OBJECTIVETo establish and evaluate a BA-ELISA method for the quantitative detection of cystic fibrosis transmembrane conductance regulator (CFTR) protein.

METHODSWe deliberately selected three tables of CFTR and made the synthetic peptide be expressed in E. coli, then used the antigen to immunize rabbits to obtain the anti-CFTR polyclonal serum. After that, 96 well plates were coated with the purified antibody against CFTR. The antigen CFTR which was extracted from human sperm was detected by anti-CFTR antibody labeled with biotin, horseradish peroxidase conjugated avidin, and the substrate. The concentrations of two kinds of antibodies and the experiment parameters were optimized. Thereby, the double antibody sandwich BA-ELISA method for the quantitative detection of CFTR protein was established. Furthermore, the reproducibility, specificity and so on were evaluated by clinical specimens of sperm.

RESULTSThe optimal concentration of coated anti-CFTR IgG was 4 µg/ml, while the biotin labeled anti-CFTR IgG was 10 µg/ml; the optimal blocking buffer was 1% BSA-PBST, the optimal time of the reaction between antigen and antibody was 60 min, the optimal chromogenic time was 15 min, the intra-assay and inter-assay coefficient were 2.16%-9.23% and 2.29%-11.71% respectively; The lowest detectable limit was 0.15 ng/ml; the standard curve had a good linear correlation of R2 = 0.962.

CONCLUSIONThe BA-ELISA method for the quantitative detection of CTFR protein is successfully established, and it is demonstrated that the method has strong specificity, high sensitivity and good reproducibility. It provides the basis and evidence of the further application of the method.