The impacts of a fliD mutation on the biofilm formation of Helicobacter pylori

Objective To investigate the impact of the fliD gene on the biofilm formation of Helicobacter pylori (H. pylori). Methods H. pylori fliD mutant was constructed using inverse PCR mutagenesis. The mobility of the bacteria and its adhesion ability to human epithelial cells were assessed using a motility assay and a fluorescein isothiocyanate staining adhesion assay, respectively. The formation of biofilm was evaluated using a pellicle assay and a crystal violet staining assay. The cyto-architecture of the biofilm was documented with scanning electron microscopy. Results It was found that there was no significant difference in the levels of bacterial adhesion and the biofilm formation between the wild-type ATCC 43504 and the fliD mutant. Apart from a poor motility, the fliD mutant had a slightly delayed formation of its biofilm and an incomplete cyto-architecture of its biofilm. The bacterial cells residing in the biofilm of the fliD mutant showed a loose accumulation with less apparent cross-linking fibrils. Most of the mutant cells had truncated flagella. Conclusions This study provides the preliminary evidences that fliD potentially regulates biofilm formation and is required for the motility of H. pylori. Further studies need to be performed in order to develop fliD as a novel target for vaccine or antimicrobial agent in future.

Specific B-cell Epitope of Per a 1: A Major Allergen of American Cockroach (Periplaneta americana) and Anatomical Localization

PURPOSE: Cockroach (CR) is a common source of indoor allergens, and Per a 1 is a major American CR (Periplaneta americana) allergen; however, several attributes of this protein remain unknown. This study identifies a novel specific B cell epitope and anatomical locations of Per a 1.0105. METHODS: Recombinant Per a 1.0105 (rPer a 1.0105) was used as BALB/c mouse immunogen for the production of monoclonal antibodies (MAb). The MAb specific B cell epitope was identified by determining phage mimotopic peptides and pair-wise alignment of the peptides with the rPer a 1.0105 amino acid sequence. Locations of the Per a 1.0105 in P. americana were investigated by immunohistochemical staining. RESULTS: The rPer a 1.0105 (~13 kDa) had 100%, 98% and > or =90% identity to Per a 1.0105, Per a 1.0101, and Cr-PII, respectively. The B-cell epitope of the Per a 1.0105 specific-MAb was located at residues99 QDLLLQLRDKGV110 contained in all 5 Per a 1.01 isoforms and Per a 1.02. The epitope was analogous to the Bla g 1.02 epitope; however, this B-cell epitope was not an IgE inducer. Per a 1.0105 was found in the midgut and intestinal content of American CR but not in the other organs. The amount of the Per a 1 was ~544 degrees Cg per gram of feces. CONCLUSIONS: The novel Per a 1 B-cell epitope described in this study is a useful target for allergen quantification in samples; however, the specific MAb can be used as an allergen detection reagent. The MAb based-affinity resin can be made for allergen purification, and the so-purified protein can serve as a standard and diagnostic allergen as well as a therapeutic vaccine component. The finding that the Per a 1 is contained in the midgut and feces is useful to increase yield and purity when preparing this allergen.

Specific B-cell Epitope of Per a 1: A Major Allergen of American Cockroach (Periplaneta americana) and Anatomical Localization

PURPOSE: Cockroach (CR) is a common source of indoor allergens, and Per a 1 is a major American CR (Periplaneta americana) allergen; however, several attributes of this protein remain unknown. This study identifies a novel specific B cell epitope and anatomical locations of Per a 1.0105. METHODS: Recombinant Per a 1.0105 (rPer a 1.0105) was used as BALB/c mouse immunogen for the production of monoclonal antibodies (MAb). The MAb specific B cell epitope was identified by determining phage mimotopic peptides and pair-wise alignment of the peptides with the rPer a 1.0105 amino acid sequence. Locations of the Per a 1.0105 in P. americana were investigated by immunohistochemical staining. RESULTS: The rPer a 1.0105 (~13 kDa) had 100%, 98% and > or =90% identity to Per a 1.0105, Per a 1.0101, and Cr-PII, respectively. The B-cell epitope of the Per a 1.0105 specific-MAb was located at residues99 QDLLLQLRDKGV110 contained in all 5 Per a 1.01 isoforms and Per a 1.02. The epitope was analogous to the Bla g 1.02 epitope; however, this B-cell epitope was not an IgE inducer. Per a 1.0105 was found in the midgut and intestinal content of American CR but not in the other organs. The amount of the Per a 1 was ~544 degrees Cg per gram of feces. CONCLUSIONS: The novel Per a 1 B-cell epitope described in this study is a useful target for allergen quantification in samples; however, the specific MAb can be used as an allergen detection reagent. The MAb based-affinity resin can be made for allergen purification, and the so-purified protein can serve as a standard and diagnostic allergen as well as a therapeutic vaccine component. The finding that the Per a 1 is contained in the midgut and feces is useful to increase yield and purity when preparing this allergen.