ITIH4 and infection: In particular, macrophage infiltration and satellite glial cell activation has been shown in rats exposed to gp120.70,71 Macrophage activation has also been shown in the DRG in SIV-infected macaques.9,37,39 The SIV models reporting macrophage activation are predominantly fast-progressing models, characterised by high viral loads, and therefore only inform about DRG pathogenesis at early stages of untreated infection.