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DNA ribonucleases that are active against intracellular hepatitis B viral RNA targets
Author(s) -
Asahina Yasuhiro,
Ito Yoshinori,
Wu Catherine H.,
Wu George Y.
Publication year - 1998
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510280236
Subject(s) - ribonuclease , dna , rna , microbiology and biotechnology , biology , hepatitis b virus , nucleotide , intracellular , gene , virology , biochemistry , virus
Abstract DNA ribonucleases directed against direct repeat 1 (DR1) and polyadenylation signal regions of hepatitis B virus (HBV) messages were prepared with phosphorothioate modifications and varying arm lengths. DNA ribonucleases modified throughout the entire molecule and in the target binding arms were completely protected from degradation after incubation with serum. DNA ribonuclease modified only at the 5′ and 3′ termini remained 92.9% intact after incubation. Molecules with no modification were degraded to 67.6% under the same conditions. However, modification of the entire molecule and in the recognition arms resulted in 99.8% and 98.4% inactivation of cleavage activity, respectively. Modification of only the termini resulted in retention of 20% to 40% of original activity. Lengthening each terminally modified arm from 9 to 11 nucleotides increased cleavage efficiency almost 10‐fold. In Huh 7 cells, DR1‐directed DNA ribonucleases with terminal modifications significantly suppressed HBV‐luciferase fusion gene expression up to 48% of control. In contrast, DNA ribonucleases had no effect on a control construct lacking any HBV target sequences. Moreover, inactivated mutant and HCV‐directed DNA ribonucleases had no significant effects on the HBV target. We conclude that resistance of DNA ribonucleases to degradation can be enhanced through phosphorothioate modification. Cleavage activity can be retained by limiting modification to the termini and lengthening the recognition arms. Such DNA ribonucleases can be made to specifically cleave target HBV RNA and substantially inhibit intracellular viral gene expression.