30b and mir 30d show the opposite properties increased growth when over expressed and decreased growth when inhibited combining this work with expression analysis we demonstrate that mir 199a and mir 214 which derive from a common cluster are down regulated upon infection in both murine and human cytomegalovirus expression and network analysis suggests that mir 199a 3p regulates a range of genes involved in the immune response cellular movement and immune cell trafficking pooling experiments further demonstrate that mirnas which are clustered together mir 199a 5p mir 199a 3p and mir 214 can provide additive effects in inhibiting viral growth capacity host mirnas are a tune able and consequential feature of viral infection and provides the first evidence that these molecules hold broad anti viral potential against multiple viruses to define microrna hits the normalized fluorescent values obtained for the screens were plotted with a given virus as shown in fig4 the y axis represents values obtained in one screen median values based on n 3 and the x axis represents values obtained in another independent screen fig3 shows the 2 independent mcmv screens we excluded mimics that fell outside 2 st deviations dashed lines for the 2 screens as these are expected to be outliers we also excluded from this analysis mirnas that had toxicity or adhesion effects removed 26 of the total 301 unique mouse mirnas based on cell titre blue assay and visual inspection of wells we found a total of 21 mirnas that resulted in gt 1 5 u00d7 decrease on replication in two independent screens with all 3 viruses when transfected.