Demonstration of Borna disease virus RNA in peripheral blood mononuclear cells from healthy horses in Japan

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Borna disease

Borna disease has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of Borna disease to be listed, Article 9 for the categorisation of Borna disease according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to Borna disease. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, Borna disease cannot be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL because there was no compliance on criterion 5 A(v). Consequently, the assessment on compliance of Borna disease with the criteria as in Annex IV of the AHL, for the application of the disease prevention and control rules referred to in Article 9(1) is not applicable, as well as which animal species can be considered to be listed for Borna disease according to Article 8(3) of the AHL.

Glutamate and lipid metabolic perturbation in the hippocampi of asymptomatic borna disease virus-infected horses

Borna disease virus (BDV) is a neurotropic, enveloped, non-segmented, negative-stranded RNA virus that infects a wide variety of vertebrate species from birds to humans across a broad global geographic distribution. Animal symptomatology range from asymptomatic infection to behavioral abnormalities to acute meningoencephalitis. Asymptomatic BDV infection has been shown to be more frequent than conventionally estimated. However, the molecular mechanism(s) underyling asymptomatic BDV infection remain largely unknown. Here, based on real-time quantitative PCR and Western blotting, a total of 18 horse hippocampi were divided into BDV-infected (n = 8) and non-infected control (n = 10) groups. A gas chromatography coupled with mass spectrometry (GC-MS) metabolomic approach, in conjunction with multivariate statistical analysis, was used to characterize the hippocampal metabolic changes associated with asymptomatic BDV infection. Multivariate statistical analysis showed a significant discrimination between the BDV-infected and control groups. BDV-infected hippocampi were characterized by lower levels of D-myo-inositol-1-phosphate, glutamate, phosphoethanolamine, heptadecanoic acid, and linoleic acid in combination with a higher level of ammonia. These differential metabolites are primarily involved in glutamate and lipid metabolism. These finding provide an improved understanding of hippocampal changes associated with asymptomatic BDV infection.

Evidence for natural Borna disease virus infection in healthy domestic animals in three areas of western China

Borna disease virus (BDV) is a non-cytolytic, neurotropic RNA virus that can infect many vertebrate species, including humans. To date, BDV infection has been reported in a range of animal species across a broad global geographic distribution. However, a systematic epidemiological survey of BDV infection in domesticated animals in China has yet to be performed. In current study, BDV RNA and antibodies in 2353 blood samples from apparently healthy animals of eight species (horse, donkey, dog, pig, rabbit, cattle, goat, sheep) from three areas in western China (Xinjiang province, Chongqing municipality, and Ningxia province) were assayed using reverse transcription qPCR (RT-qPCR) and ELISA assay. Brain tissue samples from a portion of the BDV RNA- and/or antibody-positive animals were subjected to RT-qPCR and western blotting. As a result, varying prevalence of BDV antibodies and/or RNA was demonstrated in various animal species from three areas, ranging from 4.4 % to 20.0 %. Detection of BDV RNA and/or antibodies in Chongqing pigs (9.2 %) provided the first known evidence of BDV infection in this species. Not all brain tissue samples from animals whose blood was BDV RNA and/or antibody positive contained BDV RNA and protein. This study provides evidence that BDV infection among healthy domestic animal species is more widespread in western China than previously believed.

Borna disease virus antibody and RNA from peripheral blood mononuclear cells of race horses and jockeys in Korea

OBJECTIVE

During the last two decades, Borna disease virus (BDV) has received much attention as a possible zoonotic agent, particularly as a cause of psychiatric disease. Although several studies have shown that BDV is present in Asia, BDV has not been detected in Korea. This study was designed to further investigate the presence of BDV infection in Korea.

METHODS

Blood samples were taken from 39 race horses and 48 jockeys. Antibody to BDV was detected by indirect immunofluorescence antibody test and RNA of BDV by real time reverse transcriptase PCR (rRT-PCR).

RESULTS

No evidence of BDV was detected in either the horses or the jockeys group.

CONCLUSION

Our results suggest that BDV infection may not be endemic in Korea. Further studies with novel diagnostic tools are required to clarify the prevalence of BDV infection in Korea.

Borna disease virus in Raccoons (Procyon lotor) in Japan

We have examined the seroprevalence of BDV in wild Raccoons (Procyon lotor) in Hokkaido, Japan. Serum samples from raccoons were examined using ELISA and Western blot assays to detect the presence of serum antibodies that react specifically to BDV antigens. Among 549 investigated individuals, eleven (2.0%) showed a positive reaction to BDV antigens. Brain tissue samples from five individuals were subjected to RT-PCR, which detected BDV sequences in three of them. Sequence analysis revealed a high degree of genetic conservation between BDV sequences derived from raccoons and previously published sequences derived from other animal species.

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.

Development of a real-time RT-PCR assay for improved detection of Borna disease virus

Borna disease virus (BDV) is a non-segmented, negative-stranded RNA virus, which infects cells of the central nervous system (CNS) in many different species. BDV is the causative agent of the neurological disorders in horses and sheep termed classical Borna disease (BD), as well as staggering disease in cats. At present, the diagnosis staggering disease or feline BD is made by histopathology or immunohistochemistry of the CNS. In order to obtain a better clinical diagnostic tool, a duplex real-time RT-PCR assay (rRT-PCR) was developed. TaqMan probes and primers specific for the BDV P and BDV L genes were designed by aligning the sequences of known BDV strains. After optimisation, the sensitivity and specificity of the rRT-PCR were established. The detection limit was set to 10-100 viral genomic copies per reaction and the assay detects the BDV strains V and He/80, as well as the most divergent BDV strain known so far, No/98. Furthermore, the system detected feline BDV variants in five naturally infected cats and a feline isolate used in experimental infection of cats. This rRT-PCR assay will be a powerful tool in further studies of BDV, including epidemiological screening and diagnosis.

Expression of allograft inflammatory factor-1 and haeme oxygenase-1 in brains of rats infected with the neurotropic Borna disease virus

Experimental infection of Lewis rats with Borna disease virus (BDV) causes an immune-mediated nonpurulent meningoencephalitis. Viral persistence in the central nervous system is accompanied by mononuclear infiltrates, activated monocytic/microglial cells and reactive astrocytes. The immune-mediated process was further characterized by expression analysis of allograft inflammatory factor-1 (AIF-1), a novel marker of monocyte/microglial activation and of glial fibrillary acid protein (GFAP) between day 3 and day 50 post infection (p.i.). Potential neuroprotective effects of these cells were studied by the induction of haeme oxygenase-1 (HO-1), a defensive molecule against oxidative stress in various brain insults. In BDV-infected rat brains, mononuclear infiltrates and AIF-1 expression increased up to day 28 p.i. During early time points p.i., AIF-1 expression was mainly found in inflammatory lesions and adjacent brain parenchyma. Already 24 days p.i., a widespread upregulation of AIF-1 was observed which declined only moderately beyond day 28 p.i. HO-1 induction was maximal between days 18 and 28 p.i. Increased amounts of GFAP-positive astrocytes were present beyond 24 days p.i. Viral antigen expression increased simultaneously to the inflammatory reaction and persisted up to 50 days p.i. Widespread upregulation of AIF-1 indicates an early, long-lasting microglial activation, which might be involved in the immunesurveillance of the immune-mediated inflammatory events. The early peak of HO-1 most likely represents a neuroprotective, anti-inflammatory response by invading monocytes, microglial cells and astrocytes during the formation of encephalitic lesions and acute viral replication.

Nosological study of Borna disease virus infection in race horses

To investigate the prevalence of diseases in the Borna disease virus (BDV) antibody positive race horses, we undertook seroepidemiological studies of BDV infection on 125 culled race horses in Hokkaido, Japan. The serological study disclosed the presence of antibodies only to BDV-p40 or -p24 in 19.2% (24/125) and 3.2% (4/125) of culled horses, respectively. Antibodies to both BDV-p40 and -p24 were found in 24.0% (30/125) of these horses. Of particular note was the finding that locomotorium disorders were detectable at a significantly higher rate in BDV antibody positive horses than that in the seronegative horses. These results imply that BDV infection may possibly contribute to an increase in the incidence rate of locomotorium disorders in race horses.

Evidence of Borna disease virus genome detection in French domestic animals and in foxes (Vulpes vulpes)

Borna disease virus (BDV) is an enveloped, non-segmented negative-stranded RNA virus which belongs to the Bornaviridae family. BDV is an aetiological agent of encephalitis in horses, sheep and several other vertebrate species. In order to extend our knowledge about the presence of BDV in France, a study based on BDV RNA detection by RT-nested-PCR was done with 196 animal tissues: 171 brain samples collected from different animal species (75 horses, 59 foxes, 31 cattle, 4 dogs, 1 sheep, 1 roe deer) and 25 horse blood samples. An RNA internal standard molecule was constructed and was co-amplified with the test template. This study reports the first detection of BDV RNA in France in 10 brain samples collected from horses, foxes and cattle, and from 14 horse blood samples. Detection of the BDV genome in the brains of six red foxes is the first evidence of BDV infection in this species.

Seroprevalence of Borna disease virus in domestic animals in Xinjiang, China

To investigate the animals infected with Borna disease virus (BDV) in Xinjiang, China, we examined for BDV antibodies in the sera from groups of 20 horses, sheep and cattle, and from 165 wild rodents (18 species) by ELISA and immunoblot. The serological study disclosed the presence of antibodies to both BDV-p24 and -p40 in the horses (20%) and sheep (25%), whereas no apparent positive reaction was detected either in cattle or rodents. The results suggested that BDV is prevalent in horses and sheep in the district investigated.

Borna disease virus

Borna disease virus (BDV) is unique amongst animal RNA viruses in its molecular biology and capacity to cause persistent, noncytolytic CNS-infection in a wide variety of host species. Unlike other non-segmented negative-strand RNA animal viruses, BDV replicates in the nucleus of the host cell where splicing is employed for expression of a very compact genome. Epidemiological studies indicate a broad host range and geographical distribution, and some investigators have proposed that human infection may result in neuropsychiatric disorders. Experimental Borna disease in neonatal and adult rats provides an intriguing model for immune-mediated disturbances of brain development and function.

Detection of Borna disease virus in a pregnant mare and her fetus

A pregnant mare showing pyrexia, reduced appetite, ataxia and paresis was euthanized and examined for the presence of Borna disease virus (BDV). Her brain, showing multiple neuronal degeneration and necrosis with hemorrhage, and the histologically normal brain of the fetus were both positive for BDV RNA. The BDV nucleotide sequences were identical in the mare and fetus in the second open reading frame (ORF). This is the first report of the possible vertical transmission of BDV in a horse.

Detection of borna disease virus-reactive antibodies from patients with psychiatric disorders and from horses by electrochemiluminescence immunoassay

The prevalence of Borna disease virus (BDV)-specific antibodies among patients with psychiatric disorders and healthy individuals has varied in several reports using several different serological assay methods. A reliable and specific method for anti-BDV antibodies needs to be developed to clarify the pathological significance of BDV infections in humans. We developed a new electrochemiluminescence immunoassay (ECLIA) for the antibody to BDV that uses two recombinant proteins of BDV, p40 and p24 (full length). Using this ECLIA, we examined 3,476 serum samples from humans with various diseases and 917 sera from blood donors in Japan for the presence of anti-BDV antibodies. By ECLIA, 26 (3.08%) of 845 schizophrenia patients and 9 (3.59%) of 251 patients with mood disorders were seropositive for BDV. Among 323 patients with other psychiatric diseases, 114 with neurological diseases, 75 with chronic fatigue syndrome, 85 human immunodeficiency virus-infected patients, 50 with autoimmune diseases including rheumatoid arthritis and systemic lupus erythematosis and 17 with leprosy, there was no positive case except one case each with alcohol addiction, AIDS, and dementia. Although 19 (1.36%) of 1,393 patients with various ocular diseases, 10 (1.09%) of 917 blood donors, and 3 (4.55%) of 66 multitransfused patients were seropositive for BDV-specific antigen, high levels of seroprevalence in schizophrenia patients and young patients (16 to 59 years old) with mood disorders were statistically significant. The immunoreactivity of seropositive sera could be verified for specificity by blocking with soluble p40 and/or p24 recombinant protein. Anti-p24 antibody was more frequent than p40 antibody in most cases, and in some psychotic patients antibody profiles showed only p40 antibody. Although serum positive for both p40 and p24 antibodies was not found in this study, the p40 ECLIA count in schizophrenia patients was higher than that of blood donors. Furthermore, we examined 90 sera from Japanese feral horses. Antibody profiles of control human samples are similar to that of naturally BDV-infected feral horses. We concluded that BDV infection was associated in some way with psychiatric disorders.

Inhibition of Borna disease virus replication by ribavirin

The guanosine analogue ribavirin was tested for antiviral activity in two neural cell lines, human oligodendrocytes and rat glia, against Borna disease virus (BDV) strains V and He/80. Ribavirin treatment resulted in lower levels of virus and viral transcripts within 12 h. Addition of guanosine but not adenosine resulted in a profound reduction of the ribavirin effect. Ribavirin appears to be an effective antiviral agent for treatment of BDV infection in vitro. A likely mechanism for its activity is reduction of the intracellular GTP pool, resulting in inhibition of transcription and capping of BDV mRNAs.

Peripheral and intracerebral T cell immune response in cats naturally infected with Borna disease virus

Borna disease virus (BDV) is a neurotropic agent with capacity to cause encephalomyelitis in a wide range of animal species, including horses and cats. Recent studies also point to a link between BDV and human neuropsychiatric disorders. The pathogenesis of Borna disease (BD) has been proposed to be immune-mediated, mainly through the effects of cytotoxic T cells. We used flow cytometric analysis in order to characterize the peripheral and intracerebral T cell immune response in cats naturally infected with BDV. Our results show the presence of two different CD8+ cell populations (CD8+low and CD8+high) in the blood, spleen and brain of these cats. In the brain, CD8+low cells predominated over CD8+high cells. Since CD8+low cells have been suggested to represent a non-MHC-restricted T cell population, the recruitment of such cells to the brains of BDV-infected cats could possibly be of importance for the clearance of virus from neurones.

High susceptibility of Mongolian gerbil (Meriones unguiculatus) to Borna disease virus

Borna disease virus (BDV) is a neurotropic enveloped virus with a nonsegmented, single-, negative-stranded RNA genome. This virus induced encephalitis in experimentally infected adult rats, but in newborn rats BDV established a persistent, tolerant infection with no apparent clinical signs. Here, we report evidence that newborn Mongolian gerbils (Meriones unguiculatus) are more susceptible to experimental intracranial inoculation of horse-derived BDV in persistently infected MDCK cells, compared with similar inoculation in newborn rats. All inoculated newborn gerbils, but not rats, died 30 days after infection. Reverse transcriptase-polymerase chain reaction amplified BDV-specific sequences in several regions including the brain. Histopathological analysis revealed apparent inflammatory reactions in the brains of inoculated gerbils but not rats, although similar levels of BDV RNA were detected in both gerbil and rat brains. BDV-specific antigen and RNA were identified predominantly in neurons in the brains by immunohistochemistry with antibodies to BDV and in situ hybridization with BDV-specific riboprobes, respectively. BDV in the gerbil brain was easily rescued by co-cultivation of the brain homogenate with human oligodendroglioma cells. Thus, gerbils seem to be a useful animal model for studying BDV-induced pathogenesis in the brain.

A serosurvey of Borna disease virus infection in wild rats by a capture ELISA

For a serological diagnostic test for Borna disease (BD), we developed a capture ELISA with specificity and sensitivity based on detection of antibodies against BD virus (BDV) p40 protein. Using our capture ELISA system, the antibody response of rats inoculated intracerebrally with BDV at 4 weeks after birth showed a sharp increase from 1 to 4 weeks postinoculation (p.i.) and a steady level after 5 weeks p.i. To investigate prevalence of BDV infection among wild rats, we examined sera of Rattus norvegicus in Kami-iso town, Oshima district, Hokkaido, suggesting that rats in this area had not been infected by BDV.

Reverse transcription-nested polymerase chain reaction for detecting p40 RNA of Borna disease virus, without risk of plasmid contamination

Several methods for the detection of Borna disease virus (BDV) RNA have been reported, one being the reverse transcription-nested polymerase chain reaction (RT-nested PCR) method. However, due to the possibility of contamination of the cloned DNA in a reaction tube, false-positive results might be obtained by RT-nested PCR. To detect only BDV RNA without anxiety of contamination, we developed an RT-nested PCR system using "mRNA selective PCR kit". Using this system, cDNA of BDV p40 in the plasmid (up to 5 x 10(7) molecules) was not amplified. BDV specific sequence was amplified from total RNA (more than 50 pg) of MDCK/BDV cells, which were persistently infected with BDV. These results indicate that this mRNA selective RT-nested PCR system can specifically amplify target RNA as distinguished from plasmid contaminated.

Borna disease in a dog with lethal meningoencephalitis

A dog was euthanatized because of progressive neurological signs. Histologically, a nonsuppurative meningoencephalitis was found. By immunohistochemistry, in situ hybridization, and nested PCR procedures, Borna disease virus (BDV) antigen and BDV-specific RNA were demonstrated in brain tissues of the dog. The nucleotide sequence of the PCR product showed 94 to 98% homology to published BDV sequences. This is the first description of Borna disease in a dog.

Evaluation of serological diagnosis of Borna disease virus infection using recombinant proteins in experimentally infected rats

We produced two recombinant Borna disease virus (BDV) proteins, p40 and p24, by using a baculovirus vector as a diagnostic antigen. Antigenicities of these recombinant proteins were evaluated by immune rabbit sera. Recombinant p40 was a more sensitive antigen than p24 for the detection of antibodies in infected rats. Rats inoculated with BDV within 24 hr after birth showed higher detection rates of viral RNA and viral proteins from the brain than rats inoculated at 4 weeks-old. Depending on the age of infection and the time postinfection, the detection of BDV RNA, protein, or anti-BDV antibody did not always correlate in individuals. We suggest both serological and molecular biological methods are needed in the diagnosis of BDV infection.

Sensitivity and reproducibility of RT-PCR to detect Borna disease virus (BDV) RNA in blood: implications for BDV epidemiology

Borna disease virus (BDV) infection of domestic animals and humans appears to have a worldwide distribution. There is evidence suggesting an association of BDV with certain psychiatric disorders. However, more comprehensive epidemiological studies are required to establish rigorously a link between BDV and human mental disorders, and to evaluate the role of carrier animals as potential source of BDV for human infection. The use of RT-PCR to detect BDV RNA in peripheral blood mononuclear cells (PBMCs) of infected individuals is a powerful tool to address these questions. The comparison of discrepant results reported by different investigators using this approach is hampered by the lack of controls to assess the sensitivity and reproducibility of the assays. Procedures are now described that allow the establishment of standardized controls to evaluate the performance of the RT-PCR assays. This RT-PCR assay detected reproducibly 100 copies of BDV p40 RNA in 5 microg of RNA. The data illustrate that the number of PBMCs used for RNA preparation, rather than the amount of RNA, has a critical influence on the outcome of the RT-PCR assay. Evidence is provided that levels of BDV in blood do not necessarily reflect viral load in brain.

Spontaneous Borna disease in sheep and horses: immunophenotyping of inflammatory cells and detection of MHC-I and MHC-II antigen expression in Borna encephalitis lesions

Borna disease (BD) has been recognized as a virally induced T-cell dependent immunopathological disorder of the central nervous system (CNS), as shown by experimental infection of rats with Borna disease virus (BDV). In contrast to the rat model, little is known about the pathogenesis of spontaneous BD in sheep and horses. The present study describes the brain lesions of 12 ovine and 11 equine cases of naturally occurring BD. A set of monoclonal and polyclonal antibodies was used in order to determine the cells operative in encephalitic lesions and to detect expression of MHC-I and MHC-II products in the brains of affected animals. In all cases investigated, a reaction pattern similar to that reported for the acute phase of BD in experimentally infected rats was noted. In brief, the majority of inflammatory cells in perivascular infiltrates (PVI) as well as parenchymal and meningeal infiltrates were CD3 +. CD4 + cells outnumbered CD8 + cells in PVI as well as in the parenchyma. Macrophages (defined by lysozyme immunoreactivity) were seen less often and B-cells or plasma cells (cells positive for lambda or kappa light chains) were demonstrated at lower numbers. TCR-1 + cells were found on very rare occasions in PVI of some sheep. MHC-I and MHC-II products were constantly expressed on inflammatory cells but inconsistently on astrocytes and neurons. Neuronal degeneration was not a major feature.

High prevalence of Borna disease virus infection in healthy sheep in Japan

Previous seroepidemiological and molecular epidemiological studies of Borna disease virus (BDV) showed considerably high rates of infection in horses, cattle, cats, and humans in Hokkaido, Japan. Here, we further demonstrate high rates of specific antibodies to BDV and BDV RNA in peripheral blood mononuclear cells (PBMCs) from healthy sheep bred on the same island. The BDV prevalences by immunoblotting and/or reverse transcriptase PCR were 0% (0 of 19) in newborns (<1 month old), 51.7% (15 of 29) in lambs (1 to 6 months old), and 36.7% (11 of 30) in adults (>2 years old). Among animals positive for BDV, 60% of lambs and 45.5% of adults contained BDV RNA in PBMCs while 46.7% of lambs and 90.9% of adults contained specific antibodies to BDV. Thus, it is suggested that virus replication in the blood, as observed in lambs, is usually reduced in adulthood by raising immune responses to BDV.

Borna disease virus (BDV), a (zoonotic?) worldwide pathogen. A review of the history of the disease and the virus infection with comprehensive bibliography

A comprehensive history of Borna disease virus (BDV) and this infection, including the complete bibliography, is presented. Over the last 200 years, descriptions of this 'head disease' of horses ('Kopfkrankheit der Pferde') have been given. Considerable losses in the horse population (< 0.8%) led to intensive clinical and (neuro-)pathological investigations of this meningitis cerebrospinalis which occurs with faint behavioural changes, occasionally followed by severe neurological symptomatology and death. The broad experimental host range reflects infections in nature which include horses, sheep, cattle, cats, dogs, rodents, ostriches, and some zoo animals. BDV infections are associated with phylogentically old brain areas, and the retina. Occasionally, expression in the autonomic nervous system occurs, besides its neurotropism BDV can spread to peripheral organs, especially to epithelial tissues and peripheral blood mononuclear cells. Infections of humans that can be monitored by antibodies, antigens or nucleic acids in blood samples are prominent features of future interest. BDV, the prototype of the family Bornaviridae is an enveloped spherical virus carrying an 8.9 kb single-stranded, non-segmented RNA with negative polarity which replicates in the nucleus. These features together with its considerable genetic stability make this non-cytopathogenic virus an evolutionary 'old pathogen' in nature.

Borna disease virus infection in animals and humans

The geographic distribution and host range of Borna disease (BD), a fatal neurologic disease of horses and sheep, are larger than previously thought. The etiologic agent, Borna disease virus (BDV), has been identified as an enveloped nonsegmented negative-strand RNA virus with unique properties of replication. Data indicate a high degree of genetic stability of BDV in its natural host, the horse. Studies in the Lewis rat have shown that BDV replication does not directly influence vital functions; rather, the disease is caused by a virus-induced T-cell mediated immune reaction. Because antibodies reactive with BDV have been found in the sera of patients with neuropsychiatric disorders, this review examines the possible link between BDV and such disorders. Seroepidemiologic and cerebrospinal fluid investigations of psychiatric patients suggest a causal role of BDV infection in human psychiatric disorders. In diagnostically unselected psychiatric patients, the distribution of psychiatric disorders was found to be similar in BDV seropositive and seronegative patients. In addition, BDV-seropositive neurologic patients became ill with lymphocytic meningoencephalitis. In contrast to others, we found no evidence is reported for BDV RNA, BDV antigens, or infectious B DV in peripheral blood cells of psychiatric patients.

Borna disease virus and the brain

Viruses with the ability to establish persistent infection in the central nervous system (CNS) can induce progressive neurologic disorders associated with diverse pathological manifestations. Clinical, epidemiological, and virological evidence supports the hypothesis that viruses contribute to human mental diseases whose etiology remains elusive. Therefore, the investigation of the mechanisms whereby viruses persist in the CNS and disturb normal brain function represents an area of research relevant to clinical and basic neurosciences. Borna disease virus (BDV) causes CNS disease in several vertebrate species characterized by behavioral abnormalities. Based on its unique features, BDV represents the prototype of a new virus family. BDV provides an important model for the investigation of the mechanisms and consequences of viral persistence in the CNS. The BDV paradigm is amenable to study virus-cell interactions in the CNS that can lead to neurodevelopmental abnormalities, immune-mediated damage, as well as alterations in cell differentiated functions that affect brain homeostasis. Moreover, seroepidemiological data and recent molecular studies indicate that BDV is associated with certain neuropsychiatric diseases. The potential role of BDV and of other yet to be uncovered BDV-related viruses in human mental health provides additional impetus for the investigation of this novel neurotropic infectious agent.

Borna disease

Borna disease virus, a newly classified nonsegmented negative-strand RNA virus with international distribution, infects a broad range of warm-blooded animals from birds to primates. Infection causes movement and behavioral disturbances reminiscent of some neuropsychiatric syndromes. The virus has not been clearly linked to any human disease; however, an association between infection with the virus and selected neuropsychiatric disorders has been suggested. We reviewed recent advances in Borna disease virus research, focusing on evidence of infection in humans.

Detection of Borna disease virus (BDV) antibodies and BDV RNA in psychiatric patients: evidence for high sequence conservation of human blood-derived BDV RNA

In several vertebrate species, Borna disease virus (BDV), the prototype of a new group of animal viruses, causes central nervous system disease accompanied by diverse behavioral abnormalities. Seroepidemiological data indicate that BDV may contribute to the pathophysiology of certain human mental disorders. This hypothesis is further supported by the detection of both BDV antigens and BDV RNA in peripheral blood mononuclear cells (PBMCs) of patients with psychiatric disorders and the isolation of BDV from such PBMCs. Here we describe serological and molecular epidemiological studies on psychiatric patients and healthy individuals from the area of Homburg, Germany. Using a novel Western blot (immunoblot) assay, we found a BDV seroprevalence of 9.6% among 416 neuropsychiatric patients, which is significantly higher than the 1.4% found among 203 healthy control individuals. Human sera displayed a prominent immunoreactivity against the virus nucleoprotein, the p40 antigen. Reverse transcriptase-mediated PCR analysis of RNA extracted from PBMCs of a subset of 26 of the neuropsychiatric patients revealed that 50% were BDV RNA positive. Three of the 13 BDV RNA-positive patients also had BDV-positive serology, whereas one patient with serum antibodies to BDV p40 antigen did not harbor detectable BDV RNA in PBMCs. BDV p40 and p24 sequences derived from human PBMCs exhibited both a high degree of inter- and intrapatient conservation and a close genetic relationship to animal-derived BDV sequences.

Varied prevalence of Borna disease virus infection in Arabic, thoroughbred and their cross-bred horses in Iran

Borna disease virus (BDV) naturally infects horses and sheep and induces progressive poliomeningoencephalomyelitis. Here, BDV recombinant proteins of the first open reading frame (ORF-I; coding for p40 nucleoprotein) and the second ORF-II (coding for p24 polymerase cofactor) were immunoblotted with plasma derived from 72 healthy (28 Arabic, 17 thoroughbred and 27 cross-bred) race horses at Tehran in Iran to detect anti-BDV antibodies. In addition, their peripheral blood mononuclear cells (PBMCs) were also examined for BDV RNA by a nested reverse transcriptase-polymerase chain reaction (RT-PCR) at ORF-II. The prevalence of BDV antibodies and/or RNA was 41.2% in Arabic, 23.5% in thoroughbred, and 33.3% in cross-bred horses, but only 17.9, 5.9, and 11.1% of them, respectively, showed positive signals for both BDV antibodies and RNA. Especially, cross-bred horses showed a higher prevalence for BDV RNA, which was detected only in females. In addition, significantly higher prevalence for BDV RNA was observed in Arabic males and thoroughbred females. The BDV prevalence did not increase with aging of the horse. Sequencing at the region of BDV derived from Iranian horses revealed a slight difference from those of Japanese horse- and European horse-derived BDVs even in the amino acid residues, although those in the three groups of Iranian horses were quite similar. Thus, the varied prevalence of BDV was observed with the horse strain or sex in Iranian horses, although BDV sequences were very similar among all three groups in Iran compared with those derived from other countries.

Unusually high seroprevalence of Borna disease virus in clade E human immunodeficiency virus type 1-infected patients with sexually transmitted diseases in Thailand

The seroprevalence of Borna disease virus (BDV) in human immunodeficiency virus type 1-infected individuals in Thailand was examined by using recombinant BDV p24. A high (38 to 48%) rate of seroprevalence of BDV was observed in clade E-infected patients with sexually transmitted diseases, compared with those in clade E-infected prostitutes (8.3%), pregnant women (0%), clade B-infected intravenous-drug users (0%), and human immunodeficiency virus type 1-negative blood donors (1.9%).

Demonstration of Borna disease virus RNA in peripheral blood mononuclear cells derived from Japanese patients with chronic fatigue syndrome

CFS, a recently named heterogeneous disorder, is an illness of unknown etiology. The association of CFS with viral infections has been suggested. A common association between CFS and several viruses examined has not been confirmed. Here, we centered on the possible link between CFS and BDV infection. By nested RT-PCR followed by hybridization, BDV RNA was demonstrated as a clear signal in PBMCs in 3 out of 25 CFS patients. The amplified cDNA fragments were cloned and sequenced. A total of 16 clones were studied. Intra-patients divergencies of the p24 were 2-9%, 3-20%, and 3-11% in the deduced amino acids. Inter-patient divergencies among the 16 clones were 3-24%. Antibodies to recombinant BDV p24 protein were detected in 6 CFS patients including one carrying BDV RNA. Overall, these gave the prevalence of 32% (8/25) in Japanese CFS patients, suggesting that Japanese CFS is highly associated with active infection of BDV, or a related agent.

Demonstration of borna disease virus RNA in peripheral blood mononuclear cells derived from domestic cats in Japan

Borna disease virus (BDV) naturally infects horses, sheep, and several other species, including humans, and it is believed to be related to neurological disorders. BDV infection in domestic cats has also been demonstrated by serological assays. We demonstrated for the first time BDV RNA in peripheral blood mononuclear cells from 11 of 83 (13.3%) randomly selected domestic cats in Japan by nested reverse transcriptase-PCR. The BDVs from cats were similar to but slightly different from those from horses and humans, as shown by sequencing the reverse transcriptase-PCR products. None of the cats was positive for both BDV RNA and anti-BDV antibodies.

Prevalence of Borna disease virus RNA in peripheral blood mononuclear cells from blood donors

The presence of Borna disease virus (BDV) in peripheral blood mononuclear cells (PBMC) of 100 blood donors from Sapporo and 72 blood donors from Tokyo was examined using nested reverse transcriptase/polymerase chain reaction amplification with specific-primers for BDV p24. Anti-BDV p24 antibodies in the plasma of the 100 blood donors from Sapporo also were studied by enzyme-linked immunosorbent assay and by Western blot. BDV RNA was detected in 3 (4.2%) of the 72 PBMC samples from Tokyo, and in 5 (5%) of the 100 PBMC samples from Sapporo. In contrast, anti-p24 antibodies were found in only 1 (1%) of the donors from Sapporo. These results suggest that BDV infection in humans may be more widespread than previously thought.