| Co-Investigator(Kenkyū-buntansha) |
TANAKA Shinya Hokkaido Univ., Grad.School.of Med., Lecturer, 大学院・医学研究科, 講師 (70261287)
SAWA Hirofumi Hokkaido Univ., Grad.School.of Med., Asso.Pro, 大学院・医学研究科, 助教授 (30292006)
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| Research Abstract |
JC virus (JCV) causes in humans a demyelinating disease, progressive multifocal leukoencephalopathy (PML), but mechanisms of demyelination by JCV remain unknown.
To investigate early events of JCV infection including attachment, penetration, and transport to the nuclei where viral replication occurs, we have analyzed the susceptibility of 15 different cell lines to infection using a semi-quantitative PCR assay, ISH, laser scanning confocal microscopy and a viral replication assay. JCV entry was observed in all cell lines within 10 min after inoculation. Inhibition of viral entry both by an anti-JCV VP1 antibody and sialidase treatment to remove sialic acid residues argues in favor that JCV VP1 functions as ligand and that JCV receptor is the cellular surface molecules containing sialic acids. In addition, chlorpromazine, a clathrin-dependent pathway inhibitor, significantly suppressed entry of JCV into nuclei, suggesting that JCV utilizes a clathrin pathway during the entry to cells. Fr
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om these observations it has been proved that JCV receptor is broadly expressed in the cells originated from various tissues and species.
Because the recent clinicopathological analyses have disclosed that human T-lymphotropic virus type I (HTLV-I) could be an underlying disease of PML, we have examined whether the HTLV-I encoded regulatory protein Tax activates JCV transcription. Using a dual luciferase assay and an electrophoretic mobility shift assay (EMSA), we found the expression of HTLV-I Tax activated the transcriptional potential of both early and late promoters of JCV in human neural cells in a NF-κB-dependent manner. In addition, we demonstrated the presence of Tax-bound protein(s) which were specifically present in non-neural cells.
We also found that agnoprotein, one of the JCV late proteins, enhanced the JCV promoter itself. These results make it possible to establish an effective therapy against PML based on the mechanism of viral infection and multiplication in the neural cells. Less
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