Twenty five of the 5,757 DE genes were common to all pathogen challenges (Table 3) and function in clusters of secreted and extracellular proteins such as the ubiquitin-like modifier ISG15, which is induced by IFN-α/β and plays an essential role in innate immunity against viral and bacterial infections [50], Tf which is important to cell proliferation through the supply of iron for DNA synthesis [51], MMP9 which is an important protease that is involved in the breakdown of the extracellular matrix and leukocyte recruitment [52] and CXCL9 which is involved in T cell trafficking [53]. Here, ISG15 is linked to bacterial infectious disease.