title: Immunization with Hypoallergens of shrimp allergen tropomyosin inhibits shrimp tropomyosin specific IgE reactivity.
abstract: Designer proteins deprived of its IgE-binding reactivity are being sought as a regimen for allergen-specific immunotherapy. Although shrimp tropomyosin (Met e 1) has long been identified as the major shellfish allergen, no immunotherapy is currently available. In this study, we aim at identifying the Met e 1 IgE epitopes for construction of hypoallergens and to determine the IgE inhibitory capacity of the hypoallergens. IgE-binding epitopes were defined by three online computational models, ELISA and dot-blot using sera from shrimp allergy patients. Based on the epitope data, two hypoallergenic derivatives were constructed by site-directed mutagenesis (MEM49) and epitope deletion (MED171). Nine regions on Met e 1 were defined as the major IgE-binding epitopes. Both hypoallergens MEM49 and MED171 showed marked reduction in their in vitro reactivity towards IgE from shrimp allergy patients and Met e 1-sensitized mice, as well as considerable decrease in induction of mast cell degranulation as demonstrated in passive cutaneous anaphylaxis assay. Both hypoallergens were able to induce Met e 1-recognizing IgG antibodies in mice, specifically IgG2a antibodies, that strongly inhibited IgE from shrimp allergy subjects and Met e 1-sensitized mice from binding to Met e 1. These results indicate that the two designer hypoallergenic molecules MEM49 and MED171 exhibit desirable preclinical characteristics, including marked reduction in IgE reactivity and allergenicity, as well as ability to induce blocking IgG antibodies. This approach therefore offers promises for development of immunotherapeutic regimen for shrimp tropomyosin allergy.
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Christine Y Y
authors.initials: CY
authors.lastname: Wai
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Nicki Y H
authors.initials: NY
authors.lastname: Leung
authors.affiliation: Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Marco H K
authors.initials: MH
authors.lastname: Ho
authors.affiliation: Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America.
authors.forename: Laurel J
authors.initials: LJ
authors.lastname: Gershwin
authors.affiliation: Division of Rheumatology/Allergy, School of Medicine, University of California Davis, Davis, California, United States of America.
authors.forename: Shang An
authors.initials: SA
authors.lastname: Shu
authors.affiliation: Division of Rheumatology/Allergy, School of Medicine, University of California Davis, Davis, California, United States of America.
authors.forename: Patrick S C
authors.initials: PS
authors.lastname: Leung
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
authors.forename: Ka Hou
authors.initials: KH
authors.lastname: Chu
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology*; D004195:Disease Models, Animal; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000276:immunology; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D033561:Penaeidae / Q000276:immunology; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D016415:Sequence Alignment; D014335:Tropomyosin / Q000235:genetics / Q000276:immunology*
chemical_list: D000485:Allergens; D000939:Epitopes; D007074:Immunoglobulin G; C102464:Met e 1 allergen; D011506:Proteins; D011994:Recombinant Proteins; D014335:Tropomyosin; D007073:Immunoglobulin E