Objective:To characterize the major allergens of Macrobrachium rosenbergii.(giant freshwater prawn).Methods:Raw and cooked extracts of the giant freshwater prawn were prepared.The IgE reactivity pattern was identified by sodium dodecyl sulfate polyaerylamide gel electrophoresis(SDS-PAGE)and immunoblotting technique with the sera of 20 skin prick test(SPT)positive patients.The major allergen identified was then characterized using the proteomics approach involving a combination of two-dimensional(2-DE)electrophoresis,mass spectrometry and bioinformatics tools.Results:SDS-PAGE of the raw extract showed 23 protein bands(15-250 kDa)but those ranging from 40 to 100 kDa were not found in the cooked extract.From immunoblotting experiments,raw and cooked extracts demonstrated 11 and 5 IgE-binding proteins,respectively,with a molecular mass ranging from 15 to 155 kDa.A heat-resistant 36 kDa protein was identified as the major allergen of both extracts.In addition,a 42 kDa heat-sensitive protein was shown to be a major allergen of the raw extract.The 2-DE gel fractionated the prawn proteins to more than 50 different protein spots.Of these,10 spots showed specific:IgE reactivity with patients’sera.Matrix assisted laser desorption/ionization-lime of flight(MALDI-TOF)analysis led to identification of 2 important allergens,tropomyosin and arginine kinase.Conclusions:It can be concluded that the availability of such allergens would help in component-based diagnosis and therapy of prawn allergies.