A Potential Therapeutic for Pandemic Influenza Using RNA Interference

RNA interference (RNAi) involves sequence-specific downregulation of target genes, leading to gene silencing in vitro and in vivo. Synthetic small interfering RNAs (siRNAs), formulated with appropriate delivery agents, can serve as effective tools for RNAi-based therapeutics. The potential of siRNA to provide antiviral activity has been studied extensively in many respiratory viruses, including influenza virus, wherein specific siRNAs target highly-conserved regions of influenza viral genome, leading to potent inhibition of viral RNA replication. Despite various delivery strategies, such as polycations and liposomes that have been employed to formulate siRNAs, effective delivery modalities are still needed. Although current strategies can provide significant biodistribution and delivery into lungs allowing gene silencing, complete protection and prolonged survival rates against multiple strains of influenza virus still remains a key challenge. Here, we describe methods and procedures pertaining to screening and selection of highly effective influenza-specific siRNAs in cell culture, in mice, and in the ferret model. This will be potentially useful to evaluate RNAi as a therapeutic modality for future clinical application.