Fundamental properties of the mammalian innate immune system revealed by multispecies comparison of type I interferon responses
(A) A heatmap displaying the results of a similarity search–based screen of 111 mammalian genomes for sequences disclosing homology to mammalian core ISGs. Each column represents a distinct mammalian species, while each row represents a coremamm ISG. Numbers on the left of each row identify each ISG as listed in S3 Table. Column numbers refer to species (S4 Table). Colours are proportional to the number of matches found in each genome, normalised by the median hit count for that gene across the Mammalia. Because the method is based upon sequence-similarity screening, high count levels for a particular gene do not necessarily reflect gene expansion. Note that the grey boxes indicate that no matches were identified, either due to a bona fide deletion or as a result of relatively poor quality of the genomes. Note that only 79 coremamm ISGs are included in the analysis. Some of the coremamm ISGs were excluded from this analysis because of their high levels of similarity between each other posing a risk for spurious results. (B) A cartoon of syntenic loci showing the absence of IFIT3 and pseudogenisation of IFIT2 in cetaceans. ISGs, interferon-stimulated genes.