IL-1β^XAT A/a and B/b mice and WT controls were injected unilaterally in the dentate gyrus with approximately 1.5 × 10⁴ infectious units of FIV-Cre. Inflammatory indices were assayed 2 weeks later. (A) Microglial activation was demonstrated by increased staining intensity of Iba-1 (green) and MHC class II (red) in B/b and A/a relative to WT mice, with colocalization appearing yellow. Insets show higher-magnification morphologic changes among Iba-1–positive cells residing in the dentate gyrus. (B) Astrocyte activation, as evidenced by increased GFAP expression, was demonstrated in the dentate gyrus of B/b animals only. Scale bars: 50 μm (A and B); 10 μm (insets in A). (C and D) qRT-PCR analysis compared relative abundance of gene transcripts in ipsilateral (I) and contralateral (C) hippocampi. Analysis revealed significant upregulation of MHC class II in A/a and B/b mice (C), but significant upregulation of GFAP in B/b mice only (D), compared with WT controls. n = 3–4 per group. Data are mean ± SEM. *P < 0.05 versus respective WT.