CCL5 and infection: Various secreted factors, such as the chemokine ligand CCL5, IFN, nitrous oxide, reactive nitrogen species and exosomes, play a role in restricting infection of astrocytes by several neurotropic viruses including herpes virus, human immunodeficiency virus and Junin virus (Gómez et al., 2003; Hu et al., 2012; Li et al., 2011).