Monoclonal antibody-based sandwich ELISA for reliable identification of imported Pangasius catfish.

Pangasius catfish, primarily tra (Pangasius hypophthalmus) and basa (Pangasius bocourti), are farm-raised catfish imported from Asia and have become a common substitute for domestic catfish, grouper, and other high-valued fish in restaurant-served dishes in the United States. This article reports on the development of a monoclonal antibody-based sandwich enzyme-linked immunosorbent assay (ELISA) for the identification of cooked Pangasius fish, basa, and tra. The assay uses a pair of monoclonal antibodies (MAbs F7B8 and T7E10) specific to a heat-stable 36-kDa protein present in a saline extraction of the fish muscle; MAb F7B8, which cross-reacts to all fish species, is the capture antibody and the biotin-conjugated MAb T7E10, which is specific to Pangasius fish, is the detection antibody. This sandwich ELISA reliably identified fully cooked basa and tra from more than 70 common finfish, shellfish, land animal species, and other protein materials tested. It can also sensitively detect 0.5% of adulterated basa or 0.1% tra in a mixed crabmeat products with low intra-assay (%CV: 2.59 to 4.14) and inter-assay (%CV: 3.36 to 3.71) variabilities. The new assay provides a rapid and reliable means of distinguishing fish in the Pangasiidae family from other common food fish and nonfish species and will greatly assist efforts to discourage the illegal practice of substituting high-value popular fish species by the cheaper farm-raised imported Pangasius fish at the retail and restaurant levels.