Protein change of intestinal epithelial cells induced in vitro by Trichinella spiralis infective larvae

The aim of this study was to observe the protein changes of intestinal epithelial cells induced in vitro by Trichinella spiralis infective larvae and their excretory-secretory (ES) or surface antigens and identity the proteins related with invasion. HCT-8 cells were incubated for 2 h in the culture medium contained ES or surface antigens of infective larvae, and observed by Immunofluorescent test (IFT). The infective larvae were inoculated into culture of HCT-8 cells to incubate for 18 h, and the lysates of HCT-8 cells were analyzed by SDS-PAGE and Western blot. IFA showed that normal HCT-8 cells had positively reactions with sera of the infected mice and mice immunized with ES or surface antigens. However, after incubating with ES or surface antigens, HCT-8 cells had stronger positively reaction with the above sera. On Western blot, after cultured with infective larvae, additional seven protein bands (66, 61, 57, 45, 34, 21, and 17 kDa) of HCT-8 cells were recognized by sera of the infected or immunized mice, but three protein bands (48, 43, and 23 kDa) of HCT-8 cells were not recognized by the above sera, compared with normal HCT-8 cells. Our results showed that after cultured with infective larvae the protein components of HCT-8 cell changed, suggesting that additional seven proteins recognized by sera of the infected or immunized mice may be related with invasion of intestinal epithelial cells by infective larvae, these proteins might mediate or facilitate entry into the cells, while the three proteins not recognized by the above sera may be the specific mediators released from the cells which permit invasion.