Interleukin-29 (IL-29) is a member of the helical cytokine family and is a type III interferon. It is also known as IFNλ1 and is highly similar in amino acid sequence to the IL-28, the other type III interferon. IL-29 plays an important role in host defenses against microbes and its gene is highly upregulated in cells infected with viruses. Besides, ATPase, Ca Transporting, Plasma Membrane 2 (ATP2B2) has been identified as an interactor of IL29, thus a binding ELISA assay was conducted to detect the interaction of recombinant human IL29 and recombinant human ATP2B2. Briefly, IL29 were diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100μl were then transferred to ATP2B2-coated microtiter wells and incubated for 2h at 37 ℃. Wells were washed with PBST and incubated for 1h with anti-IL29 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 IL29 and ATP2B2 was shown in Figure 1, and this effect was in a dose dependent manner.