Characterization of a Trichinella spiralis 31 kDa protein and its potential application for the serodiagnosis of trichinellosis

The Trichinella spiralis 31 kDa protein (Ts31) was screened from the excretory-secretory (ES) proteins of muscle larvae (ML) by immunoproteomics using serum from mice infected with T. spiralis at 18 days post infection (dpi). The aim of this study was to characterize the Ts31 protein and to evaluate the potential of the recombinant Ts31 protein (rTs31) for serodiagnosis of human trichinellosis. Ts31 gene was cloned and rTs31 was produced in an E. coli expression system. An anti-rTs31serum recognized the native protein migrating in a 25–55 kDa range by Western blotting of ML crude or ES antigens. Expression of Ts31 gene was observed at all developmental stages of T. spiralis (adult worms, newborn larvae, pre-encapsulated larvae and ML). An immunolocalization analysis identified Ts31 in the cuticle and stichocytes of the parasite. The sensitivity of rTs31-ELISA and ES antigen ELISA for detecting anti-Trichinella IgG antibodies in sera of patients with trichinellosis was 97.83% (45/46) and 86.78% (39/46), respectively (P > 0.05); The specificity of rTs31-ELISA was 99.13% (114/115), which was significantly higher than 85.22% (98/115) of ES antigen ELISA (P < 0.01). The rTs31 protein of T. spiralis could be considered as a potential diagnostic antigen for trichinellosis.