Borna Disease Virus P24 Research Articles

Application of antibodies against Borna disease virus phosphoprotein and nucleoprotein on paraffin sections.

In order to study the application of antibodies against recombinant proteins for detecting Borna disease virus (BDV) phosphoprotein (p24) and nucleoprotein (p40) (BDV‑p24/p40) on paraffin sections by immunohistochemistry. The purified fusion p24 and p40 proteins were used for the preparation of polyclonal and monoclonal anti‑p24 and anti‑40 antibodies, which were confirmed by ELISA and western blotting. Paraffin sections were made from BDV‑infected Sprague‑Dawley (SD) rats (n=20), PBS‑injected SD rats (n=20), normal SD rats (n=20) and normal C57 mice (n=20). Immunohistochemical staining was performed according to the EnVision™ two‑step protocol. Heat‑mediated antigen retrieval was performed using the retrieval buffer sodium citrate (1mM; pH6.0). All the antibodies against recombinant proteins exhibited good sensitivity and specificity. There were significant differences between the BDV‑infected group and the BDV‑uninfected group for poly‑ and monoclonal anti‑p24 and ‑p40 antibodies. These antibodies against recombinant proteins may be used effectively to detect BDV p24 and p40 in paraffin sections.

Infection of Borna disease virus in healthy animals in northern China

Borna disease virus (BDV) is a non-segmented, single negative stranded RNA virus. It is highly neurotropic, but the infection is not cytopathic to the infected cells. BDV is widely infected in vertebrates, causing abnormal behavior and multiple pathological changes. Horses and sheep are the main natural hosts of BDV. Borna disease (BD) is characterized by progressive mononuclear encephalomyelitis. The BD clinical manifestations include ataxia, depression, rotation movement, mandatory standing, hitting objects with body and paralysis, and they usually last for 1-3 weeks. BDV infection causes a significant health problem in animals and economic loss for the society. However, BDV natural infection frequency in the raised animals in northern China, is poorly understood, but is required for understanding BDV infection epidemiology. BDV infection can be diagnosed through detecting viral proteins, antibodies and nucleic acid. The fluorescence based quantitative PCR is commonly used for BDV diagnosis because of the superior sensitivity. The assays for detecting plasma BDV specific antibodies include immunofluorescence, Western Blot and ELISA. Western Blot offers comparatively high specificity, which can detect different antibodies on the same blot/strip, and is often used as the confirmatory assay. This study investigated the infection prevalence of BDV in the meadow that raised horses and sheep in northern China. Blood samples were collected from a herd of healthy horses and sheep that were meadow raised in Hailin City, Heilongjiang Province, China. The uncoagulated blood samples were used to isolate peripheral lymphocytes and plasma. We selected Mongolian horses which are stocky, with relatively short but strong legs and a large head. The selected Han sheep is relatively small, has short tail and weighs 35-45 kg on average. BDV p40 mRNA was detected by Taqman based quantitative RT-PCR in lymphocytes of horses and sheep. BDV His-phosphoprotein (P) and His-nucleoprotein (N) fusion proteins were isolated with Histidine coated beads and the purity and immunological activity of the isolated viral proteins were assessed and verified by SDS-PAGE and Western Blot. Plasma BDV antibodies in horses and sheep were detected using the purified fusion proteins as antigens. Quantitative PCR assay showed that 50.00% (16/32) of the tested horse samples were positive for BDV p40 mRNA, and 20.83% (5/24) positive for BDV p40 mRNA in the sheep samples. The purified BDV His-P fusion protein in SDS-PAGE electrophoresis migrated at expected 24 kD size. A known specific BDV P antibody verified the immunogenicity of the purified BDV P in Western Blot, and BDV persistently infected human oligodendrocytes as positive control. The purified BDV His-N fusion protein appeared at the expected 40 kD position and the immunogenicity was also verified. The positive rates of BDV P antibody and N antibody were 11.11% (4/36) and 5.56% (2/36) in the tested horses, respectively. The positive rates of BDV P antibody and N antibody were 13.16% (5/38) and 7.89% (3/38) in the tested sheep, respectively. In conclusion, we utilized the expressed BDV His-P and His-N fusion proteins as antigen and established a modified Western Blot assay for detecting plasma BDV antibodies. Our data showed the direct evidence that natural BDV infection occurred in the meadow raised healthy horses and sheep in northern China.

Clinical Virological and Pathological Investigations on Horses With Neurologic Disorders in Turkey

The aim of this study was to investigate the clinical, pathologic, and viral etiology of horses with neurologic disorders. Twelve English Thoroughbred horses with neurologic disorders were investigated for the presence of neuropathogenic equine herpesvirus-1 (EHV-1) and Borna disease virus (BDV) by real-time polymerase chain reaction (PCR) and histopathological methods. Neuropathogenic EHV-1 was detected in the brain of two horses by real-time PCR. Borna disease virus p24 and p40 gene sequences were detected by real-time RT-PCR in the brain of a 3-year-old horse and in the blood of a 1-year-old horse. High fever, ataxia, depression, lack of coordination, and gait abnormalities were present in these horses, which died within a few days of developing neurologic signs. The BDV p24 and p40 real-time PCR products were sequenced and shown to be identical to previously reported BDV sequences. In the brain of the BDV-positive horse, hyperemia was pronounced in the parenchyma and the meninges. In addition, nonpurulent poliencephalomyelitis characterized by perivascular mononuclear cell infiltration was seen. Mononuclear and polymorphonuclear cell infiltration was also seen in the liver with necrotic perihepatitis besides subacute splenitis and glomerulonephritis and severe hyperemia in the kidney and edema and emphysema in the lung. In conclusion, neuropathogenic EHV-1 and BDV were detected in horses from Turkey using molecular detection methods. Since BDV genetic signatures were detected in Turkey for the first time, future epidemiologic studies need to be performed to investigate the range of host animals, spread, frequency, and molecular diversity of BDV; this will allow to determine the risk of this pathogen for Turkish veterinary and public health.

First Serological Evidence of Borna Disease Virus in Healthy Horses from Yucatan, Mexico

Borna Disease Virus (BDV) causes a progressive non-suppurative meningoencephalitis that sometimes occurs in mortality; this disease has been reported for over two centuries ago in horses, sheep and cats in Central Europe and some regions of Asia. Currently, it is known that it causes neurological symptoms in various species of vertebrates including human beings. In Yucatan, Mexico, there is a single serological report about the circulation of BDV in schizophrenia patients; however, nothing is known about the circulation in animals. We obtained serum samples of 100 horses without apparent clinical signs caused by BDV infection, from various sites in the region. Antibodies against BDV were detected by electrochemiluminescence immunoassay (ECLIA) method with three recombinant proteins: BDV p24, BDV p40 and BDV p10 as antigens; obtaining a high seroprevalence of 44% (44/100). This study generates the first report of the probable activity of the BDV in healthy horses in Mexico and has expanded the infiltration area of BDV in the world. Nevertheless, several molecular investigations are required to detect BDV-RNA circulating and find sequences for clarification of the origin of BDV in Mexican horses.

Evidence for Borna disease virus infection in neuropsychiatric patients in three western China provinces

Borna disease virus (BDV) is a non-cytolytic, neurotropic RNA virus that can infect a wide variety of vertebrate species from birds and primates to humans. Several studies have been carried out to investigate whether BDV is associated with neuropsychiatric diseases. However, this association is still inconclusive. Two panels of subjects consisting of 1,679 various neuropsychiatric patients and healthy people from three western China provinces were enrolled in this study. BDV p24 or p40 RNA in peripheral blood mononuclear cells (PBMCs) were detected in the first panel of 1,481 subjects using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and cerebrospinal fluid (CSF) samples from the BDV RNA-positive individuals were subjected to BDV p24 antibodies testing by enzyme-linked immunosorbent assay (ELISA). BDV p24 or p40 RNA in PBMCs and p24 antibodies in plasma were detected in the second panel of 198 subjects by RT-qPCR and Western blot. A higher prevalence for BDV RNA was demonstrated in patients with viral encephalitis (6.70%), Guillain-Barré syndrome (6.70%), schizophrenia (9.90%) and chronic fatigue syndrome (CFS) (12.70%) compared to healthy controls in the first panel. CSF p24 antibodies were demonstrated in three viral encephalitis patients, two schizophrenia patients and two major depressive disorder (MDD) patients. The prevalences of p24 antibodies in plasma from patients with viral encephalitis (13.24%), multiple sclerosis (25.00%) and Parkinson's disease (22.73%) were significantly higher than healthy controls. This study demonstrates that BDV infection also exists in humans from three western China provinces, and suggests the involvement of the contribution of BDV in the aetiology of Chinese patients with some neuropsychiatric disorders, including viral encephalitis, schizophrenia, CFS, multiple sclerosis and Parkinson's disease.

Research on the association between Borna disease virus infection and the viral encephalitis

To investigate the infection of Borna disease virus (BDV) in unidentified viral encephalitis patients in Ningxia in order to explore if the nucleotide sequence and amino acid sequence in BDV p24 were homophylic with the overseas standard strain. We also intended to investigate the correlation between BDV infection and the unidentified viral encephalitis patients from Ningxia to lay an experimental basis for etiological diagnosis, prevention and treatment on certain human neuropsychiatric disorders. BDV p24 gene fragment was detected by nested reverse transcriptase polymerase chain reaction with fluorescence quantitative PCR (FQ-nRT-PCR) in peripheral blood mononuclear cells (PBMCs). Samples were from 59 unidentified viral encephalitis patients and 60 normal controls. For those positive products, gene sequence and amino acid sequence were then analyzed by BLAST and DNAsist 5.0. The positive rate of the BDV p24 gene fragment in PBMCs from the unidentified viral encephalitis (10.17%) was significantly higher than from the controls (0%) (P < 0.05). Data from the gene sequence on those positive products showed BDV p24 fragment in the patients with unidentified viral encephalitis from Ningxia was homophylic with strain H3915 detected from ill horses (97.67%), as well as with the strain H1766 (96.51%) and strain V (95.35%). However, their amino acid sequences remained the same. BDV infection might probably have existed in the unidentified viral encephalitis patients of Ningxia. The gene sequence seemed to be homophylic with that of standard strain H1766 and strain V, especially with strain H3915.

Epidemiological investigation on natural infection of different canine breeds with Borna disease virus in Ili, China

To investigate the epidemiological pattern of Borna disease virus (BDV) among different canine breeds in Ili, China, and to analyze its potential phylogeny. BDV p24 RNA fragments were detected from peripheral blood mononuclear cells (PBMCs) of canine by modified nested RT-PCR (nRT-PCR). Possible false positives were excluded by determination of both BDV p40 RNA fragments and PMD19 plasmid standards. Analysis were performed on genetic sequence, homologous comparison, amino acid sequence and phylogeny after p24 positive products were validated. BDV p24 RNA fragments were found only in Kazakh Tobet (a shepherd dog) in 8 breeds of 150 cases and their overall positive rate was 11.0% (10/91). Compared with the strain of He/80 from horse and that of S6 from sheep in Germany, the homologous similarities of Kazakh Tobet was 99.2% and 95.7%, and that of amino acid as 100% and 89.3%, respectively. The kinship of Kazakh Tobet was close to He/80 and next to S6. There was potential natural BDV infection in Kazakh Tobet in Ili, and its endemic strain was concerned with He/80 infecting Ili horse and S6 of German Merino sheep introduced into the region from Germany.

Detection and analysis of Borna disease virus in Chinese patients with neurological disorders

Borna disease virus (BDV) is a neurotropic RNA virus that is known to cause neurological disturbances in various animal species, potentially even humans. However, the association between BDV infection and human neurological disorders remains unclear. Between August 2005 and March 2006, 65 patients with neurological disorders were enrolled into our study. The presence of BDV p24 RNA from peripheral blood mononuclear cells (PBMCs) was investigated by using nested reverse transcriptase PCR (RT-PCR) assay. Borna disease virus p24 RNA was detected from PBMCs in six patients with viral encephalitis by using nested RT-PCR assay. However, BDV p24 RNA was not detected in patients with multiple sclerosis or peripheral nerve diseases. There might be possible associations between BDV infection and human viral encephalitis.

Failure to Detect Borna Disease Virus Antibody and RNA from Peripheral Blood Mononuclear Cells of Psychiatric Patients

ObjectiveBorna disease virus (BDV) is a highly neurotropic agent causing various neuropsychiatric symptoms in animals. Over the past two decades, it has been suggested that BDV might be associated with human psychiatric diseases. We aimed to investigate whether BDV is associated with psychiatric patients in Korea.MethodsWe recruited 60 normal controls and 198 psychiatric patients (98 patients with depressive disorder, 60 with schizophrenia, and 40 with bipolar disorder). We used an indirect immunofluorescence antibody (IFA) test for the BDV antibody and a real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assay for p24 and p40 RNA from peripheral blood mononuclear cells (PBMCs).ResultsNeither the BDV antibody nor p24, p40 RNA was detected in controls and patients groups.ConclusionOur results suggest that BDV might not be associated with psychiatric patients in Korea.

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

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. We searched for BDV-derived nucleic acids in blood of race horses and jockeys riding the horses. 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. The p24 and p40 viral nucleic acid sequences were not detected in the PBMC RNAs from any of the race horses or jockeys. These data do not support an epidemiological association between BDV infection, race horses and humans.

Detection of Borna disease virus p24 RNA in peripheral blood cells from Brazilian mood and psychotic disorder patients

Background Borna disease virus (BDV) is a virus that naturally infects a broad range of warm-blooded animals. BDV is an enveloped virus, non-segmented, negative-stranded RNA genome and has an organization characteristic of a member of Bornaviridae in the order of Mononegavirale. In the present work we investigated the presence of BDV p24 RNA in peripheral blood cells from 30 psychiatric patients (19 with mood disorder and 11 with psychotic disorder) and 30 healthy volunteers as the control group. Methods All subjects were interviewed by structured diagnostic criteria categorized according to the DSM-IV, Axis I (SCID-V). The presence of BDV p24 RNA was investigated by nested reverse transcriptase PCR (RT-PCR) using specific primers to p24 from BDV. The specificity of the detection was analyzed by the sequencing of PCR products. Results The mean duration of illness in mood and psychotic patients with p24 RNA of BDV was 25 (± 12.3) years and the median age was 43.77 (± 15.2) years. There were no significant differences in gender and age among patients and control group, neither duration of illness among patients with mood and psychotic disorders in the presence or absence of p24 RNA of BDV. We found a frequency of 33.33% (10/30) of BDV-RNA on patient's group and 13.33% (4/30) on control group. The given sequences revealed identity with GenBank database sequence for BDV. Conclusion The detection of a higher level of BDV-RNA in the peripheral blood cells of patients than on control group should help our understanding of the pathogenesis in the disease.

The humoral and cellular immune response of sheep against Borna disease virus in endemic and non-endemic areas

Borna Disease (BD) is a mostly fatal disease of horses and sheep endemic in central Europe. Antibodies to Borna disease virus (BDV) have been described in sheep and other species living in BD non-endemic areas. Meaningful clinical BDV serology is hampered by difficulties in defining serological cut-offs, which require the investigation of populations from endemic areas. Here we studied BD serology in sheep from endemic and non-endemic areas of similar geography in Switzerland. Antibodies to BDV antigens were detected by ELISA and indirect immunofluorescence analysis (IFA) only in sera from 3 of 6 sheep with autopsy confirmed BD. One serum was positive by IFA but not by ELISA, while 2 sera were negative in both assays, indicating that not all diseased animals develop BDV specific antibodies. Six % of clinically healthy animals (6/106) from an endemic area and 2% from a non-endemic area (4/192) had serum antibody to either BDV p40 or p24 as detected by ELISA. None of the animals showed a cellular immune response to BDV p40. In some healthy sheep from the endemic area, serum antibody titers to BDV p24 antigen remained elevated over several months without onset of disease symptoms. Infections with either BDV or related viruses may thus occur at low frequency in sheep from non-endemic areas leading to the production of antibodies to BDV antigens. We further propose viral strain differences or environmental factor(s) may determine the clinical outcome.

A reverse genetics system for Borna disease virus.

Borna disease virus (BDV) is an enveloped virus. Its non-segmented, negative-stranded RNA genome has the coding capability for six main polypeptides and has an organization characteristic of members of the order 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 establishment of a reverse genetics system for BDV is described. Intracellular synthesis of a BDV RNA analogue or minigenome (MG) from a plasmid was driven by RNA polymerase I. Co-transfection with plasmids expressing the BDV polymerase (L), nucleoprotein (N) and phosphoprotein (P) under the control of RNA polymerase II allowed for BDV MG replication and expression. This process depended on a delicate N:P ratio, whereas the L:P ratio was less critical. Two isoforms of N, Np40 and Np38, are present in BDV-infected cells but only Np40 was strictly required for virus polymerase activity. BDV p10 polypeptide encoded by the P gene exhibited a strong inhibitory effect on BDV MG expression.

Borna disease virus and deficit schizophrenia.

It is controversial whether Borna disease virus (BDV) infects humans and causes psychiatric disorders. The relationship between BDV infection and schizophrenia with deficit syndrome was investigated. Using the Schedule for the Deficit Syndrome, 62 schizophrenic in-patients were selected from three psychiatric hospitals. RNA was extracted from peripheral blood mononuclear cells and analyzed using nested reverse transcriptase-polymerase chain reaction with primers to detect BDV p24 and p40. BDV transcripts were not detected in samples from any of the 62 schizophrenic patients. These data do not support an etiologic association between BDV infection and the deficit form of schizophrenia.

Experimental vertical transmission of Borna disease virus in the mouse.

We demonstrated the experimental vertical transmission of Borna disease virus (BDV) in pregnant BALB/c mice. Giessen strain He/80 of BDV was used in the present study. Six six-week-old mice were inoculated intraperitoneally with 10(5) 50% tissue culture infective doses (TCID50), and were bred immediately. Four pregnant mice were sacrificed under anaesthesia on the 10th and 14th days after vaginal plug formation. Nine newborns from two maternal mice were sacrificed under anaesthesia on the 7th day after birth. Positive signals with RT-nested PCR techniques for BDV p24-RNAs were seen in the fetuses, placentas and brains of all newborn mice. No immunopositivities for BDV p40 were found in the fetuses or placentas at 10 days' gestation. BDV p40 immunopositivities were found in neurons of the fetal brains and in decidual cells of the placentas at 14 days' gestation. They were also found in neurons of the brains of newborn mice. At 10 days' gestation, no positive signals for BDV p40 sense or antisense riboprobes were seen in the fetal brains or placentas. Positive signals were found in neurons of the fetal brains and decidual cells of the placentas at 14 days' gestation. Positive signals for BDV p40 sense and antisense riboprobes were found in almost all neurons throughout the brains of nine newborn mice. These results suggest that persistent infection with BDV in newborn mice may be induced by vertical transmission during gestation.

Two major histocompatibility complex class I-restricted epitopes of the Borna disease virus p10 protein identified by cytotoxic T lymphocytes induced by DNA-based immunization.

Borna disease virus (BDV) infection of Lewis rats is the most studied animal model of Borna disease, an often fatal encephalomyelitis. In this experimental model, BDV-specific CD8(+) cytotoxic T lymphocytes (CTLs) play a prominent role in the immunopathogenesis of infection by the noncytolytic, persistent BDV. Of the six open reading frames of BDV, CTLs to BDV X (p10) and the L-polymerase have never been studied. In this study, we used plasmid immunization to investigate the CTL response to BDV X and N. Plasmid-based immunization was a potent CTL inducer in Lewis rats. Anti-X CTLs were primed by a single injection of the p10 cDNA. Two codominant p10 epitopes, M(1)SSDLRLTLL(10) and T(8)LLELVRRL(16), associated with the RT1.A(l) major histocompatibility complex class I molecules of the Lewis rats, were identified. In addition, immunization with a BDV p40-expressing plasmid confirmed the previously reported RT1.A(l)-restricted A(230)SYAQMTTY(238) peptide as the CTL target for BDV N. In contrast to the CTL responses, plasmid vaccination was a poor inducer of an antibody response to p10. Three injections of a recombinant eukaryotic expression plasmid of BDV p10 were needed to generate a weak anti-p10 immunoglobulin M response. However, the antibody response could be optimized by a protein boost after priming with cDNA.

Persistence of Borna disease virus in naturally infected sheep.

To get an insight into Borna disease virus (BDV) epidemiology, an isolated flock of approximately 25 sheep within the region of Southeast Germany to which the disease is endemic was investigated over a 3-year observation period. BDV-specific antibodies and RNA in peripheral blood mononuclear cells were detected in 12.5 (year 1), 11.5 (year 2), and 19.4% (year 3) and 1.6 (year 1), 0 (year 2), and 14.9% (year 3) of the animals, respectively. BDV persisted in asymptomatic sheep for up to 2 years. Significantly higher numbers of antibody-positive animals were detected seasonally in spring and early summer, the times when usually most of the clinical cases of Borna disease occur. In spring of the third year, numbers of antibody-positive and viral-RNA-positive animals increased significantly despite their having no obvious clinical symptoms. The removal of all antibody- and RNA-positive animals from the flock did not reduce the prevalence of BDV infections in the following year. During a 3-month observation period of three antibody-positive animals, viral RNA was repeatedly detected by reverse transcription-PCR in nasal secretions, saliva, and conjunctival fluids. Sequence analysis revealed clustered nucleotide exchanges among sheep BDV p24 genomes, which differed at five positions from the clustered nucleotide exchanges seen in horse BDV p24 genomes.

Borna Disease in a Dog in Japan

Borna disease (BD) was diagnosed in a 3-year-old male Welsh corgi suffering from a severe and acute progressive disorder of the central nervous system. Histopathologically, neuronal lesions were characterized by a non-suppurative encephalomyelitis dominated by large perivascular cuffs consisting of lymphocytes, macrophages and plasma cells; also present were inflammatory cell infiltrates in the neural parenchyma, neuronophagia and focal gliosis. Strong immunolabelling with BD virus (BDV) p40 antibody was diffusely distributed in the cytoplasm of small and large neurons in areas of the brain with and without inflammatory changes, and also in the spinal cord. Positive hybridization signals with BDV p40 sense and antisense riboprobes were seen in the nucleus and cytoplasm of the neurons throughout the whole brain and spinal cord. BDV p24 RNA in formalin-fixed brain tissue was detected by reverse transcriptase (RT)-nested polymerase chain reaction (PCR). BDV p24 RNA-positive signals were detected in the temporal lobe. This is the first report of spontaneous canine BD in Japan.

Borna disease virus phosphoprotein binds a neurite outgrowth factor, amphoterin/HMG-1.

The Borna disease virus (BDV) p24 phosphoprotein is an abundant protein in BDV-infected cultured cells and animal brains. Therefore, there is a possibility that binding of the p24 protein to cellular factor(s) induces functional alterations of infected neural cells in the brain. To identify a cellular protein(s) that interacts with BDV p24 protein, we performed far-Western blotting with extracts from various cell lines. Using recombinant p24 protein as a probe, we detected a 30-kDa protein in all cell lines examined. Binding between the 30-kDa and BDV p24 proteins was also demonstrated using BDV p24 affinity and ion-exchange chromatography columns. Microsequence analysis of the purified 30-kDa protein revealed that its N terminus showed complete homology with rat amphoterin protein, which is a neurite outgrowth factor abundant in the brain during development. Mammalian two-hybrid and immunoprecipitation analyses also confirmed that amphoterin is a specific target for the p24 protein in vivo. Furthermore, we showed that infection by BDV, as well as purified p24 protein in the medium, significantly decreased cell process outgrowth of cells grown on laminin, indicating the functional inhibition of amphoterin by interaction with the p24 protein. Immunohistochemical analysis revealed decreased levels of amphoterin protein at the leading edges of BDV-infected cells. Moreover, the expression of the receptor for advanced glycation end products, of which the extracellular moiety is a receptor for amphoterin, was not significantly activated in BDV-infected cells during the process of extension, suggesting that the secretion of amphoterin from the cell surface is inhibited by the binding of the p24 protein. These results suggested that BDV infection may cause direct damage in the developing brain by inhibiting the function of amphoterin due to binding by the p24 phosphoprotein.

Identification of the immunodominant H-2K(k)-restricted cytotoxic T-cell epitope in the Borna disease virus nucleoprotein.

Borna disease virus (BDV)-induced immunopathology in mice is most prominent in strains carrying the major histocompatibility complex H-2k allele and is mediated by CD8(+) T cells that are directed against the viral nucleoprotein p40. We now identified the highly conserved octamer peptide TELEISSI, located between amino acid residues 129 and 136 of BDV p40, as a potent H-2K(k)-restricted cytotoxic T-cell (CTL) epitope. When added to the culture medium of L929 target cells, TELEISSI conferred sensitivity to lysis by CTLs isolated from brains of BDV-infected MRL mice with acute neurological disease. Vaccinia virus-mediated expression of a p40 variant with mutations in the two K(k)-specific anchor residues of the TELEISSI peptide (p40(E130K,I136T)) did not sensitize L929 target cells for lysis by BDV-specific CTLs, whereas expression of wild-type p40 did. Furthermore, unlike vaccination with wild-type p40, vaccination of persistently infected symptomless B10.BR mice with p40(E130K,I136T) did not result in central nervous system inflammation and neurological disease. These results demonstrate that TELEISSI is the immunodominant CTL epitope of BDV p40 in H-2k mice.