Hierarchical cluster of differentially expressed genes across time points. This is a graphical representation of the ratio between animals inoculated and non-inoculated for those 87 genes differentially expressed with a fold-change higher than 1.7 or lower than 0.6 in at least one time point. Among the methods tested, we selected the "Manhattan" method to measure the distance between genes and the "Ward" algorithm to cluster genes. Rows are genes and columns time points. At the top, the color log2 scale indicates the expression level of treated animals compared with the control ones. Genes colored in red are more expressed in BSE inoculated animals than in control ones, whereas genes colored in green are more expressed in control animals. Genes that are more up regulated are highlighted in the figure.