Polydeoxyadenylic-thymidylic acid (Poly(dA:dT)) sodium is a synthetic DNA polymer. Poly(dA:dT) sodium can be used to determine the activity of bound and free ribonucleic acid polymerase. Poly(dA:dT) sodiumis recognized by multiple PRRs (cytosolic DNA sensors (CDS), including cGAS, AIM2 , DAI, DDX41, IFI16, and LRRFIP1), and triggers the production of type I interferons. Poly(dA:dT) sodium can be used for the research of cancer and virus infection.