Treatment of influenza

A double-stranded RNA which inhibits replication of Influenza B viruses by RNA interference, wherein the double-stranded RNA consists of an RNA and an antisense RNA thereof, wherein the RNA is RNA of nucleotide sequence as set forth in SEQ ID NO:10 or RNA of nucleotide sequence as set forth in SEQ ID NO:10 in which 1 to 3 nucleotide(s) is/are substituted, and wherein DNA or RNA of 1 to 4 nucleotide(s) are attached to 3′ends of the sense and the antisense strands of a double-stranded RNA to form overhanging ends.

A hairpin RNA which forms the double-stranded RNA in a cell, which inhibits replication of Influenza B viruses by RNA interference, wherein the double-stranded RNA consists of an RNA and an antisense RNA thereof, each of which is 19-25 nucleotides in length, wherein the RNA comprises RNA of nucleotide sequences set forth in SEQ ID NO:10 or RNA of nucleotide sequence as set forth in SEQ ID NO:10 in which 1 to 3 nucleotide(s) is/are substituted, and wherein the RNA is linked to the antisense RNA thereof by a linker sequence.