SiRNAs

VEGF inhibitors Humanized neutralizing antibodies, antisense oligonucleotides, siRNA, aptamers... 

Dicer represents the key enzyme in the RNAi pathway. Dicer is also known as Helicase with RNAse motif, heRNA, Helicase-moi, K12H4.8-like, or KIAA0928. Dicer produces cleaves long double-stranded RNA into small pieces of about 21-23 nucleotides. These so-called siRNA duplexes produced by the action of Dicer contain 5 -phosphates and free 3 -hydroxylgroups... 

Small interference RNA siRNA-NCX1, siRNA-NCX1, siRNA-NCX3... 

For patients with leukemia, the transfer of siRNA-based strategies into clinical applicability will certainly be both frustrating and time-consuming and many hurdles still have to be overcome in order to realize the therapeutic potential of siRNAs. Efficient delivery of siRNA into the leukemic stem cell and their unknown influence of the patient s immune system are the most challenging issues that need to be addressed. 

In Huntington s disease the polyglutamine repeat expansion in exon 1 of HD leads to a toxic gain of the protein huntingtin (htt). Harper et al. could show that siRNA directed against mutant human htt reduced htt iriRNA and protein expression in cell culture and in HD... 

HSV2 (herpes simplex virus 2), which causes significant morbidity and is an important cofactor for the transmission of HIV infection was recently targeted in a mouse model by local application of siRNA mixed with lipids. The results suggested that siRNA could work as active components of microbicides to prevent viral infection or transmission [2]. 

Palliser D, Chowdhury D, Wang QY et al (2006) An siRNA-based microbicide protects mice from lethal herpes simplex vims 2 infection. Nature 439(7072) 89-94... 

Shen J, Samul R, Silva RL et al (2006) Suppression of ocular neovascularization with siRNA targeting VEGF receptor 1. Gene Ther 13 (3) 225-234... 

Small interfering RNAs (siRNA) are the mediators of gene-specific silencing by RNA interference. SiRNA stands for small interfering RNA duplexes. They are typically 21-23 bp in length. SiRNA were either chemically synthesised for experimental purposes or produced by Dicer-mediated cleavage of long double-stranded RNA. 

Kleimnan et al. 2008). In addition, synthetic siRNAs are also subject to degradation in vivo by nuclease activity. Besides side effects and instability, the efficient and specific delivery of the RNAi indncers to the target cell still requires optimization. Here we snmmarize the cnrrent statns of nncleic acid-based antiviral therapentics. The focns will be on antiviral strategies nsing antisense and RNAi technology. Additionally, antiviral ribozymes and aptamers will be discussed briefly, with a focus on recent studies. Gene therapy approaches and delivery systems are the subject of Chapter 11 of this book. 

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