microRNAs and viral pathogenesis. (360G-Wellcome-088308_Z_09_Z)

miRNAs are small single-stranded RNA species of approximately 20-24 bases in length that regulate gene expression through post transcriptional mechanisms. We have used a biochemical approach to identify targets of miRNAs encoded by human cytomegalovirus (HCMV). This approach has already proven effective with the identification of multiple targets of one HCMV miRNA. These targets showed a striking over representation of genes involved in cell cycle control with predicted miRNA binding sites fo und almost exclusively within the 5 UTR. The assay will be used to screen all 11 HCMV miRNAs to gain valuable information on the function of viral miRNAs and miRNAs in general. The discovery of RNA interference has also proven to be a powerful tool for specific knock down of genes. However, toxic effects, bioavailability and cost have hampered in vivo use of small interfering RNAs. We have developed a system that allows highly effective, tissue specific, knock down of any viral gene using cel lular miRNA target sites. I will use this system to investigate the role of haematopoietic cells in CMV. This should also be a powerful approach for investigating a broad range of pathogenesis questions.