title: Persistent borna disease virus infection confers instability of HSP70 mRNA in glial cells during heat stress.
abstract: Borna disease virus (BDV) is a highly neurotropic RNA virus that causes neurological disorders in many vertebrate species. Although BDV readily establishes lasting persistence, persistently infected cells maintain an apparently normal cell phenotype in terms of morphology, viability, and proliferation. In this study, to understand the regulation of stress responses in BDV infection, we investigated the expression of heat shock proteins (HSPs) in glial cells persistently infected with BDV. Interestingly, we found that BDV persistence did not upregulate HSP70 expression even in cells treated with heat stress. Furthermore, BDV-infected glial cells exhibited rapid rounding and detachment from the culture plate under various stressful conditions. Immunofluorescence analysis demonstrated that heat stress rapidly disrupts the cell cytoskeleton only in persistently infected cells, suggesting a lack of thermotolerance. Intriguingly, we found that although persistently infected glial cells expressed HSP70 mRNA after heat stress, its expression rapidly disappeared during the recovery period. These observations indicated that persistent BDV infection may affect the stability of HSP70 mRNA. Finally, we found that the double-stranded RNA-dependent protein kinase (PKR) is expressed at a constant level in persistently infected cells with or without heat shock. Considering the interrelationship between HSP70 and PKR production, our data suggest that BDV infection disturbs the cellular stress responses to abolish antiviral activities and maintain persistence.
authors.affiliation: Department of Virology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita Osaka 565-0871, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Yamashita
authors.forename: Wataru
authors.initials: W
authors.lastname: Kamitani
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yanai
authors.forename: Naohiro
authors.initials: N
authors.lastname: Ohtaki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Byeong-Jae
authors.initials: BJ
authors.lastname: Lee
authors.forename: Shoutaro
authors.initials: S
authors.lastname: Tsuji
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ikuta
authors.forename: Keizo
authors.initials: K
authors.lastname: Tomonaga
mesh_terms: D000818:Animals; D001890:Borna Disease / Q000378:metabolism* / Q000473:pathology; D001891:Borna disease virus; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006358:Hot Temperature; D009457:Neuroglia / Q000166:cytology / Q000821:virology*; D011494:Protein Kinases / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013312:Stress, Physiological / Q000378:metabolism*; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D018840:HSP70 Heat-Shock Proteins; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D011494:Protein Kinases