Objective: To study inhibitory effect of antisense oligodeoxynucleotides (asODNs) on genomic HDV ribozyme activity.
Methods: Plasmid pHDVrz277 used to transcribe a 112 nucleotides (nt) genomic HDV ribozyme constructed earlier in our laboratory. It had genomic and antigenomic HDV ribozyme sequences from 665-941nt. The inhibitory effect of five asODNs on genomic HDV ribozyme activity was studied to select the potential effective sequences in vitro.
Results: The results showed that asODN, being complementary to 683-703nt (stem I and self-cleavage site), completely blocked the activity of a 112nt genomic HDV ribozyme transcription in vitro. The inhibition rate of asODNs against 756-770nt (SSrB) and 721-735nt (SSrA) were 69.36% and 48.64% respectively. However, two asODNs covered the 736-750nt (stem IV) and 704-720nt (SSrC) showed almost no inhibitory effect on genomic HDV ribozyme. Fine sequence specificity testing at region 683-703nt revealed that asODN as small as 13 nt flanking the self-cleavage site (683-695nt) retained a high inhibition rate (> 90%).
Conclusion: The results suggested that stem I and SSrB may play an important role in genomic HDV ribozyme and asODNs can block genomic HDV ribozyme activity almost completely.