Cloning and Expression of Nano Body Gene against Enterotoxin B of Staphylococcus Aureus

Background & Objectives: Staphylococcus aureus bacteria causes many different diseases by secretion of various enterotoxins. Therefore, it is necessary to develop ways that facilitate the detection of enterotoxins. Nowadays, immunochemical methods which are based on monoclonal antibody technology are used. The heavy chain antibodies that are called VHH or Nano body were found in blood serum of the Camelidae family. The unique properties of this antibody such as their binding to small molecules like toxins make them attractive candidates for the development of immunodiagnostic tests. The present study was done to achieve a VHH molecules against Staphylococcus enterotoxin B. Materials & Methods: Freighting phage library for isolate private Nano bodies against enterotoxin B was done in previous works. Next, pCANTAB 5E vector that consists VHH, extracted from E.coli bacteria strain xl1blue, and after doing PCR process with relative primers, sub cloning in pET21a(+) as an expression vector with cut sites NdeI and XhoI was done. Transformation in E.coli bacteria strain BL21(DE3) was done. Then, the cells effected with IPTG and producing time, and other terms were optimized. Finally, the expression of the protein with SDS-PAGE and western blot techniques was evaluated. Result: For proving cloning of nano body gene in pET21a (+) vector, nucleotide sequence of gene was analyzed, and transforming to E.coli bacteria strain BL21(DE3) was successful. After inspiration, active protein in cell was seen by SDS-PAGE technique and proved by western blot. Conclusion: cloning, sub cloning, and nonabody expression were surveyed in this research. Production of this protein can help to develop new therapeutic methods and produce vaccine against enterotoxin B of Staphylococcus aureu

Design of Chlamydia Trachomatis Diagnostic Kit in Symptomatic Women Using Real Time PCR

Background & Objective: Chlamydia trachomatis is one of the most common sexually transmitted diseases worldwide. Screening women for Chlamydia trachomatis in developing countries is highly desirable due to the ineffectiveness of the available diagnostic methods. The aim of this study is to design a detection kit for Chlamydia trachomatis in symptomatic women. Materials & Methods: A total of 50 clinical specimens of symptomatic women were collected. The OMP1 gene sequence was extracted from the gene bank and the primer and probe were designed appropriately by Mega6 software. The extracted DNA was amplified by PCR. In order to provide positive control, PCR product was cloned into Pjet1.2 vector. To determine the sensitivity, DNA dilution was performed. To determine the specificity, DNA of vaginal bacteria was extracted and Real Time PCR was done. Results: In this study, we designed a kits with 100% specificity and 10pg/ϥl sensitivity in detecting chlamydial infection in symptomatic women. Conclusion: With the use of designed primers and real time, we can detect 100% of chlamydia infections

Expression and Purification of Soluble form of Human Parathyroid Hormone (rhPTH1-34) by Trx Tag in E. coli

Background: Parathyroid Hormone (PTH) is secreted by parathyroid glands and controls the level of calcium in bones and kidney. PTH is a small polypeptide with 84 amino acids, but the first 34 amino acids of which are enough for hormone biological activity and can be used in the treatment of Osteoporosis. The expression efficiency of recombinant human parathyroid hormone rhPTH (1-34) or Teriparatide using a cleavable fusion protein strategy was compared in two strains of E. coli. Materials and Methods: A cassette was designed and fully synthesized for prokaryotic expression of rhPTH using pET system. From 5’ to 3’, the cassette consisted of: Trx tag to increase the solubility of protein, His tag for purification and detection of protein, enterokinase site to cleave all fusion moieties, and an optimized gene code for Teriparatide corresponding to the amino acid sequence of hPTH. This cassette was cloned into pET32a vector. The vector was simultaneously transformed and expressed in two different E. coli strains. The ability of strains for expression of this recombinant pharmaceutical was compared. Early expression was confirmed by SDS-PAGE and Western Blotting. The soluble fusion protein was harvested and purified by immobilized affinity chromatography. Then the fusion moiety was released from Teriparatide by enterokinase digestion. Results: The fusion form of rhPTH was efficiently expressed in both E. coli strains. However, the percentage of the target protein to the total protein content in Rosetta-gami was more than its amount in BL21 (­60 % vs 25%).The fusion protein was highly purified with Ni-NTA column. Up to 18.5 mg/ml of pure fusion protein has been obtained from 1-liter Rosetta-gami strain of E. coli. The pure Teriparatide was released by enterokinase digestion. Conclusion: The pure rhPTH (1-34) produced here, could be the subject for biological activity and quality control assessments, and following formulation processing, it could be applied as a peptide drug in the treatment of Osteoporosis. &nbsp