[Effect of structural domain II of HCV 5' noncoding region on its translation initiation activity]

To examine the role of domain II of hepatitis C virus (HCV) 5' noncoding region (5' NCR) in its translation initiation activity.

The fragment of HCV 5' NCR with deletions of 5'-proximal 118 nucleotides were amplified with PCR, then was used to substitute for the full length HCV 5' NCR of plasmid pCMVNCRluc, a firefly luciferase (Fluc) eukaryotic expression plasmid regulated by HCV 5' NCR, to generate recombinant plasmid pCNl-d3. pCMVNCRluc, pCNl-d2 (modified pCMVNCRluc with deletions of HCV 5' NCR ntl-43) and pCNl-d3 were transfected into HepG2 cells with liposome transfection protocol, respectively, and the relative luciferase activity was measured to analyze the regulatory effect of the truncated 5'NCR on Flue gene expression. Meanwhile the Flue mRNA levels were detected by RT-PCR.

The recombinant plasmid was successfully constructed. The Flue mRNA levels of the 3 plasmids were not significantly different (P > 0.05), and there were also no significant difference between the relative luciferase activity of plasmids pCNl-d2 and pCMVNCRluc (P > 0.05). However, that of pCNl-d3 was decreased significantly (P < 0.01, compared with pCNl-d2 or pCMVNCRluc).

Structural domain II of HCV 5' NCR plays an important role in its translation initiation activity.