The main role of factor VII (FVII) is to initiate the process of coagulation in conjunction with tissue factor (TF). Tissue factor is found on the outside of blood vessels-normally not exposed to the bloodstream. Upon vessel injury, tissue factor is exposed to the blood and circulating FVII. Once bound to TF, FVII is activated to FVIIa by different proteases, among which are thrombin (factor IIa), factor Xa, IXa, XIIa, and the FVIIa-TF complex itself. Tissue Factor (TF) has been identified as an interactor of FVII, thus a binding ELISA assay was conducted to detect the interaction of recombinant rat FVII and recombinant rat TF. Briefly, FVII were diluted serially in PBS, with 0.01%BSA (pH 7.4). Duplicate samples of 100uL were then transferred to TF-coated microtiter wells and incubated for 2h at 37℃. Wells were washed with PBST and incubated for 1h with anti-FVII pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50μL stop solution to the wells and read at 450nm immediately. The binding activity of of FVII and TF was shown in Figure 1, and this effect was in a dose dependent manner.