Molecular cloning and characterization of a 21 kDa protein secreted from Trichinella pseudospiralis

Recombinant protein was produced from the cDNA library of Trichinella pseud ospiralis, which seemed to form part of the excretory-secretory (ES) produc ts. The library was constructed from cDNA of muscle larvae at 1 month post- infection, and immunoscreened with antibody against T pseudospiralis ES pro ducts. A clone, designated Tp21-3, contained a cDNA transcript of 657 by in length with a single open reading frame, which encoded 172 amino acids (19 617 Da in the estimated molecular mass). The predicted amino acid sequence of clone Tp21-3 had a similarity of 76% to that of clone ORF 17.20 (GenBank under accession number U88239) from T. spiralis. The recombinant fusion pr oteins encoded by clone Tp21-3 were produced in an Escherichia coli express ion system and affinity purified. On Western blotting analysis, Tp21-3 reco mbinant proteins migrated at 40 kDa and reacted to antibody against T. pseu dospiralis ES products and T. pseudospiralis-infected sera. Sera were devel oped against Tp 21-3 recombinant proteins, which reacted to a single band m igrating at 21 kDa in crude worm extract and ES products from T. pseudospir alis on Western blotting analysis, and reacted with stichocytes of T. pseud ospiralis on immunohistochemical staining.