Establishment and evaluation of methods for determinating cystic fibrosis transmembrane conductance regulator quantitatively / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To establish and evaluate a BA-ELISA method for the quantitative detection of cystic fibrosis transmembrane conductance regulator (CFTR) protein.</p><p><b>METHODS</b>We 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>The 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.</p>

Immunogenicity of recombinant human zona pellucida-3 peptides expressed in E. coli and efficacy of their antisera to inhibit in vitro human sperm-egg binding / 生理学报

The present study was aimed to analyze the immunogenicity of recombinant human zona pellucida-3 peptides (r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348)) expressed in E. coli through immunizing rabbits, and to evaluate the efficacy of their polyclonal antisera against r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348) to inhibit in vitro human sperm-egg binding respectively. Male New Zealand rabbits were immunized using r-huZP3a(22 approximately 176) or r-huZP3b(177 approximately 348) as antigen respectively, which was purified through an improved method of preparative gel polyacryulamide gel electrophoresis. The antibody response level of r-huZP3a(22 approximately 176) or r-huZP3b(177 approximately 348) immunogen in rabbits was determined by ELISA using mouse ZP3-5 (amino acid sequence(137 approximately 150) being completely conserved with huZP3(138 approximately 151) sequence) and specific huZP3-14 (amino acid sequence(327 approximately 340)) synthetic peptides as coating antigens respectively. The immunoreactivity and specificity of the anti-r-huZP3a(22 approximately 176) and anti-r-huZP3b(177 approximately 348) antisera with each r-huZP3 peptides, were tested by immunoblot and immunohistochemistry (using native huZP and human ovary section) respectively. A competitive hemizona assay (HZA) was used to evaluate the efficacy of the antisera against r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348) to inhibit in vitro human sperm-egg binding. Both r-huZP3 peptides were able to induce higher antibody titers in rabbits. Each antiserum could specifically recognize or bind to each target r-huZP3 peptide expressed in E. coli and native human ZP in vitro. The antisera also inhibited sperm-egg binding in the HZA. These results show that r-huZP3a(22 approximately 176) and r-huZP3b(177 approximately 348) are of strong immunogenicity. They can be used to develop a kit for detecting whether there are autoantibodies to zona pellucida in unexplained infertile women, and their antisera might be useful tools for determining minimal B-cell epitope sequences of several known huZP3 epitope peptides.

Expression and purification of three fusion proteins containing a single B-cell epitope (beta5, beta9 or beta8) of human chorionic gonadotropin beta subunit / 生物工程学报

The possibility of using a subunit or fragment of human chorionic gonadotropin (hCG) as an immunogen for birth control has been actively explored for many years. This protein homone is produced by the fertilized egg and is required for implantation of the blastocyst into the maternal uterus and the maitenance of pregnancy. In previous studies, several bio-synthesized hCG chimeric peptides (CP) that contain three linear B-cell epitopes (beta5, beta9 and beta8) of beta-hCG subunit together with various foreign 'promiscuous' T-cell epitopes were constructed and expressed as potential new hCG vaccine immunogens. In order to detect antibodies to each of the individual B-cell epitopes present in the animal antiserum raised against the hCG CPs, we decided to construct three recombinant proteins, each contains a single target B-cell epitope (betaE) of beta-hCG. Two sets of DNA fragments were chemically synthesized encoding the beta5, beta9 and beta8 epitopes (betaE) 45 approximately 52, 113 approximately 116 or 133 approximately 144 of beta-hCG subunit and were inserted into the downstream of streptavidin (Stv) gene in pTSA18 separately, with or without an extra TAA codon at the 3'-terminals of the genes. SDS-PAGE analysis revealed that only Stv-betaE (-beta5, -beta9 or -beta8) fusion genes set with the TAA codon can be expressed in E. coli BL21 (DE3) pLysS strain at high level after 1mM IPTG induction for 4 hours. Additionally, these fusion proteins can all be recognized by specific polyclonal antiserum (RS-4157) generated upon immunization with the loop peptide 38 approximately 57 of beta-hCG, monoclonal antibody (mAb) FB12 to beta9 epitope and mAb OT3A that specially recognizes reporter sequence 133 approximately 139 of beta8 epitope 137 approximately 144. Each of the proteins can be purified to 95% relative homogeneity using an improved method of preparative gel polyacrylamide gel electrophoresis. The yields were 5 mg per 1 L culture. The three target Stv-betaE fusion proteins will be useful in determining the immunogenicity of designed hCG CPs and hCG vaccines, including hCG DNA vaccines.