Specificity of COX1 and COX2 antibodies in simian immunodeficiency virus (SIV)-induced encephalitis. (A–D) As shown in images of serial sections with immunohistochemistry (IHC) against COX1 (A, B) and COX2 (C, D), stainings are not preabsorbed with excess heterologous peptides (A, C) but with their cognate homologous peptides (B, D), respectively, confirming that the antibodies specifically detect the partially overlapped expression of COX1 and COX2 in macrophages (arrows) and multinucleated giant cells (double arrow heads) in SIV-induced encephalitis as demonstrated on adjacent sections (A, C). Scale bars = (A–D) 50 µm.