title: ISG15 over-expression inhibits replication of the Japanese encephalitis virus in human medulloblastoma cells.
abstract: IFN-stimulated gene 15 (ISG15), an ubiquitin-like protein, is rapidly induced by IFN-alpha/beta, and ISG15 conjugation is associated with the antiviral immune response. Japanese encephalitis virus (JEV), a mosquito-borne neurotropic flavivirus, causes severe central nervous system diseases. We investigated the potential anti-JEV effect of ISG15 over-expression. ISG15 over-expression in human medulloblastoma cells significantly reduced the JEV-induced cytopathic effect and inhibited JEV replication by reducing the viral titers and genomes (p<0.05, Student's t-test); it also increased activation of the interferon stimulatory response element (ISRE)-luciferase cis-acting reporter in JEV-infected cells (p<0.05, Chi-square test). Furthermore, Western blotting revealed that ISG15 over-expression increased phosphorylation of IRF-3 (Ser396), JAK2 (Tyr1007/1008) and STAT1 (Tyr701 and Ser727) in JEV-infected cells (P<0.05, Chi-square test). Confocal imaging indicated that nucleus translocation of transcription factor STAT1 occurred in ISG15-over-expressing cells but not in vector control cells post-JEV infection. ISG15 over-expression activated the expression of STAT1-dependent genes including IRF-3, IFN-beta, IL-8, PKR and OAS before and post-JEV infection (p=0.063, Student's t-test). The results enabled elucidation of the molecular mechanism of ISG15 over-expression against JEV, which will be useful for developing a novel treatment to combat JEV infection.
authors.affiliation: Institute of Biotechnology, National Changhua University of Education, Changhua 500, Taiwan.
authors.forename: Nai-Wan
authors.initials: NW
authors.lastname: Hsiao
authors.forename: Jiun-Wei
authors.initials: JW
authors.lastname: Chen
authors.forename: Tsuey-Ching
authors.initials: TC
authors.lastname: Yang
authors.forename: Gregg M
authors.initials: GM
authors.lastname: Orloff
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Chih-Ho
authors.initials: CH
authors.lastname: Lai
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Lan
authors.forename: Cheng-Wen
authors.initials: CW
authors.lastname: Lin
mesh_terms: D045744:Cell Line, Tumor; D016207:Cytokines / Q000096:biosynthesis* / Q000276:immunology*; D003588:Cytopathogenic Effect, Viral; D004664:Encephalitis Virus, Japanese / Q000254:growth & development* / Q000276:immunology*; D015870:Gene Expression; D006801:Humans; D008527:Medulloblastoma / Q000821:virology*; D015398:Signal Transduction; D014452:Ubiquitins / Q000096:biosynthesis* / Q000276:immunology*; D019562:Viral Load
chemical_list: D016207:Cytokines; D014452:Ubiquitins; C074034:ISG15 protein, human