Infiltrated macrophages were found in the dorsal root ganglia (DRG) of AIDS patients with a history of HIV-SN.10 Simian immunodeficiency virus (SIV) only infects macrophages, not neurones, in the primate DRG, mirroring the process observed in humans10, 11 and contradicting the theory of direct gp120 neurotoxicity. The gene discussed is ITIH4; the disease is AIDS.