Polyomavirus T antigens! Nicholas Giacobbi et al. show, in their new Virology paper, that T antigen from SV40 and two human polyomaviruses, BKV and JCV, have the ability to induce an antiviral state in mouse embryonic fibroblasts. Additionally, they show that the antiviral state requires STAT1 expression. Chalk up another activity for the MAMU!