Ribavirin at concentrations from 1 to 10 micrograms/ml exhibited inhibitory effects on transcription of Borna disease virus (BDV) in persistently infected cells. Our present study indicates that ribavirin is a candidate anti-BDV drug.
Regulation of viral RNA levels in infected cells is considered important in the investigation of viral transcription and replication. Amounts of Borna disease virus (BDV) RNAs were increased in confluent persistently BDV-infected MDCK cells (MDCK/BDV) cells, while maintained at low levels in growing cells. The amount of 1.9-kb RNA without cap formation and polyadenylation at the 5' and 3' ends respectively were remarkably increased (200% per day) in confluent MDCK/BDV cells. Both the full-length genomic and anti-genomic RNAs were increased accompained by 1.9-kb RNA, suggesting the transcription of the 1.9-kb RNA was important for replication of BDV. Ribavirin has an inhibitory effect on replication and transcription of BDV at concentrations from 1 to 10 microgram/ml [Mizutani T et al., Arch Virol (1998)143: 2039-2 044]. BDV transcripts were decreased with ribavirin treatment and increased after its removal which indicated that ribavirin has a reversible inhibitory effect on BDV transcription. Furthermore, BDV transcription was also decreased by two agents, RMNPA and EICAR, which selectively inhibit enzyme activity related to cap formation at the 5' end of mRNA. On the contrary, when the growing MDCK/BDV cells were treated with actinomycin D, transcripts of BDV RNA were increased for 24 h. These agents and culture conditions in this study were found to be useful tools for up-and down-regulation of BDV transcription in persistently BDV-infected cells.
Abstract.Electron heat transport in the low-collisonality ECH plasma is investigated to clarify the effect of neoclassical transport optimization on the thermal plasma transport in LHD. Five configurations are realized by shifting the magnetic axis position in major radius: 3.45m, 3.53m, 3.6m, 3.75m and 3.9m. A clear effective helical ripple (which is a quantitative measure of the neoclassical transport optimization) dependency on the enhancement factor of the global energy confinement relative to ISS95 is observed.Local heat transport analyses show a higher electron temperature and a lower heat transport in the neoclassical transport optimized configuration at half the minor radius. The comparisons of the experimental total heat fluxes with that of the neoclassical transport by DCOM/NNW suggests that the neoclassical transport plays a significant role in the heat transport and that the neoclassical transport optimization is effective in improving the plasma confinement in the low-collisionality LHD plasma.3
ABSTRACT. Transcription of Borna disease virus (BDV) in persistently infected MDCK (MDCK/BDV) cells increased in the fetal bovine serum free media as detected by Northern blot analysis. Especially, the amount of 1.9-kb RNA without cap formation at the 5' end and polyadenylation at the 3' end, increased as compared to other mRNA molecules of BDV. Growth arrest of MDCK/BDV cells observed in the condition of serum starvation might be important for increasing viral transcription. Since N-cadherin is the responsible factor for cellto-cell contact, MDCK/BDV cells were cultured in calcium free medium which inhibits the interaction of N-cadherin. However, inhibition of cell-to-cell contact by N-cadherin is not effective on up regulation of viral transcription. Our finding in this study indicates that enhancement of BDV transcription by serum starvation is a useful technique for further investigation in understanding of mechanisms of BDV transcription.-KEY WORDS: Borna disease virus, serum-starvation, transcription-enhancement.J. Vet. Med. Sci. 61 (7): [831][832][833][834] 1999 Recently, we reported the inhibitory effect of ribavirin on BDV-transcription and replication in persistently BDVinfected cells [9]. On the contrary, the enhancing factors of BDV-transcriptions have to be defined for a clear view of BDV-host cell interaction. Fetal bovine serum (FBS) routinely used for tissue culture is an important factor for cell growth and also for viral multiplication. Cell growth is arrested in the medium without FBS (serum starvation) [1]. In this study, we examined the effect of serum starvation on the BDV transcription in MDCK/BDV cells. Furthermore, we also investigated the possible involvement of cell adhesion on the regulation of BDV transcription.To examine the effect of serum starvation on BDV transcription, growing MDCK/BDV cells in Dulbecco's modified Eagle medium (Nissui) containing 10% FBS were washed with PBS and cultured in FBS-free medium. RNAs were extracted from the cells using ISOGEN (Nippon Gene) at 2, 3, 5 and 7 days. Aliquots of 5 µg of total RNA were fractionated on 1% agarose gel and transferred to nylon membranes, Hybond N+ (Amersham, UK). The prehybridized membranes were then hybridized with RNA
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