title: Bicistronic expression plasmid encoding allergen and anti-IgE single chain variable fragment antibody as a novel DNA vaccine for allergy therapy and prevention.
abstract: Several approaches have been applied in order to alleviate the difficulties allergic patients are suffering from. Among them DNA vaccination and anti-IgE antibody have shown promising results. Herewith, a combination of both strategies is proposed to minimize IgE production while inducing high levels of blocking IgG and strong Th1 immune responses. A bicistronic expression plasmid including an internal ribosomal entry site (IRES) can express both, allergen and a single chain variable fragment (scFv) antibody against human IgE within antigen presenting cells (APCs) including B cells. Presentation of allergen derived peptides via MHC I and MHC II stimulates specific Th1 responses resulting in high levels of IFN-gamma and IgG. Anti-IgE scFv antibody binds to newly synthesized IgE molecules within B cell cytoplasm and also to free serum IgE, thereby inhibiting attachment of IgE to its receptors on basophils and mast cells. Also, IgE-anti-IgE complex functions as blocking antibody and neutralizes allergens entering the body. Additionally, anti-IgE scFv antibody binds to membrane bound IgE (mIgE) on B cells and interferes with IgE expression. Using assays, such as enzyme linked immunosorbent assay (ELISA), IgG and IgE production in response to this expression system can be evaluated. Also, rat basophil leukemia cell assay (using RBL-2H3 cells) can show the amount of functional IgE in sera as basophil mediator release is regarded as an indicator of the allergic hypersensitive reactions. The proposed approach may result in high levels of blocking IgG and low levels of IgE secretion from B cells. Additionally, it can inhibit activity of IgE in degranulation of basophils and mast cells.
authors.affiliation: Department of Biotechnology, Faculty of Science, University of Tehran, Enghelab Ave., P.O. Box 14155-6455, Tehran, Iran. aghaieba@khayam.ut.ac.ir
authors.forename: Nariman Aghaei
authors.initials: NA
authors.lastname: Bandbon Balenga
authors.forename: Josef
authors.initials: J
authors.lastname: Thalhamer
authors.forename: Richard
authors.initials: R
authors.lastname: Weiss
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005796:Genes; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology* / Q000517:prevention & control* / Q000628:therapy*; D006969:Hypersensitivity, Immediate / Q000517:prevention & control / Q000628:therapy; D007073:Immunoglobulin E / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D051381:Rats; D019444:Vaccines, DNA
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007135:Immunoglobulin Variable Region; D019444:Vaccines, DNA; C026408:anti-IgE antibodies; D007073:Immunoglobulin E