Abstract: A screening method for a compound which inhibits a ribonuclease H activity of a reverse transcriptase which includes incubating a substrate with an appropriate primer hybridized to an appropriate template, a metal ion and a reverse transcriptase to form a complex, adding a test substance, and after these steps adding dNTPs to initiate DNA synthesis, measuring the amount of nucleic acid cleaved from the template, and comparing the measured value with a measured value in the absence of a test substance.

Abstract: By using Template: 5?-NRWXZ-3? Primer: 3?-Y-5? (wherein, Y hybridizes to X of a template, N is 13-19 mer DNA, RNA or a chimeric nucleic acid, R is RNA, W is DNA or a chimeric nucleic acid, X is 15 mer or more DNA, RNA or a chimeric nucleic acid, Y is a same length DNA, RNA or a chimeric nucleic acid with X to which Y hybridizes. In case that X to which Y hybridizes is DNA, Y is DNA. In case that X to which Y hybridizes is RNA, Y is RNA. In case that X to which Y hybridizes is a chimeric nucleic acid, Y is a chimeric nucleic acid (In the chimeric nucleic acid, in case that X to which Y hybridizes is DNA, Y is DNA. In case that X to which Y hybridizes is RNA, Y is RNA), Z is DNA, RNA or a chimeric nucleic acid (provided that, W and Z can be absent)), a test compound can be preincubated with a reverse transcriptase-substrate complex formed under the presence of a metal ion and a screening method for a substance which inhibits polymerization-dependent RNase H activity is established.