Protein changes in Trichinella spiralis muscle larvae in vitro induced by bovine bile

The purpose of this study was to investigate bovine bile induced protein changes within Trichinella spiralis muscle larvae (ML) in vitro. The larvae were activated by 5% raw bovine bile diluted in saline and in serum-free RPMI-1640 medium at 37°C in 5% CO2 for 2h and, respectively. The crude and excretory-secretory (ES) antigens from ML were analyzed by SDS-PAGE and Western blot. Following activation and comparison to blots of non-activated ML, blots of activated T. spiralis crude worm extract gave rise to three new protein bands (133, 125, and 26 kDa) when screened with mouse infection sera, and four new bands (125, 116, 80, and 29 kDa) when screened with sera from mice immunized with ES antigen. In the same screenings, a loss of two bands migrating at 106 and 25 kDa, and three bands migrating at 76, 58, and 16 kDa, respectively, was observed. When ES antigens from activated ML were blotted and compared to non-activated ML, four new bands (136, 39, 38, and 36 kDa) and seven new bands (136, 120, 100, 39, 36, 34, and 31 kDa) appeared when screened with infection sera and ES immune sera, respectively. In the same comparison, two bands migrating at 67 and 20 kDa, and ten bands migrating at 132, 112, 33, 32, 26, 23, 21, 19, 16, and 15 kDa, were no longer recognized by the ML infection sera and immune sera, respectively. The results showed that after the ML were activated by bile, their protein profiles changed. It is not yet clear if this change is related to the induction or loss of synthesized proteins, or to changes in the migration profiles of existing proteins as a result of post-translational modifications.