RIGI and viral infectious disease: To determine that RIG-I is the key nucleic acid sensor responsible for promoting A3A expression under the conditions of a viral infection, we monitored the levels of A3A mRNA following transfection of the RIG-I-specific agonist 3p-hpRNA, a 5′-triphosphate hairpin RNA structure residing in the influenza A (H1N1) virus genome37,40,42, in both MCF10A and BICR6 wild-type (WT) cells or multiple RIG-I-knockout (KO) clones.