ISG15 and infection: Among the proteins with the largest increase in infected cells at 3 and 7 days after infection were several proteins involved in IFN-α and IFN-γ responses, such as the IFN-induced proteins IFIT1, IFIT2, IFIT3, and IFIT5, the IFN-stimulated proteins ISG15 and ISG20, the viral RNases OAS1 and OAS2, and the antigen-presenting molecules class I – β-2 microglobulin (B2M) and HLA-A/-B/-E.