RNA interference and antiviral therapy

Table 2 Strategies designed to inhibit HCV replication via RNA interference

Target gene	RNAi inducer (length)	Promoter	Vector	Model	Delivery methods	Inhib. of virus prod. (fold)	Reference
In vitro studies
Viral gene
5’-UTR	siRNA (21 bp)	-	-	5-2 cells (Huh-7)	Transfection	-6	[79]
	siRNA (21 bp)/shRNA(19 bp)1	U6	Plasmid	293T, Huh 7	Transfection	> 10	[78]
NS4B	siRNA (23 bp)	-	-	Huh-7.5	Transfection	-80	[80]
NS3, NS4B, NS5A, NS5B	siRNA (21 bp)	-	-	S1179I (Huh-7)	Transfection	-23	[81]
IRES, NS3, NS5B	siRNA (23bp)/shRNA (21 bp)2	Dual H1	Plasmid	Huh-7	Transfection	> 9	[82]
5’-UTR, C, NS4B, NS5A, NS5B	esiRNA (15-40 bp)3/shRNA (19bp)	H1	Mo-MuLV	Huh-7	Transfection / Transduction	-100	[88]
5’-UTR, C, NS3, NS5B	siRNA (21 bp)/shRNA (19 bp)4	U6	Plasmid/Lentivirus	Huh-7	Transfection / Transduction	-7	[83]
Cellular gene
Lα, PTB, eIF2Bγ, hVAP33	shRNA (19 bp)	U6	Plasmid/Adenovirus	Huh-7	Transfection / Transduction	-13	[91]
Cyp-A,B,C	shRNA (NR)	U6	Plasmid/Retrovirus	Huh-7	Transfection / Transduction	-10	[92]
Combination of viral and cellular genes
5’-UTR, 3’-UTR, PSMA7, HuR	shRNA (19-21 bp)	U6	Plasmid/Retrovirus	Huh-7	Transfection / Transduction	> 2	[89]
CD81, IRES, NS5B	shRNA (19-21 bp)	H1	Lentivirus	Huh-7	Transduction	> 32	[90]
In vivo studies
NS5B	siRNA (23 bp)	-	-	Mice	Hydrodynamic transfection	3	[84]
IRES	shRNA (19-25 bp)5	-	-	Mice	Hydrodynamic transfection	-50	[85]

The fold inhibition of virus production represents the most potent effect caused by a specific siRNA or combinatorial siRNAs. All siRNAs were prepared by chemical synthesis unless indicated otherwise. UTR: Untranslated region; NS: Non-structural; IRES: Internal ribosomal entry site; C: Core protein; esiRNA: Endoribonuclease-prepared siRNA; Mo-MuLV: Moloney murine leukemia virus; PTB: Polypyrimidine tract-binding protein; eIF2Bγ: Subunit gamma of human eukaryotic initiation factors 2B; hVAP-33: Human VAMP-associated protein of 33 kDa; Cyp: Cyclophilin; PSMA7: Proteasome a-subunit 7; HuR: Hu antigen R; N.R: not reported.

¹stem-loop- and tandem-type siRNA expressed from DNA-based vectors driven by one and two U6 promoters respectively.

²shRNA expressed from a transfected plasmid under the control of two H1 tandem promoters that drive the synthesis of each of the siRNA strand.

³esiRNA generated by in vitro T3/T7 promoter-mediated transcription.

⁴shRNA expressed from a transfected plasmid or a lentivirus vector respectively under the control of a U6 promoter. 5 shRNA generated by in vitro T7 promoter-mediated transcription.