Proteomic analysis of Trichinella spiralis proteins in intestinal epithelial cells after culture with their larvae by shotgun LC-MS/MS approach.

Although it has been known for many years that Trichinella spiralis initiates infection by invading intestinal epithelium, the mechanisms by which the parasite invades the intestinal epithelium are unknown. The purpose of this study was to screen the invasion-related proteins among the increased proteins of intestinal epithelial cells after culture with T. spiralis and to study their molecular functions. The proteins of HCT-8 cells which cultured with T. spiralis infective larvae were analyzed by SDS-PAGE and Western blot. Results showed that compared with proteins of normal HCT-8 cells, four additional protein bands (115, 61, 35 and 24 kDa) of HCT-8 cells cultured with the infective larvae were recognized by sera of the mice infected with T. spiralis, which may be the invasion-related proteins released by the infective larvae. Three bands (61, 35 and 24 kDa) were studied employing shotgun LC-MS/MS. Total 64 proteins of T. spiralis were identified from T. spiralis protein database by using SEQUEST searches, of which 43 (67.2%) proteins were distributed in a range of 10-70 kDa, and 26 proteins (40.6%) were in the range of pI 5-6. Fifty-four proteins were annotated according to Gene Ontology Annotation in terms of molecular function, biological process, and cellular localization. Out of 54 annotated proteins, 43 proteins (79.6%) had binding activity and 23 proteins (42.6%) had catalytic activity (e.g. hydrolase, transferase, etc.), which might be related to the invasion of intestinal epithelial cells by T. spiralis. The protein profile provides a valuable basis for further studies of the invasion-related proteins of T. spiralis.