Takaaki Nakaya

Demonstration of human Borna disease virus RNA in human peripheral blood mononuclear cells

BDV naturally infects horses and sheep, and causes sporadic neurological disease. Serological evidence suggests an association of BDV, or a related virus, with specific psychiatric diseases in humans. Here, by using a nested RT‐PCR technique, we demonstrate that human BDV RNA is present in the PBMC of psychiatric patients. In an examination of a total of 60 patients from 5 wards of a hospital in Japan, the detection rate differed within each ward, ranging from 8% to > 50% (37% on the average). Of particular note was the finding that the human derived BDV sequences, which included deleted forms in about 23% of the positive samples, were slightly different from those derived from horse BDV. These results suggest urgent consideration of the measures to be taken to cope with the effects of blood transfusion. In addition, the detection of a high level of BDV in the PBMC of patients will help our understanding of the pathogenesis in the disease.

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.

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.

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.

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

Borna disease (BD) is a progressive poliomeningoencephalomyelitis which occurs naturally in horses and sheep. Here, peripheral blood mononuclear cells (PBMC) derived from 57 healthy horses in Japan were examined by a nested reverse transcription-polymerase chain reaction to determine the prevalence of BD virus (BDV) infection. Seventeen (29.8%) of the samples were positive by this examination and the specificity of the amplified product was confirmed by hybridization with authentic oligomer probes. About 60% of the BDV RNA-positive individuals also showed seropositivity by Western blotting. This report is the first for the demonstration of BDV RNA in PBMC of healthy horses, as well as the first on the BDV infection in horses in Japan. Thus, BDV may be more widespread in healthy horses over the world as well as in Japan and the detection of BDV RNA in PBMC at a high rate indicates that the disease might develop in a part of the carriers only after long-incubation period.

Possible correlation between Borna disease virus infection and Japanese patients with chronic fatigue syndrome.

Borna disease virus (BDV) is a neurotropic, as yet unclassified, non‐segmented, negative‐sense, single‐strand RNA virus. Natural infection with this virus has been reported to occur in horses and sheep. In addition, antibodies to BDV in plasma or BDV RNA in peripheral blood mononuclear cells (PBMCs) were also found in patients with neuropsychiatric diseases. We describe here the possible link between the patients with chronic fatigue syndrome (CFS) and infection with BDV.

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.

Higher prevalence of Borna disease virus infection in blood donors living near thoroughbred horse farms

It is believed that Borna disease virus (BDV), an etiological agent of progressive polioencephalomyelitis in horses and sheep, is closely associated with psychiatric disorders in humans since the prevalence of BDV is higher in psychiatric patients than in blood donors. We investigated whether or not BDVs in humans are derived from infected domestic animals, by characterizing the BDVs in blood donors and horses derived from the same region of Hokkaido island, Japan. The seroprevalences (2.6 to 14.8%) of BDV were significantly higher in the blood donors from four regions where most horse farms are concentrated, compared with only 1% in the blood donors from Sapporo, the largest city in Hokkaido. BDV RNA was also detected in peripheral blood mononuclear cells from most of the seropositive horses and blood donors by nested reverse transcriptase‐polymerase chain reaction. These findings support that BDV may be horizontally transmitted, at least in part, from infected horses to humans. J. Med. Virol. 52:330–335, 1997.

Clinical investigation of the relationship between Borna disease virus (BDV) infection and schizophrenia in 67 patients in Japan

The relationship between Borna disease virus (BDV) infection and schizophrenia in the clinical time course was investigated. By nested reverse‐transcribed polymerase chain reaction (RT‐PCR) and Western blotting, BDV‐specific RNA and anti‐BDV antibodies were examined in the EDTA‐treated blood from 67 schizophrenic patients (according to DSM‐III‐R) in Japan. A significantly higher proportion (45%) of anti‐BDV antibody and/ or BDV RNA carriers were found among these 67 schizophrenic patients than in 26 controls (0%). There were no apparent associations of BDV infection with age, age at onset, period of hospitalization, accompanying somatic diseases, a past history of tuberculosis, a history of transfusion, a family history, or doses of psychotropic drugs. It is possible that, at least, BDV infection in schizophrenic patients may not be a nosocomial (hospital‐acquired) infection, although the route of BDV infection in humans remains unidentified. More studies on the relationship between BDV infection and clinical psychosomatic features should be performed in order to elucidate the pathogenesis of schizophrenia.

Borna disease virus RNA in peripheral blood mononuclear cells obtained from healthy dairy cattle

Abstract We examined natural infection of Borna disease virus (BDV) in 74 healthy dairy cattle in Japan. The seroprevalence determined using recombinant BDV p24 protein was 20.3%. The prevalence of BDV RNA in peripheral blood mononuclear cells (PBMCs) determined by polymerase chain reaction for p24 was 10.8%. Cell fraction of the PBMCs revealed the presence of BDV RNA in the T cell-enriched fraction. Thus, BDV infection is wide-spread even among healthy cattle.