Cell signaling through the PD-1 receptor upon binding the PD-L1 ligａnd attenuates immune responses and this pathway is exploited by both tumors and viruses. The Monkey PD-1[Biotinylated]:PD-L1 Inhibitor Screening Assay Kit is designed for screening and profiling inhibitors of this signaling pathway in the animal model cynomolgus monkey (Macaca fascicularis). The key to this kit is the high sensitivity of detection of biotin-labeled PD-1 by streptavidin-HRP. Only a few simple steps on a microtiter plate are required for the assay. First, PD-L1 is coated on a 96-well plate. Next, PD-1 is incubated with PD-L1 on the plate. Finally, the plate is treated with streptavidin-HRP followed by addition of an HRP substrate to produce chemiluminescence, which can then be measured using a chemiluminescence reader.