title: Identification and immunogenic potential of B cell epitopes of outer membrane protein OmpF of Aeromonas hydrophila in translational fusion with a carrier protein.
abstract: Aeromonas hydrophila, a ubiquitous and virulent bacterial pathogen, affects a variety of fishes, including Labeo rohita. Existing treatment strategies comprise antibiotic therapies and attenuated bacterial strain-based vaccines. No functional subunit vaccine has been available until now. Given their key role in determining pathogenicity, outer membrane proteins have been successfully explored as potential vaccine candidates. We have devised a direct strategy for eliminating non-specific responses by selectively aiming the immune response against specific immunodominant epitopes of the outer membrane protein F (OmpF) of A. hydrophila (AhOmpF). Five putative epitopes of AhOmpF predicted in silico were genetically conjugated with heat labile enterotoxin chain B of E. coli (LTB). Recombinant fusion proteins expressed in E. coli were purified from solubilized inclusion bodies and refolded. The fusion protein retained GM1 ganglioside receptor binding activity of LTB, indicating proper folding. Four of the five fusion proteins were found to be highly immunogenic. Of the four proteins, antisera against the fusion protein (anti-rEpiF1) harboring 66-80 amino acid residues of the OmpF gave maximum cross-reactivity with the targeted rOmpF in enzyme-linked immunosorbent assay (ELISA) and was able to recognize both fusion partners-rOmpF and rLTB-in Western blot. Antibody isotyping of the antisera and cytokine array analysis of the culture supernatants of splenocytes from sensitized mice manifested a mixed Th1/Th2 immune response with a bias toward Th2. Anti-rEpiF1 antibodies were able to bind to the cell membrane of live A. hydrophila cells and agglutinate them. Our results thus suggest that the OmpF epitope (66-80) in fusion with a carrier protein is a promising vaccine candidate against A. hydrophila.
authors: Gene Regulation Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
authors: Mahima
authors: M
authors: Sharma
authors: Aparna
authors: A
authors: Dixit
mesh_terms: D016980:Aeromonas hydrophila / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004768:Enterotoxins / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D018985:Epitopes, B-Lymphocyte / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018272:Porins / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D002352:Carrier Proteins; D004768:Enterotoxins; D018985:Epitopes, B-Lymphocyte; D029968:Escherichia coli Proteins; C109237:OmpF protein; D018272:Porins; D011993:Recombinant Fusion Proteins; C027538:heat-labile enterotoxin, E coli