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Citrus tristeza virus (CTV) is among the most destructive pathogens of citrus and causes substantial economic losses in citrus-growing industry worldwide. Considering recent distribution of this pathogen and its capability of transmission by existing aphid vectors in Iran, detection of this virus is enforceable for controlling the damage caused by this pathogen in Iran, as one of the major citrus producing countries. Toward this aim, developing a reliable and sensitive detection method such as enzyme- linked immunosorbant assay (ELISA) would be the first step to detect CTV in large scale screenings of field samples. As the serological method requires great amounts of specific antibody, the consequent preparation of a large scale antigen source for immunization process is necessary. In this study the coat protein gene of CTV (CP25) was amplified by polymerase chain reaction from a cloned CP25 gene in pTZ57R/T and subcloned in pET26b expression vector and named pET-CP25. Two Escherichia coli strains of BL21 and Rosetta Gami (DE3) were transformed by pET-CP25. Expression of recombinant protein was induced by IPTG. The authenticity of recombinant protein was confirmed by western immunoblot analysis using a polyclonal antiserum against CTV particles. The results indicated that CTV coat protein gene was expressed in E.coli. This recombinant protein could be used as a source of antigen for immunization process.

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Serological methods are commonly used methods for detection of viruses. Preparation of pure viral antigens is a crucial step in production of antibodies required for serological studies. In this research the gene encoding coat protein of a Beet western yellows virus (BWYV) isolate from Iran was amplified by PCR and was ligated into a bacterial expression vector (pET26b) to obtain pET-BWYV-CP clone. Escherichia coli BL21 was transformed with pET-BWYV-CP and expression of the recombinant coat protein was induced by IPTG. The expressed recombinant coat proteins were purified and used as an antigen for rabbit immunization. The antiserum was able to detect recombinant coat protein in total protein extracts of induced E. coli BL21 cells in western blot analysis.  

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Cucumber mosaic virus (CMV) is one of widely-spread viruses of plants with the broadest host range encompassing over 1200 species. One major limiting factor for detection of the virus is unavailability of the virus-specific antibodies especially in developing countries. Recombinant DNA technology facilitates antibody preparation without requiring special equipment. In this study, coat protein (CP) gene cDNA of CMV was subcloned from pTZ57CMVCP into pET21a expression vector and transformed into Escherichia coli strain Rosetta. Expression of CMV CP was examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and its identity was confirmed by western blotting, dot blot immunobinding assay (DIBA) and enzyme- linked immunosorbent assay (ELISA) using anti- CMV antibody. The expressed protein was purified using T7•Tag affinity purification kit and used as antigen for raising polyclonal antibodies in two mice. The purified anti-CMV CP IgG and the conjugated IgG performed favourably in terms of specificity and sensitivity to detect both expressed CP (antigen) and CMV isolates in infected cucurbit plants using plate trapped antigen (PTA)- ELISA, double-antibody sandwich (DAS)-ELISA and western blotting. The prepared antibodies can be applied in serological and sero-molecular tests in studies on the virus and in screening of plants for the infection. This is the first report of preparation of antibodies against CP of an indigenous isolate of CMV.

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Introduction: Amyloid beta (Aβ) is the major constituent of harmful plaques in the Alzheimer’s patients. Thus, study of Aβ and understanding its related molecular and cellular mechanisms is essential for diagnosis and therapeutic interventions. This study introduces a rapid, simple, and cost-effective technique for production and purification of this peptide, utilizing the expression of Aβ gene within bacterial system.
Materials and methods: Aβ gene was synthesized and transferred into the expression vector pET26b. After induction by Lactose and  24 hours of incubation for Aβ expression the cell sediment was analyzed for presence of recombinant peptide using SDS-PAGE and Western blot.  Then the purification of recombinant peptide was carried using nickel chloride affinity chromatography. Characterization of purified Aβ was performed by evaluating cell cytotoxicity in 25 µM and 50 µM concentrations using MTT assay on Alzheimer cell line model SH-SY5Y.
Results: Colony PCR and sequencing results showed the correct insertion of Aβ coding fragment into the expression vector. Presence of bands with the expected size in the results of SDS PAGE and western blot had confirmed successful expression of his-tagged recombinant peptide. MTT assay results showed the purified peptide has respectively 30 and 50% cytotoxicity for 25 µM and 50 µM concentrations.
Discussion: Production of amyloid beta peptide in bacterial hosts seems to be favorable. Obtaining Aβ peptide in soluble phase is an important advantage of this study. Hence according to toxicity of the purified peptide, it can be utilized for cell line treatments and further researches on Alzheimer disease.