ISG15 and tuberculosis: Unlike TB derived from term placenta, BAP-generated primitive TB of the early first trimester has diminished levels of 1) interferon-stimulated genes (ISG), such as ISG15, MX1, DDX58 (RIG-1), 2) interferon induced proteins with tetratricopeptide repeats (IFIT) family members, 3) and oligoadenylate synthase-like (OAS) family members, all of which augment the innate immune response to viral infection (44, 45).