OBJECTIVETo investigate the in vivo functional roles of the La autoantigen (La), the human homologue of the 33-kDa vesicle-associated membrane protein-associated protein (hVAP-33), and the subunit gamma of the human eukaryotic initiation factors 2B (eIF2Bgamma) as co-infection factors supporting chronic infection with hepatitis C virus (HCV).

METHODSSmall interfering (si)RNAs were designed against the HCV internal ribosome entry site (IRES) and transfected into Huh7 cells chronically infected with the HCV pseudovirus (designated as Huh7-HCV cells). The IRES siRNA producing the most effective silencing was selected for further analysis by fluorescence quantitative polymerase chain reaction (qPCR). siRNAs designed against La, hVAP-33, and eIF2Bgamma and the IRES-specific siRNA were then transfected, respectively or in various combinations, into the Huh7-HCV cell line for 48 h. The delta CT values were calculated and used to compare the HCV inhibitive efficacies of the siRNAs in isolation or in combination. Western blotting analysis was used to compare the quantity of core protein expression in each group.

RESULTSThe four gene-specific siRNAs, in isolation or in combination, caused inhibition of HCV replication and gene and protein expressions to varying degrees. The combination of La + IRES siRNAs produced the strongest inhibition of HCV core antigen expression. The combinations of hVAP-33 + IRES siRNAs and eIF2Bgamma + IRES siRNAs produced stronger inhibitions of HCV replication and gene and protein expressions than either hVAP-33 siRNA or eIF2Bgamma siRNA alone.

CONCLUSIONLa, hVAP-33, and eIF2Bgamma act as co-infection factors of HCV chronic infection in vivo. HCV replication and gene and protein expression can be inhibited significantly by RNA interference of these co-infection factors and/or HCV IRES.