Modified small interfering rna molecules and methods of use

Abstract

The present invention provides double-stranded RNA molecules that mediate RNA interference in target cells, preferably hepatic cells. The invention also provides double-stranded RNA (dsRNA) molecules that are modified to be resistant to nuclease degradation, which inactivates a virus, and more specifically, hepatitis C virus (HCV). The invention also provides a method of using these modified RNA molecules to inactivate virus in mammalian cells and a method of making modified small interfering RNAs (siRNAs) using human Dicer. The invention provides modified RNA molecules that are modified to include a dsRNA or siRNA wherein one or more of the pyrimidines in the RNA molecule are modified to include 2′-Fluorine. The invention also provides dsRNA or siRNA in which all pyrimidines are modified to include a 2′-Fluorine. The invention provides that the 2′-Fluorine dsRNA or siRNA molecule is further modified to include a two base deoxynucleotide “TT” sequence at the 3′ end of the molecule.

What is claimed is: 
     
         1 . A method for inactivating Hepatitis C Virus (HCV) in a patient, the method comprising the step of administering to said patient a siRNA in an amount effective to inactivate said virus, wherein said siRNA comprises a first strand and a second strand, wherein the sequence of said first strand is SEQ ID NO: 46 and the sequence of said second strand is selected from the group of SEQ ID NO: 18 and SEQ ID NO: 45. 
     
     
         2 . The method of  claim 1 , wherein the siRNA comprises at least one modification at the 2′ position of at least one ribonucleotide. 
     
     
         3 . The method of  claim 1 , wherein said siRNA comprises at least one modification selected from the group consisting of fluoro-, methyl-, methoxyethyl- and propylmodification. 
     
     
         4 . The method of  claim 3 , wherein said fluoro-modification is a 2′ fluoromodification or a 2′,2′-fluoro-modification. 
     
     
         5 . The method of  claim 1 , wherein at least one pyrimidine of said siRNA is modified. 
     
     
         6 . The method of  claim 1 , wherein both strands of said siRNA contain at least one modified nucleotide.