In vitro inhibition of the hepatitis delta virus replication mediated by interferon and trans-ribozyme or antisense probes

Background/Aims: In this study, the inhibition of hepatitis delta virus replication mediated by trans-ribozyme and antisense probes, alone or in combination with recombinant interferon alpha-2a, has been assayed. Methods: A 60-nucleotide-long designed trans-ribozyme, which contains the catalytic core of the hammerhead ribozyme, and a 163-nucleotide-long antisense probe were directed against the same region of the viral genome in in vitro and cell culture systems. Results: The ribozyme activity, assayed in a chemically isolated system, resulted in the trans-cleavage of 10–20% of the 40-nucleotide-long RNA substrate. A 5-nucleotide deletion in one of the flanking arms, obtained by random mutagenesis, resulted in enhancement of the trans-cleavage activity in as many as 40–60% of the substrate molecules. The efficiency of the optimized trans-ribozyme and antisense probes against the complete viral genome was assayed in a cell culture system. The inhibitory efficacy (25%) of the trans-ribozyme is lower than that of the antisense probe (35%) or interferon at 1000 U/ml (47%). An enhancement of the interferon efficacy was achieved when it was administered in cells having a previous basal expression of ribozyme (70%) or antisense probes (83%). Conclusions: These results suggest that the combination of ribozyme or antisense probes with interferon could be a promising approach to the treatment of RNA virus infections.