Watanabe Yohei, Ibrahim Madiha S, Hagiwara Katsuro, Okamoto Minoru, Kamitani Wataru, Yanai Hideyuki, Ohtaki Naohiro, Hayashi Yohei, Taniyama Hiroyuki, Ikuta Kazuyoshi, Tomonaga Keizo
Department of Virology, Research Institute for Microbial Diseases (BIKEN), Osaka University, Suita, Osaka 565-0871, Japan.
Microbes Infect. 2007 Apr;9(4):417-27. doi: 10.1016/j.micinf.2006.12.015. Epub 2007 Jan 12.
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.
为了研究博尔纳病病毒（BDV）野外分离株的生物学特性，以及了解非流行国家之外的BDV感染情况，我们从日本一头患有博尔纳病的小母牛的脑样本中分离出了该病毒。我们证明脑裂解物中含有BDV的复制产物，并能在大鼠胶质瘤细胞中诱导病毒增殖，这表明牛脑中存在具有复制能力的BDV。这种BDV野外毒株名为Bo/04w，与实验室适应的BDV毒株相比，显示出高效的病毒释放和传播能力，并且在感染过程中病毒磷蛋白（P）也呈现出独特的表达模式。有趣的是，我们发现感染Bo/04w的细胞中P水平显著较低，并且该分离株的转录比BDV实验室毒株更高效。这些结果表明，野外分离株可能在感染细胞中将P的表达调节到最佳水平。我们还证实Bo/04w在新生沙鼠脑中保持生物学活性。测序结果显示，尽管存在生物学差异，但该野外分离株在基因上与BDV实验室毒株密切相关。我们在此讨论来自流行国家和非流行国家的BDV分离株之间的序列相似性。
