An increase in the number of CCR5+ cells in the brain of SIV‐infected animals with encephalitis was accounted for by increased CD3+CD8+ cells expressing CCR5, but not by increased CCR5+ microglia or perivascular macrophages (PVMs), and a concurrent decrease in the percentage of CCR5+ PVMs was observed. The gene discussed is CCR5; the disease is encephalitis.