Efficient site-specific nonribozyme opening of hepatitis delta virus genomic RNA in infected livers.

Examination of the 1,679-nucleotide (nt) unit-length hepatitis delta virus (HDV) RNAs in the livers of two HDV-infected woodchucks showed that 96% of the antigenomic RNA but only 50% of the genomic RNA was circular. We subsequently found that at least half of the linear unit-length genomic RNA was open at a unique location. Using a modified form of RNA ligation-mediated amplification of cDNA ends, we showed that the 5' end was located at nt 1212. Like the previously described ribozyme cleavage site at nt 686, the new site produced a 5'-OH. Nevertheless, we showed that this novel site was not produced by activity of the HDV genomic ribozyme. We speculate that the 5' end at nt 1212 reflects a preferred site of posttranscriptional endonucleolytic cleavage of genomic RNA.