Use of integrase-minus lentiviral vector for transient expression

Lentivirus-derived vectors are among the most promising viral vectors for gene therapy which is currently available, but their use in clinical practice is limited due to associated risk of insertional mutagenesis. Gene targeting is an ideal method for gene therapy, but it has low efficiency in comparison to viral vector methods. In this study, we are going to design and construct an integrase-minus lentiviral vector. This vector is suitable for transient expression of gene and gene targeting with viral vector. In this experimental study, three missense mutations were induced in the catalytic domain of Integrase gene in the pLP1 plasmid and resulted D64V, D116A and E152G changes in the amino acid sequence through site directed mutagenesis. The pLenti6.2-GW/EmGFP transfer vector, associated with native and mutated packaging mix, was transfected into 293T cell line. In order to titer the lentivirus stock, the viruses were harvested. Finally, the viruses transduced into COS-7 cell line to assess green fluorescent protein [GFP] gene expression by a fluorescence microscopy. Recombinant and wild lentiviruses titer was about 58×10[6] transducing units/ml in COS-7 cell line. The number of GFP-positive cells transduced with native viruses was decreased slightly during two weeks after viral transduction. In contrast, in the case of integrase-minus viruses, a dramatic decrease in the number of GFP positive cells was observed. This study was conducted to overcome the integration of lentiviral genome into a host genome. Nonintegrating lentiviral vectors can be used for transient gene expression and gene targeting if a Target gene cassette is placed in the lentivirus gene structure. This combination method decreases disadvantages of both processes, such as random integration of lentiviruses and low efficiency of gene targeting

Design and construction of two yeast shuttle vectors containing human procollagen genes expression cassette for expression in yeast

Collagens are the most abundant proteins in the human body. Their main function is to provide structural and mechanical support for the tissues, but they are also involved in a number of other biological functions including cell attachment, migration and differentiation. Collagens and gelatins are widely used in pharmaceutical and medical applications. Every year, more than 50,000 tons of collagen and gelatin are used in medical applications. These materials may have some viral and prion impurity and/or stimulate allergic responses in human body. Therefore, scientists have produced human collagen in recombinant systems. In this study we have constructed two yeast shuttle vectors containing human procollagen genes expression cassette for expression in yeast. Total RNA was extracted from human skin fibroblast cell line, and cDNA synthesis was done by oligo dt. Then gene fragments were amplified from the cDNA with the necessary changes by Polymerase Chain Reaction [PCR]. Finally they were cloned in yeast vector pPICZ alpha A containing regulatory sequences for expressing and secreting the polypeptide product. Two yeast shuttle vectors containing human COL1A1 and COL1A2 expression cassettes were created. Final constructs were confirmed by enzymatic digestion, PCR of desired fragment and sequencing. The yeast shuttle vectors containing human COL1A1 and COL1A2 can be transferred into the yeast in the later stages to determine the scale of expression

[Production of camel polyclonal antibody against vascular endothelial growth factor receptor-2 and performance evaluation in ELISA test]

In molecular approach, serum of camel contains a unique type of antibodies devoid of light chains since the light chain is missing, the heavy-chain antibodies should bind their antigen by one single domain, the variable domain of the heavy immunoglobulin chain. Vascular endothelial growth factor receptor-2 [VEGFR-2] is one of the important proteins in angiogenesis which over-expressed in many types of tumors. Two male dromedaries [Camelus dromedarius] were immunized against VEGFR-2. ELISA was used to evaluate the immunization process. Camel immune sera were fractionated with protein A and G affinity chromatography. Heavy chain antibodies tested for its specific reactivity in cell-based ELISA in recognition of VEGFR-2 on the cell surface of three cell lines; 293/KDR, HUVECs and A431. In ELISA test, the camel sera in 1/12800 dilution had the acceptable results. Furthermore, cell-based ELISA demonstrated that the polyclonal heavy chain antibodies bind to VEGFR-2 in 293/KDR and HUVECs cell lines. Single chain polyclonal antibodies against VEGFR-2 can be used for detection of soluble form of this protein by ELISA, and also flowcytometry, western blotting and immunohistochemistry