Abstract
Serious outbreaks of severe acute respiratory syndrome (SARS), caused by the newly discovered coronavirus SARS-CoV, occurred between late 2002 and early 2003. RNA interference (RNAi) is a process by which the introduced small interfering RNA (siRNA) could bind to the homologous RNA sequence and the binding adduct is degraded by RISC complex. Recently, siRNA- induced RNA interference may provide a new approach for the therapy of pathogenic or genetic diseases. The plasmid C1+ SARS 1000, which contains the genes encoding eGFP and part of SARS-Cov S protein, was co-transfected with plasmid expressing specific siRNAs for SARS-Cov S gene in HeLa cells. Among 4 siRNA sequences, we found that one siRNA, name IIIsas, could specifically reduce the expression of spike mRNA over 80% detected by Northern bloting, reverse transcription PCR and quantitative PCR. The downregulation of SARS-S gene expression was correlated with the concentrations of the siRNA expression vector employed in a range of 4.5~18 □g plasmid DNA. The siRNA was delivered by adenoviral vector to overcome the low transfection efficiency of plasmid DNA. The results showed that the expression of SARS-spike protein gene was markedly reduced to 6%. Our studies demonstrate the feasibility of using adenoviral vector to deliver and express the siRNA of specific gene for the therapy of viral infection and other diseases in future.