CCL2 and infection: Expanding upon this, infection with Theiler’s murine encephalomyelitis virus (TMEV), which directly infects microglia, leads to the production of interferons, IL-1β, IL-6, interleukin-12 (IL-12), TNF, chemokine ligand 2 (CCL2), chemokine ligand 3 (CCL3), chemokine ligand 5 (CCL5), and inducible nitric oxide (iNOS).