The purpose of the current study is to investigate the anti-IFN-αeffects and to determine the functional region of the novel protein TS′X′encoded by the 3022-1787nt deletion mutant of hepatitis B virus ( HBV) . Regions coding for TS′X′( in frame with the opening reading frame of DNA polymerase, in which T stands for terminal protein, S′for partially deleted spacer region, and X′for truncated X protein) and TS′( N-terminal of TS′X′containing terminal protein and partially deleted spacer region) were amplified by PCR and cloned into the pcDNA3. 1/HisC vector separately. The recombinant vector was transfected into Huh7 hepatocytes individually by FuGENE6 transfection reagent, and the expression of the fusion protein was verified by Western blot analysis. The recombinant or empty vector was co-transfected to Huh7 hepatocytes with IFN-α response reporter plasmid p6-16CAT at the molar ratio of 5∶1, 10∶1,15∶1 and 30∶1, and cells were treated with IFN-α2a ( 100 IU/ml) 48 h post-transfection. After 24 h of stimulation, the cells were lysed and the intracellular CAT value was calculated by ELISA assay. The results demonstrated that, as compared to the empty vector, the intracellular CAT values were gradually reduced in parallel with an increasing amount of TS′X′or TS′recombinant ( n = 6, P < 0. 05) , while no significant differences were observed between TS′X′and TS′recombinants ( n = 6, P > 0. 05) . It was concluded that the novel protein TS′X′ encoded by the 3022-1787nt deletion mutant of HBV suppressed the response of Huh7 hepatocytes to IFN-α, and the N- terminal region was a functional domain for its anti-IFN-α effects.
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