CXCR5 and infection: In the LNs, early after infection, a significant transient increase of CXCR5+PD-1- is observed in all infected RMs peaking at day 14 (CXCR5+PD-1-, 45.28% ± 5.17%; p = 0.0011) compared to healthy RMs (CXCR5+PD-1-, 29.85% ± 2.26%) (Fig 3B, left upper panel).