IFN-g is a dimerized soluble cytokine that is the only member of the type II class of interferons. The importance of IFNg in the immune system stems in part from its ability to inhibit viral replication directly and most importantly from its immunostimulatory and immunomodulatory effects. IFN-gamma dimers bind to IFN-gamma RI ( alpha subunits) which then interact with IFN-gamma RII ( beta  subunits) to form the functional receptor complex of two alpha and two beta  subunits. Inclusion of IFN-gamma RII increases the binding affinity for ligand and the efficiency of signal transduction. A functional binding ELISA assay was conducted to detect the interaction of recombinant pig IFN-g and recombinant human IFNgR1. Briefly, IFN-g was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to IFNgR1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-IFN-g pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630 nm immediately. The binding activity of recombinant pig IFN-g and recombinant human IFNgR1 was shown in Figure 1, the EC50 for this effect is 0.38 ug/mL.