Follicular SIV-specific CD8 T cells were largely excluded from germinal centers (GC) during early SIV infection.

(A) Representative images demonstrate the distribution of SIV-specific CD8 T cells within B cell follicles during early SIV infection. Sections were stained with Mamu-A1*001/Gag CM9 tetramers to label SIV-specific CD8 T cells (red, and indicted with arrows in the image on the right which shows tetramer staining alone), IgM antibodies (blue) to define follicles (F), and Ki67 antibodies (green) to label GC. Confocal images were collected with a 20X objective and each scale bar indicates 100 μm. (B) Frequencies of follicular tetramer+ SIV-specific CD8 T cells in GCs were 56% (95% CI: 30%, 73%) lower than those in non-GC follicular area (p = 0.005).