| Summary: | 碩士 === 國立臺灣大學 === 微生物學研究所 === 85 ===
Hepatitis C virus (HCV) is the major causative agent of transflision-associated non-A, non-B hepatitis. HCV infection often results in chronic hepatitis and progresses to hepatocellular carcinoma. HCV is an enveloped virus. Its genome contains a positive single stranded RNA of approximatehly 9.5 kb and encodes a large polyprotein precursor about 3000 amino acids, which is cleaved by both cellular and viral proteases into multiple proteins. The core protein of hepatitis C virus is generated from the amiao-terminus of the polyprotein precursor by the cleavage of cellular signal peptidase.
HCV core protein is a structure protein that is associated with viral RNA genome to form viral nucleocapsid. The core protein can form multimeric complexes and has three independent nuclear localization signals. Recent studies have indicated that phosphorylated HCV core protein can inhibit the replication and expression of hepatitis B viral genome. In addition core protein cooperates with ras and transforms primary rat embryo fibroblasts to tumorigenic phenotype. Therefore HCV core protein is a multifunctional protein and may be associated with the pathogenesis of human hepatocellular carcinoma.
In this study, expression systems for the core protein are first established. An expression plasmid that encodes HCV core protein with C-terminal 18 amino acids deleted is constructed. Using the recombinant vaccinia virus-T7 RNA polymerase expression system, cellular localization of the full length and C-terminal truncated core proteins and their effects on the expression of c-myc gene are determined. Results demonstrate that both the full-length and truncated core proteins generated from the recombinant vaccinia virus expression system can suppress the expression of c-myc gene. On the other hand, the full length core protein expressed under general transfection condition slightly transactivates c-myc gene, whereas the C-terminal truncated core protein has a little suppressive effect.
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