COMPARISON OF ALLERGENIC PROTEINS OF SEA SNAIL (CERITHIDEA OBTUSA) AND FRESHWATER SNAIL (POMACEA CANALICULATA)

In Malaysian and certain Asian countries, snail has high market demand and popular to the local people as food. However, snail is also frequently reported as one of the worst food allergens, dominated by severe symptoms such as asthma and anaphylactic shock. Thus, the aims of this study is to determine the allergenicity of two species of edible snails; the local sea snail, Cerithidea obtusa and the freshwater snail Pomacea canaliculata. Snail extracts were prepared from the snail flesh and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to determine their protein profiling. Allergenic proteins were detected by immunoblotting test using sera from 10 snail-allergic patients. The snails contain 31 to 34 protein fractions between 11 to >250 kDa. The prominent bands were seen at 33, 42, 74 and 250 kDa. Immunoblotting detected 15 and 16 allergenic proteins in C. obtusa and P. canaliculata, respectively. Three protein fractions at 30, 33 and 42 kDa were identified as the major allergens of C. obtusa, while six major allergens at 30, 33, 42, 74, 124 and 218 kDa were detected in P. canaliculata. Various minor allergens were also detected in both snails. This study indicated that numerous proteins of C. obtusa and P. canaliculata were allergenic. Thus, combined allergen extracts of both snails are essential to be included in diagnosis of snail allergy among local allergic patients.