BTLA and infection: WT mice were treated with the 6A6 antibody one day prior to LM-OVA infection and again at day 2 p.i. Blockade of the HVEM-BTLA interaction with the anti-BTLA mAb led to a significant reduction in the percentages and absolute numbers of antigen-specific CD8+ T cells in the spleen of infected mice at day 7 (Figure 7A).