The invention relates to double-stranded ribonucleic acids (dsRNAs) targeting gene expression of phosphatidylinositol 4-kinase (PI4K), in particular human phosphatidylinositol 4-kinase, catalytic, beta polypeptide (PIK4CB) or human phosphatidylinositol 4-kinase, catalytic, alpha polypeptide (PIK4CA), and their use for treating infection by positive stranded RNA viruses such as hepatitis C virus (HCV). Each dsRNA comprises an antisense strand having a nucleotide sequence which is less that 30 nucleotides in length, generally 19-25 nucleotides in length, and which is substantially complementary to at least a part of the PIK4CB or PIK4CA target mRNA. A plurality of such dsRNA may be employed to provide therapeutic benefit. The invention also relates to a pharmaceutical composition comprising the dsRNA together with a pharmaceutically acceptable carrier, and including a delivery modality such as fully encapsulated liposomes or lipid complexes. The invention further includes methods for treating diseases caused by positive stranded RNA virus infection using the pharmaceutical compositions; and methods for inhibiting the propogation of positive stranded RNA viruses in and between cells.