poly(I:C)

Polyinosinic:polycytidylic acid (usually abbreviated poly I:C) is an immunostimulant. It is used in the form of its sodium salt to simulate viral infections.
Poly I:C is known to interact with toll-like receptor 3 (TLR3), which is expressed in the membrane of B-cells, macrophages and dendritic cells. Poly I:C is structurally similar to double-stranded RNA, which is present in some viruses and is a "natural" stimulant of TLR3. Thus, Poly I:C can be considered a synthetic analog of double-stranded RNA and is a common tool for scientific research on the immune system.