related elements introduced genetic information and have shaped the genomes and immune systems of all cellular life forms. None of these mechanisms contradict Darwin's theory of evolution but extend it by means of sequence information that has recently become available. Not only do small increments of genetic information contribute to evolution, but also do major events such as infection by viruses or bacteria, which can supply new genetic information to a host by horizontal gene transfer. Thereby, viruses and virus-like elements act as major drivers of evolution.

Evolution of Immune Systems From Viruses and Transposable Elements

Virus-derived sequences and transposable elements constitute a substantial portion of many cellular genomes. Recent insights reveal the intimate evolutionary relationship between these sequences and various cellular immune pathways. At the most basic level, superinfection exclusion may be considered a prototypical virus-mediated immune system that has been described in both prokaryotes and eukaryotes. More complex immune mechanisms fully or partially derived from mobile genetic elements include CRISPR-Cas of prokaryotes and the RAG1/2 system of vertebrates, which provide immunological memory of foreign genetic elements and generate antibody and T cell receptor diversity, respectively. In this review, we summarize the current knowledge on the contribution of mobile genetic elements to the evolution of cellular immune pathways. A picture is emerging in which the various cellular immune systems originate from and are spread by viruses and transposable elements. Immune systems likely evolved from simple superinfection exclusion to highly complex defense strategies.

Distribution of Viral Antigen and Inflammatory Lesions in the Central Nervous System of Cockatiels ( Nymphicus hollandicus) Experimentally Infected with Parrot Bornavirus 2

Neurotropism is a striking characteristic of bornaviruses, including parrot bornavirus 2 (PaBV-2). Our study evaluated the distribution of inflammatory foci and viral nucleoprotein (N) antigen in the brain and spinal cord of 27 cockatiels ( Nymphicus hollandicus) following experimental infection with PaBV-2 by injection into the pectoral muscle. Tissue samples were taken at 12 timepoints between 5 and 114 days post-inoculation (dpi). Each experimental group had approximately 3 cockatiels per group and usually 1 negative control. Immunolabeling was first observed within the ventral horns of the thoracic spinal cord at 20 dpi and in the brain (thalamic nuclei and hindbrain) at 25 dpi. Both inflammation and viral antigen were restricted to the central core of the brain until 40 dpi. The virus then spread quickly at 60 dpi to both gray and white matter of all analyzed sections of the central nervous system (CNS). Encephalitis was most severe in the thalamus and hindbrain, while myelitis was most prominent in the gray matter and equally distributed in the cervical, thoracic, and lumbosacral spinal cord. Our results demonstrate a caudal to rostral spread of virus in the CNS following experimental inoculation of PABV-2 into the pectoral muscle, with the presence of viral antigen and inflammatory lesions first in the spinal cord and progressing to the brain.

Viral Infections and Obesity

PURPOSE OF REVIEW

Obesity is a multifactorial disease that is now endemic throughout most of the world. Although addressing proximate causes of obesity (excess energy intake and reduced energy expenditure) have been longstanding global health priorities, the problem has continued to worsen at the global level.

RECENT FINDINGS

Numerous microbial agents cause obesity in various experimental models-a phenomena known as infectobesity. Several of the same agents alter metabolic function in human cells and are associated with human obesity or metabolic dysfunction in humans. We address the evidence for a role in the genesis of obesity for viral agents in five broad categories: adenoviridae, herpesviridae, phages, transmissible spongiform encephalopathies (slow virus), and other encephalitides and hepatitides. Despite the importance of this topic area, there are many persistent knowledge gaps that need to be resolved. We discuss factors motivating further research and recommend that future infectobesity investigation should be more comprehensive, leveraged, interventional, and patient-centered.

Synaptic Plasticity and Neurological Disorders in Neurotropic Viral Infections

Based on the type of cells or tissues they tend to harbor or attack, many of the viruses are characterized. But, in case of neurotropic viruses, it is not possible to classify them based on their tropism because many of them are not primarily neurotropic. While rabies and poliovirus are considered as strictly neurotropic, other neurotropic viruses involve nervous tissue only secondarily. Since the AIDS pandemic, the interest in neurotropic viral infections has become essential for all clinical neurologists. Although these neurotropic viruses are able to be harbored in or infect the nervous system, not all the neurotropic viruses have been reported to cause disrupted synaptic plasticity and impaired cognitive functions. In this review, we have discussed the neurotropic viruses, which play a major role in altered synaptic plasticity and neurological disorders.

Borna disease virus infection impacts microRNAs associated with nervous system development, cell differentiation, proliferation and apoptosis in the hippocampi of neonatal rats

MicroRNAs (miRNAs) regulate gene expression by inhibiting transcription or translation and are involved in diverse biological processes, including development, cellular differentiation and tumor generation. miRNA microarray technology is a high‑throughput global analysis tool for miRNA expression profiling. Here, the hippocampi of four borna disease virus (BDV)‑infected and four non‑infected control neonatal rats were selected for miRNA microarray and bioinformatic analysis. Reverse transcription quantitative polymerase chain reaction (RT‑qPCR) analysis was subsequently performed to validate the dysregulated miRNAs. Seven miRNAs (miR‑145*, miR‑146a*, miR‑192*, miR‑200b, miR‑223*, miR‑449a and miR‑505), showed increased expression, whereas two miRNAs (miR‑126 and miR‑374) showed decreased expression in the BDV‑infected group. By RT‑qPCR validation, five miRNAs (miR‑126, miR‑200b, miR‑374, miR‑449a and miR‑505) showed significantly decreased expression (P<0.05) in response to BDV infection. Biocarta pathway analysis predicted target genes associated with 'RNA', 'IGF1mTOR', 'EIF2', 'VEGF', 'EIF', 'NTHI', 'extrinsic', 'RB', 'IL1R' and 'IGF1' pathways. Gene Ontology analysis predicted target genes associated with 'peripheral nervous system development', 'regulation of small GTPase-mediated signal transduction', 'regulation of Ras protein signal transduction', 'aerobic respiration', 'membrane fusion', 'positive regulation of cell cycle', 'cellular respiration', 'heterocycle metabolic process', 'protein tetramerization' and 'regulation of Rho protein signal transduction' processes. Among the five dysregulated miRNAs identified by RT‑qPCR, miR‑126, miR‑200b and miR‑449a showed a strong association with nervous system development, cell differentiation, proliferation and apoptosis.

Human but Not Laboratory Borna Disease Virus Inhibits Proliferation and Induces Apoptosis in Human Oligodendrocytes In Vitro

Borna disease virus (BDV) is a neurotropic virus that produces neuropsychiatric dysfunction in a wide range of warm-blooded species. Several studies have associated BDV with human psychiatric illness, but the findings remain controversial. Although oligodendrocytes are a major glial component of brain white matter and play a pivotal role in neuronal cell function, BDV's effects on human oligodendrocytes have not been clarified. Here, the effects of two BDV strains, Hu-H1 (isolated from a bipolar patient) and Strain V (a laboratory strain), on the proliferation and apoptosis of human oligodendrocytes were investigated. Three experimental cell lines were constructed: Hu-H1-infected oligodendroglioma (Hu-H1) cells, Strain V-infected oligodendroglioma (Strain V) cells, and non-infected oligodendroglioma (control) cells. BDV infection was assayed by BDV nucleoprotein (p40) immunofluorescence, cell proliferation was assayed by Cell Counting Kit-8 (CCK8), and cell cycle phases and apoptosis were assayed by flow cytometry. Expressions of the apoptosis-related proteins Bax and Bcl-2 were measured by Western blotting. p40 expression was confirmed in Hu-H1 and Strain V on and after day three post-infection. Strain V cells showed significantly greater cellular proliferation than Hu-H1 cells on and after day three post-infection. In Hu-H1 cells, Bax and Bcl-2 expression were significantly increased and decreased, respectively, on and after day three post-infection. In contrast, in Strain V cells, Bax and Bcl-2 expression were significantly decreased and increased, respectively, on and after day three post-infection. In conclusion, Hu-H1 inhibits cellular proliferation and promotes apoptosis in human oligodendrocytes via Bax upregulation and Bcl-2 downregulation. In contrast, Strain V promotes cellular proliferation and inhibits apoptosis in human oligodendrocytes via Bax downregulation and Bcl-2 upregulation. The effects of the Hu-H1 strain (isolated from a bipolar patient) are opposite from those of Strain V (a laboratory strain), thereby providing a proof of authenticity for both.

Birds and bornaviruses

In 2008, avian bornaviruses (ABV) were identified as the cause of proventricular dilatation disease (PDD). PDD is a significant condition of captive parrots first identified in the late 1970s. ABV infection has subsequently been shown to be widespread in wild waterfowl across the United States and Canada where the virus infects 10-20% of some populations of ducks, geese and swans. In most cases birds appear to be healthy and unaffected by the presence of the virus; however, infection can also result in severe non-suppurative encephalitis and lesions similar to those seen in parrots with PDD. ABVs are genetically diverse with seven identified genotypes in parrots and one in canaries. A unique goose genotype (ABV-CG) predominates in waterfowl in Canada and the northern United States. ABV appears to be endemic in North American waterfowl, in comparison to what appears to be an emerging disease in parrots. It is not known whether ABV can spread between waterfowl and parrots. The discovery of ABV infection in North American waterfowl suggests that European waterfowl should be evaluated for the presence of ABV, and also as a possible reservoir species for Borna disease virus (BDV), a related neurotropic virus affecting horses and sheep in central Europe. Although investigations have suggested that BDV is likely derived from a wildlife reservoir, for which the shrew and water vole are currently prime candidates, we suggest that the existence of other mammalian and avian reservoirs should not be discounted.

Evaluation of the human host range of bovine and porcine viruses that may contaminate bovine serum and porcine trypsin used in the manufacture of biological products

Current U.S. requirements for testing cell substrates used in production of human biological products for contamination with bovine and porcine viruses are U.S. Department of Agriculture (USDA) 9CFR tests for bovine serum or porcine trypsin. 9CFR requires testing of bovine serum for seven specific viruses in six families (immunofluorescence) and at least 2 additional families non-specifically (cytopathicity and hemadsorption). 9CFR testing of porcine trypsin is for porcine parvovirus. Recent contaminations suggest these tests may not be sufficient. Assay sensitivity was not the issue for these contaminations that were caused by viruses/virus families not represented in the 9CFR screen. A detailed literature search was undertaken to determine which viruses that infect cattle or swine or bovine or porcine cells in culture also have human host range [ability to infect humans or human cells in culture] and to predict their detection by the currently used 9CFR procedures. There are more viruses of potential risk to biological products manufactured using bovine or porcine raw materials than are likely to be detected by 9CFR testing procedures; even within families, not all members would necessarily be detected. Testing gaps and alternative methodologies should be evaluated to continue to ensure safe, high quality human biologicals.

Capture of infectious borna disease virus using anionic polymer-coated magnetic beads

Borna disease virus (BDV) is a noncytolytic, neurotrophic virus that infects a range of vertebrates, including all warm-blooded animals and possibly humans. Although BDV infections are thought to cause neurological disorders, evidence of the presence of the virus in tissues or blood of psychiatric patients is limited, possibly due to the low sensitivity of detection methods. Here, a simple method for capturing BDV has been developed using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). The beads were incubated with lysate from BDV-infected cells, then separated from the supernatant by applying a magnet field and washed. The adsorption of BDV by the beads was confirmed by reverse transcription-polymerase chain reaction and Western blotting, which indicated the presence of the phosphoprotein (P), nucleoprotein (N), and viral genome of BDV on the incubated beads. This method of capture may contribute to the improved detection of BDV.

Heat shock cognate protein 70 controls Borna disease virus replication via interaction with the viral non-structural protein X

Borna disease virus (BDV) is a non-segmented, negative-sense RNA virus and has the property of persistently infecting the cell nucleus. BDV encodes a 10-kDa non-structural protein, X, which is a negative regulator of viral polymerase activity but is essential for virus propagation. Recently, we have demonstrated that interaction of X with the viral polymerase cofactor, phosphoprotein (P), facilitates translocation of P from the nucleus to the cytoplasm. However, the mechanism by which the intracellular localization of X is controlled remains unclear. In this report, we demonstrate that BDV X interacts with the 71kDa molecular chaperon protein, Hsc70. Immunoprecipitation assays revealed that Hsc70 associates with the same region of X as P and, interestingly, that expression of P interferes competitively with the interaction between X and Hsc70. A heat shock experiment revealed that BDV X translocates into the nucleus, dependent upon the nuclear accumulation of Hsc70. Furthermore, we show that knockdown of Hsc70 by short interfering RNA decreases the nuclear localization of both X and P and markedly reduces the expression of viral genomic RNA in persistently infected cells. These data indicate that Hsc70 may be involved in viral replication by regulating the intracellular distribution of X.

Ribavirin inhibits Borna disease virus proliferation and fatal neurological diseases in neonatally infected gerbils

By using neonatal gerbils, we assessed the effect of ribavirin on the proliferation of Borna disease virus (BDV) in the brain. The intracranial inoculation of ribavirin reduced viral propagation in the acutely infected brain, resulting in protection from fatal neurological disorders. We found that the treatment with ribavirin markedly reduces the numbers of OX-42-positive microglial cells, but does not activate expression of Th1 cytokines, in BDV-infected gerbil brains. Our results suggested that ribavirin directly inhibits BDV replication and might be a potential tool for the treatment of BDV infection.

PrPSc level and incubation time in a transgenic mouse model expressing Borna disease virus phosphoprotein after intracerebral prion infection

Our previous studies have shown that the persistent expression of Borna disease virus phosphoprotein (BDV P) in mice leads to behavioral abnormalities resembling those in BDV-infected animals. In this study, we investigated whether the neurobehavioral abnormalities genetically induced by BDV P influence experimental prion disease. The effect of the phosphoprotein on prion diseases was evaluated based on the incubation time and survival curve, as well as the abnormal isoform of prion protein (PrP(Sc)) levels in brains of BDV P Tg mice treated with proteinase K (PK) treatment and subjected to western blotting. Increased expression of the BDV P transgene had no effect on the PrP(Sc) level, incubation time, or survival curve. The abnormalities induced by BDV P are different from those induced by prion diseases, indicating that the signaling cascades induced by the phosphoprotein differ from those induced by prion diseases.

Borna disease virus RNA detected in Japanese macaques (Macaca fuscata)

We have examined the seroprevalence of BDV in wild Japanese macaques (Macaca fuscata) in the peninsula (Chiba prefecture), Japan. Serum samples from macaques were examined by the ELISA, Western blot and immunofluorescence assays to detect the presence of serum antibodies that react specifically to BDV antigens. Among 49 investigated individuals, 6 (12.2%) showed positive reaction to BDV antigens. RT-PCR studies detected BDV sequences in brain tissue of one case among four seropositive cases examined. Sequence analysis revealed a high degree of genetic conservation between BDV sequences derived from Japanese macaques and those documented for other animal species. Nevertheless, phylogenetic analysis revealed unique differences between macaque and other species derived BDV sequences.

Characterization of a Borna disease virus field isolate which shows efficient viral propagation and transmissibility

To investigate the biological characteristics of field isolates of Borna disease virus (BDV), as well as to understand BDV infections outside endemic countries, we isolated the virus from brain samples of a heifer with Borna disease in Japan. We demonstrate that the brain lysate contained replication products of BDV and induced viral propagation in rat glioma cells, suggesting that a replication-competent BDV existed in the bovine brain. This field strain of BDV, named Bo/04w, showed efficient viral release and transmissibility and also displayed a distinct pattern of expression of viral phosphoprotein (P) during infection, as compared with laboratory-adapted BDV strains. Interestingly, we found the level of P to be significantly low in cells infected with Bo/04w, and the transcription of this isolate to be more efficient than that of laboratory strain of BDV. These results indicated that the field isolate may regulate the expression of P at an optimal level in infected cells. We also confirmed that Bo/04w maintains biological significance in neonatal gerbil brain. Sequencing revealed that despite the biological differences, the field isolate is closely related genetically to the laboratory strains of BDV. We discuss here the sequence similarities between BDV isolates from endemic and nonendemic countries.

Reverse-genetic approaches to the study of Borna disease virus

Borna disease virus (BDV) is an enveloped virus that has a non-segmented, negative-strand RNA genome with the characteristic organization of the mononegaviruses. However, based on its unique genetic and biological features, BDV is considered to be the prototypic member of a new mononegavirus family, the Bornaviridae. BDV causes central nervous system (CNS) disease in a wide variety of mammals. This article discusses the recently developed reverse-genetics systems for BDV, and the implications for the elucidation of the molecular mechanisms underlying BDV-host interactions, including the basis of BDV persistence in the CNS and its associated diseases.

No borna disease virus-specific RNA detected in blood of race horses and jockeys

BACKGROUND

Borna disease virus (BDV) predominantly infects horses and sheep, causing a broad range of behavioural disorders. It is controversial whether BDV infects humans and causes psychiatric disorders.

OBJECTIVES

We searched for BDV-derived nucleic acids in blood of race horses and jockeys riding the horses.

METHODS

We assayed for the BDV genome in RNA extracted from peripheral blood mononuclear cells (PBMC) of 39 race horses and 48 jockeys. Two polymerase chain reaction protocols [one-tube reverse transcription-polymerase chain reaction (RT-PCR) and two-step RT-PCR] were used to assay BDV p24 and p40 transcripts.

RESULTS

The p24 and p40 viral nucleic acid sequences were not detected in the PBMC RNAs from any of the race horses or jockeys.

CONCLUSIONS

These data do not support an epidemiological association between BDV infection, race horses and humans.

Prevalence of Borna disease virus antibodies in healthy Japanese black cattle in Kyushu

Epidemiological studies have demonstrated that asymptomatic infection of Borna disease virus (BDV) is found in various species of animals in Japan. Recent reports have also revealed that neurological diseases caused by this virus could exist in horses, cattle, a dog, and cats in this country. In this study, we investigated seroprevalence of BDV antibodies in Japanese black cows reared in Kyushu, the southernmost main island of Japan, using ELISA and Western-immunoblotting. Of 101 serum samples, 11 (10.9%) and 21(20.7%) sera were identified as having antibodies to the BDV N and P antigens, respectively. Among the positive sera, three cows (2.9%) were seropositive for both of the antigens. Furthermore, interestingly, only female cows showed antibodies to P, whereas N antibodies were detected in male and female cows with a comparative ratio. Together with previous studies, our results indicate that BDV might be widely spread in cattle raised in Japan. Furthermore, this is the first report to show that beef cattle, Japanese black cattle, have antibodies against a possible zoonotic pathogen, BDV.

Infecções virais e depressão

OBJETIVO: A associação entre depressão e viroses é estudada há quase dois séculos, com resultados conflitantes. O objetivo deste trabalho é fazer uma análise crítica dos estudos existentes na literatura sobre essa relação. MÉTODOS: A pesquisa bibliográfica utilizou as fontes eletrônicas de busca MEDLINE e LILACS (1966 a agosto 2005). As referências dos artigos foram utilizadas como fonte adicional de consulta. RESULTADOS: Foram abordados os trabalhos que trataram da associação entre depressão e os vírus HIV, HCV, EBV, influenza, HSV, HBV, HAV, BDV e HTLV. A relação entre HIV e depressão mostrou-se bem documentada na literatura. Existem indícios de que a prevalência desse transtorno nos indivíduos infectados pelo HIV seja maior que a encontrada nos soronegativos. Além disso, estudos constataram que a depressão está associada a pior prognóstico da infecção. Quanto à associação entre HCV e depressão, os trabalhos sugeriram maior prevalência desse transtorno psiquiátrico nos portadores do HCV comparados à população geral. Não existem evidências científicas suficientes para dar suporte à relação entre os demais vírus e depressão. CONCLUSÃO: As associações mais bem fundamentadas foram aquelas entre depressão e os vírus HIV e HCV. A relação entre as demais viroses e depressão precisa ser mais bem estudada, e trabalhos com delineamento adequado se fazem necessários.

Borna disease virus interference with neuronal plasticity

Viruses able to infect the central nervous system (CNS) are increasingly being recognized as important factors that can cause mental diseases by interfering with neuronal plasticity. The mechanisms whereby such infections disturb brain functions are beginning to emerge. Borna disease virus (BDV), which causes a persistent infection of neurons without direct cytolysis in several mammalian hosts, has recently gained interest as a unique model to study the mechanisms of viral interference with neuronal plasticity. This review will summarize several hypotheses that have been put forward to explain possible levels of BDV interference with brain function.

Identification of the Borna disease virus (BDV) proteins required for the formation of BDV-like particles

Borna disease virus (BDV) is an enveloped virus with a non-segmented, negative-strand RNA genome that has an organization characteristic of Mononegavirales. However, based on its unique genetics and biological features BDV is considered to be the prototypic member of a new virus family, Bornaviridae. Here, the use of a reverse genetic approach to identify the viral proteins required for packaging of BDV RNA analogues (MG) into infectious virus-like particles (VLPs) was described. Plasmids encoding individual BDV proteins under the control of a RNA polymerase II promoter were co-transfected with a plasmid that allows for intracellular synthesis of a BDV MG mediated by the cellular RNA polymerase I. Clarified lysates from transfected cells were passaged onto fresh cells that were previously transfected with plasmids expressing the minimal BDV trans-acting factors L, N and P required for RNA synthesis mediated by the BDV polymerase. Reconstitution of BDV MG-specific packaging and passage of infectious VLP was monitored by expression of the chloramphenicol acetyl transferase reporter gene present in the BDV MG. BDV M and G, in addition to L, N and P, were sufficient for the passage of chloramphenicol acetyl transferase activity, which could be blocked by BDV neutralizing antibodies to G, indicating that VLP infectivity was fully mediated by BDV G. Passage of BDV MG was abrogated by omission of either M or G.

Functional characterization of the genomic promoter of borna disease virus (BDV): implications of 3'-terminal sequence heterogeneity for BDV persistence

Borna disease virus (BDV) is an enveloped virus with a genome organization characteristic of Mononegavirales. However, based on its unique features, BDV is considered the prototypic member of a new virus family, Bornaviridae, within the order Mononegavirales. We have described the establishment of a reverse genetics system for the rescue of BDV RNA analogues, or minigenomes, that is based on the use of polymerase I/polymerase II. Using this BDV minigenome rescue system, we have examined the functional implications of the reported sequence heterogeneity found at the 5' and 3' termini of the BDV genome and also defined the minimal BDV genomic promoter within the 3'-terminal 25 nucleotides. Our results suggest that the accumulation of RNA genome species containing truncations of one to three nucleotides at their 3' termini may contribute to modulate BDV RNA replication and gene expression during long-term persistence.

The use of peptide arrays for the characterization of monospecific antibody repertoires from polyclonal sera of psychiatric patients suspected of infection by Borna Disease Virus

Borna Disease Virus (BDV) is suspected to infect humans and to be associated with psychiatric disorders. To this date, BDV-reactive antibodies provide the only reliable markers to diagnose human BDV infection. Their diagnostic value, however, was recently questioned by the observation that these antibodies recognize BDV antigen with only low avidity, a typical feature of cross-reacting antibodies. This raised the possibility that the human BDV-reactive antibodies were triggered by other pathogens than BDV. The recent establishment of a peptide array-based screening test allowed the further characterization of these antibodies. It revealed the presence of small amounts of BDV-reactive antibodies in crude human sera that specifically recognized various epitopes of three major BDV proteins. Most importantly, the purified epitope-specific antibodies were shown to bind to BDV antigen with high avidity when assayed by conventional immunofluorescence assay (IFA) or by Western blot. These results are compatible with the view that the presence of BDV-reactive antibodies in human sera reflects an infection with BDV, although the poor affinity maturation remains unexplained. Furthermore, it demonstrates that peptide array-based screening tests are a reliable system for identifying monospecific antibodies from human polyclonal sera with high specificity and sensitivity.

Investigation of frequency of active Borna disease virus infection in Scottish blood donors

BACKGROUND AND OBJECTIVES

Borna disease virus (BDV) can infect a wide range of vertebrate species causing neurological disease. In order to ensure the safety of blood supplies, it is essential to monitor blood for emerging pathogens.

MATERIALS AND METHODS

One-hundred individual white cell pellets and pools representing 25 000 plasma donations from human blood were screened for BDV by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

BDV RNA was not detected in any of the samples.

CONCLUSIONS

The results indicate that BDV is not widely spread in the UK human population and does not represent a risk as a transfusion-transmitted agent.

2'-fluoro-2'-deoxycytidine inhibits Borna disease virus replication and spread

Borna disease virus (BDV) causes neurological diseases in a variety of warm-blooded animal species, possibly including humans. To date, there is no effective treatment against BDV infection. Recently, we reported on the antiviral activity of 1-beta-D-arabinofuranosylcytosine (Ara-C). However, Ara-C's cytotoxic side effects are a major obstacle for its therapeutic use. Herein, we demonstrate that the nucleoside analog 2'-fluoro-2'-deoxycytidine (2'-FdC) exhibits potent antiviral activity against BDV. Importantly, 2'-FdC-associated cytotoxicity is negligible, indicating 2'-FdC as an excellent candidate for the development of antiviral therapy against BDV.

Persistent, non‐cytolytic infection of neurons by Borna disease virus interferes with ERK 1/2 signaling and abrogates BDNF‐induced synaptogenesis

Infection of the central nervous system by Borna disease virus (BDV) provides a unique model to study the mechanisms whereby a persistent viral infection can impair neuronal function and cause behavioral diseases reminiscent of mood disorders, schizophrenia, or autism in humans. In the present work, we studied the effect of BDV infection on the response of hippocampal neurons, the main target for this virus, to the neurotrophin BDNF. We showed that persistent infection did not affect neuronal survival or morphology. However, it blocked BDNF-induced ERK 1/2 phosphorylation, despite normal expression of the TrkB BDNF receptor. In addition, BDNF-induced expression of synaptic vesicle proteins was abrogated, which resulted in severely impaired synaptogenesis and defects in synaptic organization. Thus, we provide the first evidence that a virus can interfere specifically with neurotrophin-regulated neuroplasticity, thereby hampering proper neuronal connectivity. These results may help to understand the behavioral disorders associated with BDV infection.

Borna disease virus RNA in immunocompromised patients in southwestern France

Borna disease virus (BDV) is a neurotropic RNA virus with a wide host range. Human infections, although controversial, have been described in Europe, Asia, and the United States. The present study investigated the existence of BDV infections in immunocompromised human beings, namely, 82 human immunodeficiency virus (HIV)-infected and 80 therapeutically immunosuppressed patients. BDV p40 RNAs were detected in peripheral white blood cells with reverse transcription-nested PCR and hybridization in, respectively, 11 (13.41%) and 1 (1.25%) of the two groups of patients. BDV p24 RNAs were identified in only one of those. BDV RNA was detected in the absence of any neuropsychiatrical illness, suggesting that BDV infections may occur in asymptomatic carriers. The severity and particularity of cellular immunosuppression could explain the significantly increased detection of BDV RNA in HIV-infected patients.

Virus-induced neurobehavioral disorders: mechanisms and implications

One hypothesis for the etiology of neuropsychiatric disorders proposes that viral infection contributes to the induction of neuronal system dysfunction, resulting in a wide range of behavioral abnormalities. Recent research in molecular biology supports this hypothesis and refocuses on the role of viral infection in the development of psychiatric disorders. Viral infection can induce deleterious effects in the central nervous system by direct and/or indirect pathways. Understanding the mechanisms of glial cell dysfunction caused by persistent viral infection should lead to novel insights into the development of neurobehavioral disorders, including human mental illnesses, and to the possible development of treatments.

Borna disease virus phosphoprotein represses p53-mediated transcriptional activity by interference with HMGB1

Borna disease virus (BDV) is a noncytolytic, neurotropic RNA virus that has a broad host range in warm-blooded animals, probably including humans. Recently, it was demonstrated that a 24-kDa phosphoprotein (P) of BDV directly binds to a multifunctional protein, amphoterin-HMGB1, and inhibits its function in cultured neural cells (W. Kamitani, Y. Shoya, T. Kobayashi, M. Watanabe, B. J. Lee, G. Zhang, K. Tomonaga, and K. Ikuta, J. Virol. 75:8742-8751, 2001). This observation suggested that expression of BDV P may cause deleterious effects in cellular functions by interference with HMGB1. In this study, we further investigated the significance of the binding between P and HMGB1. We demonstrated that P directly binds to the A-box domain on HMGB1, which is also responsible for interaction with a tumor suppression factor, p53. Recent works have demonstrated that binding between HMGB1 and p53 enhances p53-mediated transcriptional activity. Thus, we examined whether BDV P affects the transcriptional activity of p53 by interference with HMGB1. Mammalian two-hybrid analysis revealed that p53 and P competitively interfere with the binding of each protein to HMGB1 in a p53-deficient cell line, NCI-H1299. In addition, P was able to significantly decrease p53-mediated transcriptional activation of the cyclin G promoter. Furthermore, we showed that activation of p21(waf1) expression was repressed in cyclosporine-treated BDV-infected cells, as well as p53-transduced NCI-H1299 cells. These results suggested that BDV P may be a unique inhibitor of p53 activity via binding to HMGB1.