In silico experiment with an-antigen-toll like receptor-5 agonist fusion construct for immunogenic application to Helicobacter pylori.

BACKGROUNDS: Helicobacter pylori colonize the gastric mucosa of half of the world's population. Although it is classified as a definitive type I carcinogen by World Health Organization, there is no effective vaccine against this bacterium. H. pylori evade the host immune response by avoiding toll-like detection, such as detection via toll-like receptor-5 (TLR-5). Thus, a chimeric construct consisting of selected epitopes from virulence factors that is incorporated into a TLR-5 ligand (Pseudomonas flagellin) could result in more potent innate and adaptive immune responses. MATERIALS AND METHODS: Based on the histocompatibility antigens of BALB/c mice, in silico techniques were used to select several fragments from H. pylori virulence factors with a high density of B- and T-cell epitopes. RESULTS: These segments consist of cytotoxin-associated geneA (residue 162-283), neutrophil activating protein (residue 30-135) and outer inflammatory protein A (residue 155-268). The secondary and tertiary structure of the chimeric constructs and other bioinformatics analyses such as stability, solubility, and antigenicity were performed. The chimeric construct containing antigenic segments of H. pylori proteins was fused with the D3 domain of Pseudomonas flagellin. This recombinant chimeric gene was optimized for expression in Escherichia coli. The in silico results showed that the conserved C- and N-terminal domains of flagellin and the antigenicity of selected fragments were retained. DISCUSSION: In silico analysis showed that Pseudomonas flagellin is a suitable platform for incorporation of an antigenic construct from H. pylori. This strategy may be an effective tool for the control of H. pylori and other persistent infections.

Development of quantitative competitive PCR for determination of copy number and expression level of the synthetic glyphosate oxidoreductase gene in transgenic canola plants

Background: For successful in vitro plant regeneration, plant cell lines with multiple transgene integration and low transgene expression levels need to be ruled out. Although real-time polymerase chain reaction (RT-PCR) is a rapid way to accomplish this, it is also expensive and typically limits the size of the target sequence. Quantitative competitive PCR (QC-PCR) is proven to be a safe and accurate method for determination of both copy number and quantification of transcript levels of synthetic transgenes in transformed plants. Results: The glyphosate oxidoreductase genewas chemically synthesized and used to transform Brassica napus L. via Agrobactrium-mediated transformation. A construct containing the mutated form of a synthetic glyphosate oxidoreductase (gox) gene (internal standard) was prepared. Gene copy number was estimated in nine independent transgenic lines using QC-PCR as well as the standard method of Southern blot analysis. By quantitative RT-PCR, transcript levels were also determined in these lines. High (> 3), medium to high (2.2-3), medium to low (1-2.2), and low (< 1) levels of transcript were detected. Conclusions: No direct relationship was found between copy number and transgene expression levels. QC-PCR method could be implemented to screen putative transgenic plants and quickly select single T-DNA inserts. QC-PCR methods and the prepared competitor construct may be useful for future quantification of commercial transgenic food and feed.