Beta Defensin-1 (DEFB1) displays potent microcidal properties, and also plays a part in other aspects of innate and adaptive immunity. DEFB1 genetic variations have been reported as contributing to hBD1 production impairment, leading to a greater susceptibility to be infected by oral pathogens, also leading to periodontitis. To counteract host immunity, cryptosporidium parvum has evolved multiple strategies to suppress host antimicrobial defense. One such strategy is to reduce the production of the antimicrobial peptide beta-defensin 1 (DEFB1) by host epithelial cells. Beta-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. It is reported that DEFb2 has been identified as an interactor of DEFb1, thus a binding ELISA assay was conducted to detect the interaction of recombinant human DEFb1 and recombinant human DEFb2. Briefly, DEFb2 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to DEFb1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-DEFb2 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 450/630nm immediately. The binding activity of DEFb1 and DEFb2 was shown in Figure 1. When recombinant human DEFb1 is lmmobilized at 2 ug/mL (100 uL/well), the concentration of rhDEFb2 that produces 50% optimal binding response is found to be approximately 0.11 ug/mL.