Patent ID: 8304530

Claim:
An asymmetrical substituted dsRNA silencing agent comprising one or more mismatched base pairs, the dsRNA silencing agent comprising a sense strand and an antisense strand, each strand having a 5′ end and a 3′ end, wherein the one or more mismatched base pairs are within 5 base pairs from the antisense strand 5′ (AS 5′) and the sense strand 3′ (S 3′) end, such that entry of the antisense strand into a RISC complex is promoted relative to the sense strand; such that the antisense strand preferentially guides cleavage of a desired target mRNA by the RISC complex, wherein the asymmetrical substituted dsRNA silencing agent is made by: (a) selecting a first dsRNA silencing agent comprising a sense strand and an antisense strand, each strand having a 5′ and a 3′ end, wherein the first dsRNA silencing agent directs cleavage by a RISC complex at a phosphodiester bond within a desired target mRNA, the first dsRNA silencing agent having a base pairing strength within 5 base pairs from the antisense strand 5′ (AS 5′) and the sense strand 3′ end (S 3′) relative to a base pairing strength within 5 base pairs from the antisense strand 3′ (AS 3′) and the sense strand 5′ end (S 5′), and (b) synthesizing the substituted dsRNA silencing agent comprising one or more substituted base pairs with respect to the first dsRNA silencing agent, wherein the substituted dsRNA silencing agent comprises a sense strand and an antisense strand, each strand having a 5′ and a 3′ end, and wherein the substituted dsRNA silencing agent directs cleavage by the RISC complex at the same phosphodiester bond within the desired target mRNA as the first dsRNA silencing agent, the substituted dsRNA silencing agent having a base pairing strength within 5 base pairs from the AS 5′ and the S 3′ end and a base pairing strength within 5 base pairs from the AS 3′ and the S 5′ end, wherein the one or more substituted base pairs comprise at least one mismatched base pair and are within 5 base pairs from the AS 5′ and the S 3′ end of the substituted dsRNA silencing agent, such that the base pairing strength within 5 base pairs from the AS 5′ and the S 3′ end of the substituted dsRNA silencing agent relative to the base pairing strength within 5 base pairs from the AS 3′ and the S ′5 end of the substituted dsRNA silencing agent is lessened as compared to the base pairing strength within AS 5′ and the S 3′ end of the first dsRNA silencing agent relative to the base pairing strength between the AS3′ and the S 5′ end of the first dsRNA silencing agent.