Cloning, isolation, and IgE-binding properties of Helix aspersa (brown garden snail) tropomyosin.
BACKGROUND
Gastropod consumption is quite frequent in the Mediterranean countries and cross-reactivities with crustaceans have been described, but the mechanism of this allergenic cross-reactivity has not been studied in detail. This study aimed to produce recombinant Helix aspersa (brown garden snail) tropomyosin and investigate its implication for cross-reactivity among invertebrates.


METHODS
A tropomyosin-specific cDNA encoding H. aspersa tropomyosin was synthetized, and recombinant allergen was overexpressed in Escherichia coli as nonfusion protein. IgE-binding reactivity was studied by immunoblotting and immunoblot inhibition experiments with sera from snail-allergic patients.


RESULTS
Cloned brown garden snail tropomyosin shares high homology with other edible mollusk tropomyosins (84-69% identity) as well as with those from arthropods (65-62%), and less homology with vertebrate ones (56% identity). Tropomyosin reacted with 18% of the sera from patients with snail allergy. Inhibition experiments, using natural and recombinant tropomyosins, showed different degrees of cross-reactivity between invertebrate tropomyosins. Sera from snail-allergic subjects recognized tropomyosins in both mollusks and crustacean extracts.


CONCLUSIONS
Tropomyosin represents a minor allergen in snail extracts, but it is clearly involved in invertebrate cross-reactivity.
Asturias
Juan A
JA
Bial-Arístegui, Research and Development Department, Bilbao, Spain. la.lp@bial.es
Eraso
Elena
E
Arilla
M Carmen
MC
Gómez-Bayón
Nuria
N
Inácio
Filipe
F
Martínez
Alberto
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D003429:Cross Reactions; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005512:Food Hypersensitivity / Q000097:blood / Q000276:immunology*; D006372:Helix, Snails / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology* / Q000378:metabolism; D008969:Molecular Sequence Data; D008974:Mollusca; D009132:Muscles / Q000737:chemistry / Q000276:immunology; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014020:Tissue Extracts / Q000276:immunology; D014335:Tropomyosin / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification
D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014020:Tissue Extracts; D014335:Tropomyosin; D007073:Immunoglobulin E