OAS2 and viral infectious disease: Several ISGs were also found to be differentially regulated in the colonized animals including oas1g, oas1l, and oas2, casp4, ifit1, 2, and 3, gvin1, and ifi203. oas1g, oas1l, and oas2 belong to a family of pro-apoptotic, interferon-induced genes that are expressed in response to cell injury and viral infection.