Acquisition of Borna disease virus virulence by in vivo evolution

博尔纳病病毒(Borna Disease Virus，BDV)是一种嗜神经性包膜病毒，基因组为非节段性、单链和负链RNA。我们已经报道了BDV在日本动物中的分布，如马、羊、牛和猫。此外，我们已经报道，与献血者相比，精神分裂症和慢性疲劳综合征患者的BDV患病率显著更高。在本研究中，我们对人脑中可能存在的一种BDV毒株进行了鉴定，并获得了以下结果：1)在4例精神分裂症患者尸检脑组织中检测到1例脑海马、脑桥和小脑中的BDV RNA。2)从BDV RNA阳性的海马区和小脑中分离出人BDV，将这些脑区接种到新生沙土鼠脑中，然后与人少突胶质瘤来源的细胞系共培养。3)测定了一例精神分裂症患者脑源性BDV的全长核苷酸序列，并与马脑源性BDV进行了比较，人BDV与马BDV在核苷酸水平上的同源性约为98%。尤其是磷蛋白(P24)和糖蛋白(Gp 56)具有较多的氨基酸取代。4)我们检测了帕金森病患者黑质中BDV RNA的可能检测结果。在A医院的4只和B医院的5只沙土鼠中，分别有3只和3只BDV RNA阳性，新生沙土鼠脑内接种BDV RNA阳性的黑质也有BDV RNA阳性。然而，尽管我们在与从精神分裂症患者的脑中分离出BDV相同的条件下进行了检测，但我们无法在人少突胶质瘤来源的细胞系中检测到BDV的复制。

Borna disease virus (BDV) is neurotropic envelope virus with nonsegmented, single-stranded and minus-stranded RNA as a genome. We have reported that BDV is distributed in Japanese animals such as horses, sheep, cattle and cats. Further, we have reported that BDV prevalence was significantly higher in patients with schizophrenia and chronic fatigue syndrome, compared with blood donors. In this study, we have worked on the possible identification of a virulent BDV in human brains and obtained results as follows :1) We detected BDV RNA in hippocampus, pons and cerebellum in one among four autopsied brains derived from schizophrenia patients. In contrast, there are no positive cases in several brain regions examined which were derived from 2 autopsied healthy brains.2) We isolated human BDV from BDV RNA-positive hippocampus and cerebellum by inoculation of these brain regions to newborn gerbils followed by co-culture of the gerbil brain with human oligodendroglioma-derived cell line. 3) Full-length nucleotide sequence of BDV derived from the brain of a patient with schizophrenia was determined and compared with that of horse brain-derived BDV.The homology of human BDV with horse BDV at nucleotide sequence level was about 98%. Especially, the phosphoprotein (p24) and glycoprotein (gp 56) had many ammo acid substitutions. 4) We have examined the possible detection of BDV RNA in substantia nigra from patients with Parkinson's disease. Three among four from A hospital and three among 5 from B hospital were positive for BDV RNA BDV RNA was also positive in newborn gerbils intracranially inoculated with these BDV RNA-positive substantia nigras. However, we could not detect BDV replication in human oligodendroglioma-derived cell line, although we examined under the same conditions as in BDV isolation from the brain of a patient with schizophrenia.