The viral TLR3 agonist poly(I:C) stimulates phagocytosis and intracellular killing of Escherichia coli by microglial cells.

Stimulation of murine primary microglia with Toll-like receptor (TLR) agonists enhances their ability to phagocytose and kill bacteria. Here we show that the viral TLR3 agonist poly(I:C) stimulates the release of cyto-/chemokines and nitric oxide by microglia. Poly(I:C) increases microglial phagocytosis and intracellular killing of Escherichia coli K1, a pathogenic encapsulated bacterial strain, after 30 and 90 min of co-incubation. Stimulation with a viral epitope may strengthen the resistance of the brain to bacterial infections in vivo. Our data encourage animal experiments with poly(I:C) derivatives to assess whether this approach can increase the resistance of the CNS against bacterial infections.