TLR3 and viral infectious disease: In a prototypical MIA regimen13, pregnant dams are treated on embryonic day 12.5 (E12.5) with polyinosinic:polycytidylic acid (Poly I:C)—a toll-like receptor-3 (TLR3) agonist that simulates an innate response to viral infection—which exposes offspring to immune challenge in utero.